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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>Changes of the V4L2 API</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API" /><link rel="up" href="ch07.html" title="Chapter 7. Changes" /><link rel="prev" href="ch07.html" title="Chapter 7. Changes" /><link rel="next" href="ch07s03.html" title="Relation of V4L2 to other Linux multimedia APIs" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Changes of the V4L2 API</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch07.html">Prev</a> </td><th width="60%" align="center">Chapter 7. Changes</th><td width="20%" align="right"> <a accesskey="n" href="ch07s03.html">Next</a></td></tr></table><hr /></div><div class="section" title="Changes of the V4L2 API"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="hist-v4l2"></a>Changes of the V4L2 API</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="ch07s02.html#id2670451">Early Versions</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2670665">V4L2 Version 0.16 1999-01-31</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2670680">V4L2 Version 0.18 1999-03-16</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2670696">V4L2 Version 0.19 1999-06-05</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2670741">V4L2 Version 0.20 (1999-09-10)</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2671044">V4L2 Version 0.20 incremental changes</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2671293">V4L2 Version 0.20 2000-11-23</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2671440">V4L2 Version 0.20 2002-07-25</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2671451">V4L2 in Linux 2.5.46, 2002-10</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673058">V4L2 2003-06-19</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673241">V4L2 2003-11-05</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673398">V4L2 in Linux 2.6.6, 2004-05-09</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673433">V4L2 in Linux 2.6.8</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673480">V4L2 spec erratum 2004-08-01</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673559">V4L2 in Linux 2.6.14</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673599">V4L2 in Linux 2.6.15</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673710">V4L2 spec erratum 2005-11-27</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673750">V4L2 spec erratum 2006-01-10</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673800">V4L2 spec erratum 2006-02-03</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673842">V4L2 spec erratum 2006-02-04</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673890">V4L2 in Linux 2.6.17</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2673969">V4L2 spec erratum 2006-09-23 (Draft 0.15)</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674140">V4L2 in Linux 2.6.18</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674234">V4L2 in Linux 2.6.19</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674320">V4L2 spec erratum 2006-10-12 (Draft 0.17)</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674351">V4L2 in Linux 2.6.21</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674381">V4L2 in Linux 2.6.22</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674505">V4L2 in Linux 2.6.24</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674545">V4L2 in Linux 2.6.25</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674723">V4L2 in Linux 2.6.26</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674767">V4L2 in Linux 2.6.27</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674836">V4L2 in Linux 2.6.28</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674894">V4L2 in Linux 2.6.29</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2674986">V4L2 in Linux 2.6.30</a></span></dt><dt><span class="section"><a href="ch07s02.html#id2675021">V4L2 in Linux 2.6.32</a></span></dt></dl></div><p>Soon after the V4L API was added to the kernel it was
criticised as too inflexible. In August 1998 Bill Dirks proposed a
number of improvements and began to work on documentation, example
drivers and applications. With the help of other volunteers this
eventually became the V4L2 API, not just an extension but a
replacement for the V4L API. However it took another four years and
two stable kernel releases until the new API was finally accepted for
inclusion into the kernel in its present form.</p><div class="section" title="Early Versions"><div class="titlepage"><div><div><h3 class="title"><a id="id2670451"></a>Early Versions</h3></div></div></div><p>1998-08-20: First version.</p><p>1998-08-27: The <a class="link" href="re67.html" title="V4L2 select()"><code class="function">select()</code></a> function was introduced.</p><p>1998-09-10: New video standard interface.</p><p>1998-09-18: The <code class="constant">VIDIOC_NONCAP</code> ioctl
was replaced by the otherwise meaningless <code class="constant">O_TRUNC</code>
<a class="link" href="re64.html" title="V4L2 open()"><code class="function">open()</code></a> flag, and the aliases <code class="constant">O_NONCAP</code> and
<code class="constant">O_NOIO</code> were defined. Applications can set this
flag if they intend to access controls only, as opposed to capture
applications which need exclusive access. The
<code class="constant">VIDEO_STD_XXX</code> identifiers are now ordinals
instead of flags, and the <code class="function">video_std_construct()</code>
helper function takes id and transmission arguments.</p><p>1998-09-28: Revamped video standard. Made video controls
individually enumerable.</p><p>1998-10-02: The <em class="structfield"><code>id</code></em> field was
removed from struct <span class="structname">video_standard</span> and the
color subcarrier fields were renamed. The <a class="link" href="re58.html" title="ioctl VIDIOC_QUERYSTD"><code class="constant">VIDIOC_QUERYSTD</code></a> ioctl was
renamed to <a class="link" href="re33.html" title="ioctl VIDIOC_ENUMSTD"><code class="constant">VIDIOC_ENUMSTD</code></a>, <a class="link" href="re43.html" title="ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT"><code class="constant">VIDIOC_G_INPUT</code></a> to <a class="link" href="re31.html" title="ioctl VIDIOC_ENUMINPUT"><code class="constant">VIDIOC_ENUMINPUT</code></a>. A
first draft of the Codec API was released.</p><p>1998-11-08: Many minor changes. Most symbols have been
renamed. Some material changes to struct <a class="link" href="re56.html#v4l2-capability" title="Table A.66. struct v4l2_capability">v4l2_capability</a>.</p><p>1998-11-12: The read/write directon of some ioctls was misdefined.</p><p>1998-11-14: <code class="constant">V4L2_PIX_FMT_RGB24</code>
changed to <code class="constant">V4L2_PIX_FMT_BGR24</code>, and
<code class="constant">V4L2_PIX_FMT_RGB32</code> changed to
<code class="constant">V4L2_PIX_FMT_BGR32</code>. Audio controls are now
accessible with the <a class="link" href="re37.html" title="ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL"><code class="constant">VIDIOC_G_CTRL</code></a> and <a class="link" href="re37.html" title="ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL"><code class="constant">VIDIOC_S_CTRL</code></a> ioctls under
names starting with <code class="constant">V4L2_CID_AUDIO</code>. The
<code class="constant">V4L2_MAJOR</code> define was removed from
<code class="filename">videodev.h</code> since it was only used once in the
<code class="filename">videodev</code> kernel module. The
<code class="constant">YUV422</code> and <code class="constant">YUV411</code> planar
image formats were added.</p><p>1998-11-28: A few ioctl symbols changed. Interfaces for codecs and
video output devices were added.</p><p>1999-01-14: A raw VBI capture interface was added.</p><p>1999-01-19: The <code class="constant">VIDIOC_NEXTBUF</code> ioctl
was removed.</p></div><div class="section" title="V4L2 Version 0.16 1999-01-31"><div class="titlepage"><div><div><h3 class="title"><a id="id2670665"></a>V4L2 Version 0.16 1999-01-31</h3></div></div></div><p>1999-01-27: There is now one QBUF ioctl, VIDIOC_QWBUF and VIDIOC_QRBUF
are gone. VIDIOC_QBUF takes a v4l2_buffer as a parameter. Added
digital zoom (cropping) controls.</p></div><div class="section" title="V4L2 Version 0.18 1999-03-16"><div class="titlepage"><div><div><h3 class="title"><a id="id2670680"></a>V4L2 Version 0.18 1999-03-16</h3></div></div></div><p>Added a v4l to V4L2 ioctl compatibility layer to
videodev.c. Driver writers, this changes how you implement your ioctl
handler. See the Driver Writer's Guide. Added some more control id
codes.</p></div><div class="section" title="V4L2 Version 0.19 1999-06-05"><div class="titlepage"><div><div><h3 class="title"><a id="id2670696"></a>V4L2 Version 0.19 1999-06-05</h3></div></div></div><p>1999-03-18: Fill in the category and catname fields of
v4l2_queryctrl objects before passing them to the driver. Required a
minor change to the VIDIOC_QUERYCTRL handlers in the sample
drivers.</p><p>1999-03-31: Better compatibility for v4l memory capture
ioctls. Requires changes to drivers to fully support new compatibility
features, see Driver Writer's Guide and v4l2cap.c. Added new control
IDs: V4L2_CID_HFLIP, _VFLIP. Changed V4L2_PIX_FMT_YUV422P to _YUV422P,
and _YUV411P to _YUV411P.</p><p>1999-04-04: Added a few more control IDs.</p><p>1999-04-07: Added the button control type.</p><p>1999-05-02: Fixed a typo in videodev.h, and added the
V4L2_CTRL_FLAG_GRAYED (later V4L2_CTRL_FLAG_GRABBED) flag.</p><p>1999-05-20: Definition of VIDIOC_G_CTRL was wrong causing
a malfunction of this ioctl.</p><p>1999-06-05: Changed the value of
V4L2_CID_WHITENESS.</p></div><div class="section" title="V4L2 Version 0.20 (1999-09-10)"><div class="titlepage"><div><div><h3 class="title"><a id="id2670741"></a>V4L2 Version 0.20 (1999-09-10)</h3></div></div></div><p>Version 0.20 introduced a number of changes which were
<span class="emphasis"><em>not backward compatible</em></span> with 0.19 and earlier
versions. Purpose of these changes was to simplify the API, while
making it more extensible and following common Linux driver API
conventions.</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Some typos in <code class="constant">V4L2_FMT_FLAG</code>
symbols were fixed. struct <a class="link" href="ch04s02.html#v4l2-clip" title="Table 4.2. struct v4l2_clip">v4l2_clip</a> was changed for compatibility with
v4l. (1999-08-30)</p></li><li class="listitem"><p><code class="constant">V4L2_TUNER_SUB_LANG1</code> was added.
(1999-09-05)</p></li><li class="listitem"><p>All ioctl() commands that used an integer argument now
take a pointer to an integer. Where it makes sense, ioctls will return
the actual new value in the integer pointed to by the argument, a
common convention in the V4L2 API. The affected ioctls are:
VIDIOC_PREVIEW, VIDIOC_STREAMON, VIDIOC_STREAMOFF, VIDIOC_S_FREQ,
VIDIOC_S_INPUT, VIDIOC_S_OUTPUT, VIDIOC_S_EFFECT. For example
</p><pre class="programlisting">
err = ioctl (fd, VIDIOC_XXX, V4L2_XXX);
</pre><p> becomes </p><pre class="programlisting">
int a = V4L2_XXX; err = ioctl(fd, VIDIOC_XXX, &a);
</pre><p>
</p></li><li class="listitem"><p>All the different get- and set-format commands were
swept into one <a class="link" href="re41.html" title="ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT"><code class="constant">VIDIOC_G_FMT</code></a> and <a class="link" href="re41.html" title="ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT"><code class="constant">VIDIOC_S_FMT</code></a> ioctl taking a union
and a type field selecting the union member as parameter. Purpose is to
simplify the API by eliminating several ioctls and to allow new and
driver private data streams without adding new ioctls.</p><p>This change obsoletes the following ioctls:
<code class="constant">VIDIOC_S_INFMT</code>,
<code class="constant">VIDIOC_G_INFMT</code>,
<code class="constant">VIDIOC_S_OUTFMT</code>,
<code class="constant">VIDIOC_G_OUTFMT</code>,
<code class="constant">VIDIOC_S_VBIFMT</code> and
<code class="constant">VIDIOC_G_VBIFMT</code>. The image format structure
<span class="structname">v4l2_format</span> was renamed to struct <a class="link" href="ch02.html#v4l2-pix-format" title="Table 2.1. struct v4l2_pix_format">v4l2_pix_format</a>,
while struct <a class="link" href="re41.html#v4l2-format" title="Table A.46. struct v4l2_format">v4l2_format</a> is now the envelopping structure for all format
negotiations.</p></li><li class="listitem"><p>Similar to the changes above, the
<code class="constant">VIDIOC_G_PARM</code> and
<code class="constant">VIDIOC_S_PARM</code> ioctls were merged with
<code class="constant">VIDIOC_G_OUTPARM</code> and
<code class="constant">VIDIOC_S_OUTPARM</code>. A
<em class="structfield"><code>type</code></em> field in the new struct <a class="link" href="re47.html#v4l2-streamparm" title="Table A.52. struct v4l2_streamparm">v4l2_streamparm</a>
selects the respective union member.</p><p>This change obsoletes the
<code class="constant">VIDIOC_G_OUTPARM</code> and
<code class="constant">VIDIOC_S_OUTPARM</code> ioctls.</p></li><li class="listitem"><p>Control enumeration was simplified, and two new
control flags were introduced and one dropped. The
<em class="structfield"><code>catname</code></em> field was replaced by a
<em class="structfield"><code>group</code></em> field.</p><p>Drivers can now flag unsupported and temporarily
unavailable controls with <code class="constant">V4L2_CTRL_FLAG_DISABLED</code>
and <code class="constant">V4L2_CTRL_FLAG_GRABBED</code> respectively. The
<em class="structfield"><code>group</code></em> name indicates a possibly narrower
classification than the <em class="structfield"><code>category</code></em>. In other
words, there may be multiple groups within a category. Controls within
a group would typically be drawn within a group box. Controls in
different categories might have a greater separation, or may even
appear in separate windows.</p></li><li class="listitem"><p>The struct <a class="link" href="ch03s05.html#v4l2-buffer" title="Table 3.1. struct v4l2_buffer">v4l2_buffer</a> <em class="structfield"><code>timestamp</code></em>
was changed to a 64 bit integer, containing the sampling or output
time of the frame in nanoseconds. Additionally timestamps will be in
absolute system time, not starting from zero at the beginning of a
stream. The data type name for timestamps is stamp_t, defined as a
signed 64-bit integer. Output devices should not send a buffer out
until the time in the timestamp field has arrived. I would like to
follow SGI's lead, and adopt a multimedia timestamping system like
their UST (Unadjusted System Time). See
http://reality.sgi.com/cpirazzi_engr/lg/time/intro.html. [This link is
no longer valid.] UST uses timestamps that are 64-bit signed integers
(not struct timeval's) and given in nanosecond units. The UST clock
starts at zero when the system is booted and runs continuously and
uniformly. It takes a little over 292 years for UST to overflow. There
is no way to set the UST clock. The regular Linux time-of-day clock
can be changed periodically, which would cause errors if it were being
used for timestamping a multimedia stream. A real UST style clock will
require some support in the kernel that is not there yet. But in
anticipation, I will change the timestamp field to a 64-bit integer,
and I will change the v4l2_masterclock_gettime() function (used only
by drivers) to return a 64-bit integer.</p></li><li class="listitem"><p>A <em class="structfield"><code>sequence</code></em> field was added
to struct <a class="link" href="ch03s05.html#v4l2-buffer" title="Table 3.1. struct v4l2_buffer">v4l2_buffer</a>. The <em class="structfield"><code>sequence</code></em> field counts
captured frames, it is ignored by output devices. When a capture
driver drops a frame, the sequence number of that frame is
skipped.</p></li></ol></div></div><div class="section" title="V4L2 Version 0.20 incremental changes"><div class="titlepage"><div><div><h3 class="title"><a id="id2671044"></a>V4L2 Version 0.20 incremental changes</h3></div></div></div><p>1999-12-23: In struct <a class="link" href="ch04s07.html#v4l2-vbi-format" title="Table 4.4. struct v4l2_vbi_format">v4l2_vbi_format</a> the
<em class="structfield"><code>reserved1</code></em> field became
<em class="structfield"><code>offset</code></em>. Previously drivers were required to
clear the <em class="structfield"><code>reserved1</code></em> field.</p><p>2000-01-13: The
<code class="constant">V4L2_FMT_FLAG_NOT_INTERLACED</code> flag was added.</p><p>2000-07-31: The <code class="filename">linux/poll.h</code> header
is now included by <code class="filename">videodev.h</code> for compatibility
with the original <code class="filename">videodev.h</code> file.</p><p>2000-11-20: <code class="constant">V4L2_TYPE_VBI_OUTPUT</code> and
<code class="constant">V4L2_PIX_FMT_Y41P</code> were added.</p><p>2000-11-25: <code class="constant">V4L2_TYPE_VBI_INPUT</code> was
added.</p><p>2000-12-04: A couple typos in symbol names were fixed.</p><p>2001-01-18: To avoid namespace conflicts the
<code class="constant">fourcc</code> macro defined in the
<code class="filename">videodev.h</code> header file was renamed to
<code class="constant">v4l2_fourcc</code>.</p><p>2001-01-25: A possible driver-level compatibility problem
between the <code class="filename">videodev.h</code> file in Linux 2.4.0 and
the <code class="filename">videodev.h</code> file included in the
<code class="filename">videodevX</code> patch was fixed. Users of an earlier
version of <code class="filename">videodevX</code> on Linux 2.4.0 should
recompile their V4L and V4L2 drivers.</p><p>2001-01-26: A possible kernel-level incompatibility
between the <code class="filename">videodev.h</code> file in the
<code class="filename">videodevX</code> patch and the
<code class="filename">videodev.h</code> file in Linux 2.2.x with devfs patches
applied was fixed.</p><p>2001-03-02: Certain V4L ioctls which pass data in both
direction although they are defined with read-only parameter, did not
work correctly through the backward compatibility layer.
[Solution?]</p><p>2001-04-13: Big endian 16-bit RGB formats were added.</p><p>2001-09-17: New YUV formats and the <a class="link" href="re42.html" title="ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY"><code class="constant">VIDIOC_G_FREQUENCY</code></a> and
<a class="link" href="re42.html" title="ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY"><code class="constant">VIDIOC_S_FREQUENCY</code></a> ioctls were added. (The old
<code class="constant">VIDIOC_G_FREQ</code> and
<code class="constant">VIDIOC_S_FREQ</code> ioctls did not take multiple tuners
into account.)</p><p>2000-09-18: <code class="constant">V4L2_BUF_TYPE_VBI</code> was
added. This may <span class="emphasis"><em>break compatibility</em></span> as the
<a class="link" href="re41.html" title="ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT"><code class="constant">VIDIOC_G_FMT</code></a> and <a class="link" href="re41.html" title="ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT"><code class="constant">VIDIOC_S_FMT</code></a> ioctls may fail now if the struct
<span class="structname">v4l2_fmt</span> <em class="structfield"><code>type</code></em>
field does not contain <code class="constant">V4L2_BUF_TYPE_VBI</code>. In the
documentation of the struct <a class="link" href="ch04s07.html#v4l2-vbi-format" title="Table 4.4. struct v4l2_vbi_format">v4l2_vbi_format</a>
<em class="structfield"><code>offset</code></em> field the ambiguous phrase "rising
edge" was changed to "leading edge".</p></div><div class="section" title="V4L2 Version 0.20 2000-11-23"><div class="titlepage"><div><div><h3 class="title"><a id="id2671293"></a>V4L2 Version 0.20 2000-11-23</h3></div></div></div><p>A number of changes were made to the raw VBI
interface.</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Figures clarifying the line numbering scheme were
added to the V4L2 API specification. The
<em class="structfield"><code>start</code></em>[0] and
<em class="structfield"><code>start</code></em>[1] fields no longer count line
numbers beginning at zero. Rationale: a) The previous definition was
unclear. b) The <em class="structfield"><code>start</code></em>[] values are ordinal
numbers. c) There is no point in inventing a new line numbering
scheme. We now use line number as defined by ITU-R, period.
Compatibility: Add one to the start values. Applications depending on
the previous semantics may not function correctly.</p></li><li class="listitem"><p>The restriction "count[0] > 0 and count[1] > 0"
has been relaxed to "(count[0] + count[1]) > 0". Rationale:
Drivers may allocate resources at scan line granularity and some data
services are transmitted only on the first field. The comment that
both <em class="structfield"><code>count</code></em> values will usually be equal is
misleading and pointless and has been removed. This change
<span class="emphasis"><em>breaks compatibility</em></span> with earlier versions:
Drivers may return EINVAL, applications may not function
correctly.</p></li><li class="listitem"><p>Drivers are again permitted to return negative
(unknown) start values as proposed earlier. Why this feature was
dropped is unclear. This change may <span class="emphasis"><em>break
compatibility</em></span> with applications depending on the start
values being positive. The use of <code class="constant">EBUSY</code> and
<code class="constant">EINVAL</code> error codes with the <a class="link" href="re41.html" title="ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT"><code class="constant">VIDIOC_S_FMT</code></a> ioctl
was clarified. The <span class="errorcode">EBUSY</span> error code was finally documented, and the
<em class="structfield"><code>reserved2</code></em> field which was previously
mentioned only in the <code class="filename">videodev.h</code> header
file.</p></li><li class="listitem"><p>New buffer types
<code class="constant">V4L2_TYPE_VBI_INPUT</code> and
<code class="constant">V4L2_TYPE_VBI_OUTPUT</code> were added. The former is an
alias for the old <code class="constant">V4L2_TYPE_VBI</code>, the latter was
missing in the <code class="filename">videodev.h</code> file.</p></li></ol></div></div><div class="section" title="V4L2 Version 0.20 2002-07-25"><div class="titlepage"><div><div><h3 class="title"><a id="id2671440"></a>V4L2 Version 0.20 2002-07-25</h3></div></div></div><p>Added sliced VBI interface proposal.</p></div><div class="section" title="V4L2 in Linux 2.5.46, 2002-10"><div class="titlepage"><div><div><h3 class="title"><a id="id2671451"></a>V4L2 in Linux 2.5.46, 2002-10</h3></div></div></div><p>Around October-November 2002, prior to an announced
feature freeze of Linux 2.5, the API was revised, drawing from
experience with V4L2 0.20. This unnamed version was finally merged
into Linux 2.5.46.</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>As specified in <a class="xref" href="ch01.html#related" title="Related Devices">the section called “Related Devices”</a>, drivers
must make related device functions available under all minor device
numbers.</p></li><li class="listitem"><p>The <a class="link" href="re64.html" title="V4L2 open()"><code class="function">open()</code></a> function requires access mode
<code class="constant">O_RDWR</code> regardless of the device type. All V4L2
drivers exchanging data with applications must support the
<code class="constant">O_NONBLOCK</code> flag. The <code class="constant">O_NOIO</code>
flag, a V4L2 symbol which aliased the meaningless
<code class="constant">O_TRUNC</code> to indicate accesses without data
exchange (panel applications) was dropped. Drivers must stay in "panel
mode" until the application attempts to initiate a data exchange, see
<a class="xref" href="ch01.html#open" title="Opening and Closing Devices">the section called “Opening and Closing Devices”</a>.</p></li><li class="listitem"><p>The struct <a class="link" href="re56.html#v4l2-capability" title="Table A.66. struct v4l2_capability">v4l2_capability</a> changed dramatically. Note that
also the size of the structure changed, which is encoded in the ioctl
request code, thus older V4L2 devices will respond with an <span class="errorcode">EINVAL</span> error code to
the new <a class="link" href="re56.html" title="ioctl VIDIOC_QUERYCAP"><code class="constant">VIDIOC_QUERYCAP</code></a> ioctl.</p><p>There are new fields to identify the driver, a new RDS
device function <code class="constant">V4L2_CAP_RDS_CAPTURE</code>, the
<code class="constant">V4L2_CAP_AUDIO</code> flag indicates if the device has
any audio connectors, another I/O capability
<code class="constant">V4L2_CAP_ASYNCIO</code> can be flagged. In response to
these changes the <em class="structfield"><code>type</code></em> field became a bit
set and was merged into the <em class="structfield"><code>flags</code></em> field.
<code class="constant">V4L2_FLAG_TUNER</code> was renamed to
<code class="constant">V4L2_CAP_TUNER</code>,
<code class="constant">V4L2_CAP_VIDEO_OVERLAY</code> replaced
<code class="constant">V4L2_FLAG_PREVIEW</code> and
<code class="constant">V4L2_CAP_VBI_CAPTURE</code> and
<code class="constant">V4L2_CAP_VBI_OUTPUT</code> replaced
<code class="constant">V4L2_FLAG_DATA_SERVICE</code>.
<code class="constant">V4L2_FLAG_READ</code> and
<code class="constant">V4L2_FLAG_WRITE</code> were merged into
<code class="constant">V4L2_CAP_READWRITE</code>.</p><p>The redundant fields
<em class="structfield"><code>inputs</code></em>, <em class="structfield"><code>outputs</code></em>
and <em class="structfield"><code>audios</code></em> were removed. These properties
can be determined as described in <a class="xref" href="ch01s04.html" title="Video Inputs and Outputs">the section called “Video Inputs and Outputs”</a> and <a class="xref" href="ch01s05.html" title="Audio Inputs and Outputs">the section called “Audio Inputs and Outputs”</a>.</p><p>The somewhat volatile and therefore barely useful
fields <em class="structfield"><code>maxwidth</code></em>,
<em class="structfield"><code>maxheight</code></em>,
<em class="structfield"><code>minwidth</code></em>,
<em class="structfield"><code>minheight</code></em>,
<em class="structfield"><code>maxframerate</code></em> were removed. This information
is available as described in <a class="xref" href="ch01s10.html" title="Data Formats">the section called “Data Formats”</a> and
<a class="xref" href="ch01s07.html" title="Video Standards">the section called “Video Standards”</a>.</p><p><code class="constant">V4L2_FLAG_SELECT</code> was removed. We
believe the select() function is important enough to require support
of it in all V4L2 drivers exchanging data with applications. The
redundant <code class="constant">V4L2_FLAG_MONOCHROME</code> flag was removed,
this information is available as described in <a class="xref" href="ch01s10.html" title="Data Formats">the section called “Data Formats”</a>.</p></li><li class="listitem"><p>In struct <a class="link" href="re31.html#v4l2-input" title="Table A.22. struct v4l2_input">v4l2_input</a> the
<em class="structfield"><code>assoc_audio</code></em> field and the
<em class="structfield"><code>capability</code></em> field and its only flag
<code class="constant">V4L2_INPUT_CAP_AUDIO</code> was replaced by the new
<em class="structfield"><code>audioset</code></em> field. Instead of linking one
video input to one audio input this field reports all audio inputs
this video input combines with.</p><p>New fields are <em class="structfield"><code>tuner</code></em>
(reversing the former link from tuners to video inputs),
<em class="structfield"><code>std</code></em> and
<em class="structfield"><code>status</code></em>.</p><p>Accordingly struct <a class="link" href="re32.html#v4l2-output" title="Table A.25. struct v4l2_output">v4l2_output</a> lost its
<em class="structfield"><code>capability</code></em> and
<em class="structfield"><code>assoc_audio</code></em> fields.
<em class="structfield"><code>audioset</code></em>,
<em class="structfield"><code>modulator</code></em> and
<em class="structfield"><code>std</code></em> where added instead.</p></li><li class="listitem"><p>The struct <a class="link" href="re34.html#v4l2-audio" title="Table A.31. struct v4l2_audio">v4l2_audio</a> field
<em class="structfield"><code>audio</code></em> was renamed to
<em class="structfield"><code>index</code></em>, for consistency with other
structures. A new capability flag
<code class="constant">V4L2_AUDCAP_STEREO</code> was added to indicated if the
audio input in question supports stereo sound.
<code class="constant">V4L2_AUDCAP_EFFECTS</code> and the corresponding
<code class="constant">V4L2_AUDMODE</code> flags where removed. This can be
easily implemented using controls. (However the same applies to AVL
which is still there.)</p><p>Again for consistency the struct <a class="link" href="re35.html#v4l2-audioout" title="Table A.34. struct v4l2_audioout">v4l2_audioout</a> field
<em class="structfield"><code>audio</code></em> was renamed to
<em class="structfield"><code>index</code></em>.</p></li><li class="listitem"><p>The struct <a class="link" href="re51.html#v4l2-tuner" title="Table A.60. struct v4l2_tuner">v4l2_tuner</a>
<em class="structfield"><code>input</code></em> field was replaced by an
<em class="structfield"><code>index</code></em> field, permitting devices with
multiple tuners. The link between video inputs and tuners is now
reversed, inputs point to their tuner. The
<em class="structfield"><code>std</code></em> substructure became a
simple set (more about this below) and moved into struct <a class="link" href="re31.html#v4l2-input" title="Table A.22. struct v4l2_input">v4l2_input</a>. A
<em class="structfield"><code>type</code></em> field was added.</p><p>Accordingly in struct <a class="link" href="re45.html#v4l2-modulator" title="Table A.50. struct v4l2_modulator">v4l2_modulator</a> the
<em class="structfield"><code>output</code></em> was replaced by an
<em class="structfield"><code>index</code></em> field.</p><p>In struct <a class="link" href="re42.html#v4l2-frequency" title="Table A.47. struct v4l2_frequency">v4l2_frequency</a> the
<em class="structfield"><code>port</code></em> field was replaced by a
<em class="structfield"><code>tuner</code></em> field containing the respective tuner
or modulator index number. A tuner <em class="structfield"><code>type</code></em>
field was added and the <em class="structfield"><code>reserved</code></em> field
became larger for future extensions (satellite tuners in
particular).</p></li><li class="listitem"><p>The idea of completely transparent video standards was
dropped. Experience showed that applications must be able to work with
video standards beyond presenting the user a menu. Instead of
enumerating supported standards with an ioctl applications can now
refer to standards by <a class="link" href="re33.html#v4l2-std-id" title="Table A.29. typedef v4l2_std_id">v4l2_std_id</a> and symbols defined in the
<code class="filename">videodev2.h</code> header file. For details see <a class="xref" href="ch01s07.html" title="Video Standards">the section called “Video Standards”</a>. The <a class="link" href="re50.html" title="ioctl VIDIOC_G_STD, VIDIOC_S_STD"><code class="constant">VIDIOC_G_STD</code></a> and
<a class="link" href="re50.html" title="ioctl VIDIOC_G_STD, VIDIOC_S_STD"><code class="constant">VIDIOC_S_STD</code></a> now take a pointer to this type as argument.
<a class="link" href="re58.html" title="ioctl VIDIOC_QUERYSTD"><code class="constant">VIDIOC_QUERYSTD</code></a> was added to autodetect the received standard, if
the hardware has this capability. In struct <a class="link" href="re33.html#v4l2-standard" title="Table A.27. struct v4l2_standard">v4l2_standard</a> an
<em class="structfield"><code>index</code></em> field was added for <a class="link" href="re33.html" title="ioctl VIDIOC_ENUMSTD"><code class="constant">VIDIOC_ENUMSTD</code></a>.
A <a class="link" href="re33.html#v4l2-std-id" title="Table A.29. typedef v4l2_std_id">v4l2_std_id</a> field named <em class="structfield"><code>id</code></em> was added as
machine readable identifier, also replacing the
<em class="structfield"><code>transmission</code></em> field. The misleading
<em class="structfield"><code>framerate</code></em> field was renamed
to <em class="structfield"><code>frameperiod</code></em>. The now obsolete
<em class="structfield"><code>colorstandard</code></em> information, originally
needed to distguish between variations of standards, were
removed.</p><p>Struct <span class="structname">v4l2_enumstd</span> ceased to
be. <a class="link" href="re33.html" title="ioctl VIDIOC_ENUMSTD"><code class="constant">VIDIOC_ENUMSTD</code></a> now takes a pointer to a struct <a class="link" href="re33.html#v4l2-standard" title="Table A.27. struct v4l2_standard">v4l2_standard</a>
directly. The information which standards are supported by a
particular video input or output moved into struct <a class="link" href="re31.html#v4l2-input" title="Table A.22. struct v4l2_input">v4l2_input</a> and
struct <a class="link" href="re32.html#v4l2-output" title="Table A.25. struct v4l2_output">v4l2_output</a> fields named <em class="structfield"><code>std</code></em>,
respectively.</p></li><li class="listitem"><p>The struct <a class="link" href="re57.html#v4l2-queryctrl" title="Table A.68. struct v4l2_queryctrl">v4l2_queryctrl</a> fields
<em class="structfield"><code>category</code></em> and
<em class="structfield"><code>group</code></em> did not catch on and/or were not
implemented as expected and therefore removed.</p></li><li class="listitem"><p>The <a class="link" href="re41.html" title="ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT"><code class="constant">VIDIOC_TRY_FMT</code></a> ioctl was added to negotiate data
formats as with <a class="link" href="re41.html" title="ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT"><code class="constant">VIDIOC_S_FMT</code></a>, but without the overhead of
programming the hardware and regardless of I/O in progress.</p><p>In struct <a class="link" href="re41.html#v4l2-format" title="Table A.46. struct v4l2_format">v4l2_format</a> the <em class="structfield"><code>fmt</code></em>
union was extended to contain struct <a class="link" href="ch04s02.html#v4l2-window" title="Table 4.1. struct v4l2_window">v4l2_window</a>. All image format
negotiations are now possible with <code class="constant">VIDIOC_G_FMT</code>,
<code class="constant">VIDIOC_S_FMT</code> and
<code class="constant">VIDIOC_TRY_FMT</code>; ioctl. The
<code class="constant">VIDIOC_G_WIN</code> and
<code class="constant">VIDIOC_S_WIN</code> ioctls to prepare for a video
overlay were removed. The <em class="structfield"><code>type</code></em> field
changed to type enum <a class="link" href="ch03s05.html#v4l2-buf-type" title="Table 3.2. enum v4l2_buf_type">v4l2_buf_type</a> and the buffer type names changed as
follows.</p><div class="informaltable"><table border="1"><colgroup><col /><col /></colgroup><thead><tr><th>Old defines</th><th>enum <a class="link" href="ch03s05.html#v4l2-buf-type" title="Table 3.2. enum v4l2_buf_type">v4l2_buf_type</a></th></tr></thead><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_BUF_TYPE_CAPTURE</code></td><td valign="top"><code class="constant">V4L2_BUF_TYPE_VIDEO_CAPTURE</code></td></tr><tr><td valign="top"><code class="constant">V4L2_BUF_TYPE_CODECIN</code></td><td valign="top">Omitted for now</td></tr><tr><td valign="top"><code class="constant">V4L2_BUF_TYPE_CODECOUT</code></td><td valign="top">Omitted for now</td></tr><tr><td valign="top"><code class="constant">V4L2_BUF_TYPE_EFFECTSIN</code></td><td valign="top">Omitted for now</td></tr><tr><td valign="top"><code class="constant">V4L2_BUF_TYPE_EFFECTSIN2</code></td><td valign="top">Omitted for now</td></tr><tr><td valign="top"><code class="constant">V4L2_BUF_TYPE_EFFECTSOUT</code></td><td valign="top">Omitted for now</td></tr><tr><td valign="top"><code class="constant">V4L2_BUF_TYPE_VIDEOOUT</code></td><td valign="top"><code class="constant">V4L2_BUF_TYPE_VIDEO_OUTPUT</code></td></tr><tr><td valign="top"><code class="constant">-</code></td><td valign="top"><code class="constant">V4L2_BUF_TYPE_VIDEO_OVERLAY</code></td></tr><tr><td valign="top"><code class="constant">-</code></td><td valign="top"><code class="constant">V4L2_BUF_TYPE_VBI_CAPTURE</code></td></tr><tr><td valign="top"><code class="constant">-</code></td><td valign="top"><code class="constant">V4L2_BUF_TYPE_VBI_OUTPUT</code></td></tr><tr><td valign="top"><code class="constant">-</code></td><td valign="top"><code class="constant">V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</code></td></tr><tr><td valign="top"><code class="constant">-</code></td><td valign="top"><code class="constant">V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</code></td></tr><tr><td valign="top"><code class="constant">V4L2_BUF_TYPE_PRIVATE_BASE</code></td><td valign="top"><code class="constant">V4L2_BUF_TYPE_PRIVATE</code></td></tr></tbody></table></div></li><li class="listitem"><p>In struct <a class="link" href="re28.html#v4l2-fmtdesc" title="Table A.13. struct v4l2_fmtdesc">v4l2_fmtdesc</a> a enum <a class="link" href="ch03s05.html#v4l2-buf-type" title="Table 3.2. enum v4l2_buf_type">v4l2_buf_type</a> field named
<em class="structfield"><code>type</code></em> was added as in struct <a class="link" href="re41.html#v4l2-format" title="Table A.46. struct v4l2_format">v4l2_format</a>. The
<code class="constant">VIDIOC_ENUM_FBUFFMT</code> ioctl is no longer needed and
was removed. These calls can be replaced by <a class="link" href="re28.html" title="ioctl VIDIOC_ENUM_FMT"><code class="constant">VIDIOC_ENUM_FMT</code></a> with
type <code class="constant">V4L2_BUF_TYPE_VIDEO_OVERLAY</code>.</p></li><li class="listitem"><p>In struct <a class="link" href="ch02.html#v4l2-pix-format" title="Table 2.1. struct v4l2_pix_format">v4l2_pix_format</a> the
<em class="structfield"><code>depth</code></em> field was removed, assuming
applications which recognize the format by its four-character-code
already know the color depth, and others do not care about it. The
same rationale lead to the removal of the
<code class="constant">V4L2_FMT_FLAG_COMPRESSED</code> flag. The
<code class="constant">V4L2_FMT_FLAG_SWCONVECOMPRESSED</code> flag was removed
because drivers are not supposed to convert images in kernel space. A
user library of conversion functions should be provided instead. The
<code class="constant">V4L2_FMT_FLAG_BYTESPERLINE</code> flag was redundant.
Applications can set the <em class="structfield"><code>bytesperline</code></em> field
to zero to get a reasonable default. Since the remaining flags were
replaced as well, the <em class="structfield"><code>flags</code></em> field itself
was removed.</p><p>The interlace flags were replaced by a enum <a class="link" href="ch03s06.html#v4l2-field" title="Table 3.8. enum v4l2_field">v4l2_field</a>
value in a newly added <em class="structfield"><code>field</code></em>
field.</p><div class="informaltable"><table border="1"><colgroup><col /><col /></colgroup><thead><tr><th>Old flag</th><th>enum <a class="link" href="ch03s06.html#v4l2-field" title="Table 3.8. enum v4l2_field">v4l2_field</a></th></tr></thead><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_FMT_FLAG_NOT_INTERLACED</code></td><td valign="top">?</td></tr><tr><td valign="top"><code class="constant">V4L2_FMT_FLAG_INTERLACED</code>
= <code class="constant">V4L2_FMT_FLAG_COMBINED</code></td><td valign="top"><code class="constant">V4L2_FIELD_INTERLACED</code></td></tr><tr><td valign="top"><code class="constant">V4L2_FMT_FLAG_TOPFIELD</code>
= <code class="constant">V4L2_FMT_FLAG_ODDFIELD</code></td><td valign="top"><code class="constant">V4L2_FIELD_TOP</code></td></tr><tr><td valign="top"><code class="constant">V4L2_FMT_FLAG_BOTFIELD</code>
= <code class="constant">V4L2_FMT_FLAG_EVENFIELD</code></td><td valign="top"><code class="constant">V4L2_FIELD_BOTTOM</code></td></tr><tr><td valign="top"><code class="constant">-</code></td><td valign="top"><code class="constant">V4L2_FIELD_SEQ_TB</code></td></tr><tr><td valign="top"><code class="constant">-</code></td><td valign="top"><code class="constant">V4L2_FIELD_SEQ_BT</code></td></tr><tr><td valign="top"><code class="constant">-</code></td><td valign="top"><code class="constant">V4L2_FIELD_ALTERNATE</code></td></tr></tbody></table></div><p>The color space flags were replaced by a
enum <a class="link" href="ch02s02.html#v4l2-colorspace" title="Table 2.2. enum v4l2_colorspace">v4l2_colorspace</a> value in a newly added
<em class="structfield"><code>colorspace</code></em> field, where one of
<code class="constant">V4L2_COLORSPACE_SMPTE170M</code>,
<code class="constant">V4L2_COLORSPACE_BT878</code>,
<code class="constant">V4L2_COLORSPACE_470_SYSTEM_M</code> or
<code class="constant">V4L2_COLORSPACE_470_SYSTEM_BG</code> replaces
<code class="constant">V4L2_FMT_CS_601YUV</code>.</p></li><li class="listitem"><p>In struct <a class="link" href="re59.html#v4l2-requestbuffers" title="Table A.72. struct v4l2_requestbuffers">v4l2_requestbuffers</a> the
<em class="structfield"><code>type</code></em> field was properly defined as
enum <a class="link" href="ch03s05.html#v4l2-buf-type" title="Table 3.2. enum v4l2_buf_type">v4l2_buf_type</a>. Buffer types changed as mentioned above. A new
<em class="structfield"><code>memory</code></em> field of type enum <a class="link" href="ch03s05.html#v4l2-memory" title="Table 3.4. enum v4l2_memory">v4l2_memory</a> was
added to distinguish between I/O methods using buffers allocated
by the driver or the application. See <a class="xref" href="ch03.html" title="Chapter 3. Input/Output">Chapter 3, <i>Input/Output</i></a> for
details.</p></li><li class="listitem"><p>In struct <a class="link" href="ch03s05.html#v4l2-buffer" title="Table 3.1. struct v4l2_buffer">v4l2_buffer</a> the <em class="structfield"><code>type</code></em>
field was properly defined as enum <a class="link" href="ch03s05.html#v4l2-buf-type" title="Table 3.2. enum v4l2_buf_type">v4l2_buf_type</a>. Buffer types changed as
mentioned above. A <em class="structfield"><code>field</code></em> field of type
enum <a class="link" href="ch03s06.html#v4l2-field" title="Table 3.8. enum v4l2_field">v4l2_field</a> was added to indicate if a buffer contains a top or
bottom field. The old field flags were removed. Since no unadjusted
system time clock was added to the kernel as planned, the
<em class="structfield"><code>timestamp</code></em> field changed back from type
stamp_t, an unsigned 64 bit integer expressing the sample time in
nanoseconds, to struct <span class="structname">timeval</span>. With the
addition of a second memory mapping method the
<em class="structfield"><code>offset</code></em> field moved into union
<em class="structfield"><code>m</code></em>, and a new
<em class="structfield"><code>memory</code></em> field of type enum <a class="link" href="ch03s05.html#v4l2-memory" title="Table 3.4. enum v4l2_memory">v4l2_memory</a> was
added to distinguish between I/O methods. See <a class="xref" href="ch03.html" title="Chapter 3. Input/Output">Chapter 3, <i>Input/Output</i></a>
for details.</p><p>The <code class="constant">V4L2_BUF_REQ_CONTIG</code>
flag was used by the V4L compatibility layer, after changes to this
code it was no longer needed. The
<code class="constant">V4L2_BUF_ATTR_DEVICEMEM</code> flag would indicate if
the buffer was indeed allocated in device memory rather than DMA-able
system memory. It was barely useful and so was removed.</p></li><li class="listitem"><p>In struct <a class="link" href="re40.html#v4l2-framebuffer" title="Table A.43. struct v4l2_framebuffer">v4l2_framebuffer</a> the
<em class="structfield"><code>base[3]</code></em> array anticipating double- and
triple-buffering in off-screen video memory, however without defining
a synchronization mechanism, was replaced by a single pointer. The
<code class="constant">V4L2_FBUF_CAP_SCALEUP</code> and
<code class="constant">V4L2_FBUF_CAP_SCALEDOWN</code> flags were removed.
Applications can determine this capability more accurately using the
new cropping and scaling interface. The
<code class="constant">V4L2_FBUF_CAP_CLIPPING</code> flag was replaced by
<code class="constant">V4L2_FBUF_CAP_LIST_CLIPPING</code> and
<code class="constant">V4L2_FBUF_CAP_BITMAP_CLIPPING</code>.</p></li><li class="listitem"><p>In struct <a class="link" href="ch04s02.html#v4l2-clip" title="Table 4.2. struct v4l2_clip">v4l2_clip</a> the <em class="structfield"><code>x</code></em>,
<em class="structfield"><code>y</code></em>, <em class="structfield"><code>width</code></em> and
<em class="structfield"><code>height</code></em> field moved into a
<em class="structfield"><code>c</code></em> substructure of type struct <a class="link" href="ch04s02.html#v4l2-rect" title="Table 4.3. struct v4l2_rect">v4l2_rect</a>. The
<em class="structfield"><code>x</code></em> and <em class="structfield"><code>y</code></em> fields
were renamed to <em class="structfield"><code>left</code></em> and
<em class="structfield"><code>top</code></em>, i. e. offsets to a context dependent
origin.</p></li><li class="listitem"><p>In struct <a class="link" href="ch04s02.html#v4l2-window" title="Table 4.1. struct v4l2_window">v4l2_window</a> the <em class="structfield"><code>x</code></em>,
<em class="structfield"><code>y</code></em>, <em class="structfield"><code>width</code></em> and
<em class="structfield"><code>height</code></em> field moved into a
<em class="structfield"><code>w</code></em> substructure as above. A
<em class="structfield"><code>field</code></em> field of type %v4l2-field; was added
to distinguish between field and frame (interlaced) overlay.</p></li><li class="listitem"><p>The digital zoom interface, including struct
<span class="structname">v4l2_zoomcap</span>, struct
<span class="structname">v4l2_zoom</span>,
<code class="constant">V4L2_ZOOM_NONCAP</code> and
<code class="constant">V4L2_ZOOM_WHILESTREAMING</code> was replaced by a new
cropping and scaling interface. The previously unused struct
<span class="structname">v4l2_cropcap</span> and
<span class="structname">v4l2_crop</span> where redefined for this purpose.
See <a class="xref" href="ch01s11.html" title="Image Cropping, Insertion and Scaling">the section called “Image Cropping, Insertion and Scaling”</a> for details.</p></li><li class="listitem"><p>In struct <a class="link" href="ch04s07.html#v4l2-vbi-format" title="Table 4.4. struct v4l2_vbi_format">v4l2_vbi_format</a> the
<em class="structfield"><code>SAMPLE_FORMAT</code></em> field now contains a
four-character-code as used to identify video image formats and
<code class="constant">V4L2_PIX_FMT_GREY</code> replaces the
<code class="constant">V4L2_VBI_SF_UBYTE</code> define. The
<em class="structfield"><code>reserved</code></em> field was extended.</p></li><li class="listitem"><p>In struct <a class="link" href="re47.html#v4l2-captureparm" title="Table A.53. struct v4l2_captureparm">v4l2_captureparm</a> the type of the
<em class="structfield"><code>timeperframe</code></em> field changed from unsigned
long to struct <a class="link" href="re33.html#v4l2-fract" title="Table A.28. struct v4l2_fract">v4l2_fract</a>. This allows the accurate expression of multiples
of the NTSC-M frame rate 30000 / 1001. A new field
<em class="structfield"><code>readbuffers</code></em> was added to control the driver
behaviour in read I/O mode.</p><p>Similar changes were made to struct <a class="link" href="re47.html#v4l2-outputparm" title="Table A.54. struct v4l2_outputparm">v4l2_outputparm</a>.</p></li><li class="listitem"><p>The struct <span class="structname">v4l2_performance</span>
and <code class="constant">VIDIOC_G_PERF</code> ioctl were dropped. Except when
using the <a class="link" href="ch03.html#rw" title="Read/Write">read/write I/O method</a>, which is
limited anyway, this information is already available to
applications.</p></li><li class="listitem"><p>The example transformation from RGB to YCbCr color
space in the old V4L2 documentation was inaccurate, this has been
corrected in <a class="xref" href="ch02.html" title="Chapter 2. Image Formats">Chapter 2, <i>Image Formats</i></a>.</p></li></ol></div></div><div class="section" title="V4L2 2003-06-19"><div class="titlepage"><div><div><h3 class="title"><a id="id2673058"></a>V4L2 2003-06-19</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>A new capability flag
<code class="constant">V4L2_CAP_RADIO</code> was added for radio devices. Prior
to this change radio devices would identify solely by having exactly one
tuner whose type field reads <code class="constant">V4L2_TUNER_RADIO</code>.</p></li><li class="listitem"><p>An optional driver access priority mechanism was
added, see <a class="xref" href="ch01s03.html" title="Application Priority">the section called “Application Priority”</a> for details.</p></li><li class="listitem"><p>The audio input and output interface was found to be
incomplete.</p><p>Previously the <a class="link" href="re34.html" title="ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO"><code class="constant">VIDIOC_G_AUDIO</code></a>
ioctl would enumerate the available audio inputs. An ioctl to
determine the current audio input, if more than one combines with the
current video input, did not exist. So
<code class="constant">VIDIOC_G_AUDIO</code> was renamed to
<code class="constant">VIDIOC_G_AUDIO_OLD</code>, this ioctl will be removed in
the future. The <a class="link" href="re26.html" title="ioctl VIDIOC_ENUMAUDIO"><code class="constant">VIDIOC_ENUMAUDIO</code></a> ioctl was added to enumerate
audio inputs, while <a class="link" href="re34.html" title="ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO"><code class="constant">VIDIOC_G_AUDIO</code></a> now reports the current audio
input.</p><p>The same changes were made to <a class="link" href="re35.html" title="ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT"><code class="constant">VIDIOC_G_AUDOUT</code></a> and
<a class="link" href="re27.html" title="ioctl VIDIOC_ENUMAUDOUT"><code class="constant">VIDIOC_ENUMAUDOUT</code></a>.</p><p>Until further the "videodev" module will automatically
translate between the old and new ioctls, but drivers and applications
must be updated to successfully compile again.</p></li><li class="listitem"><p>The <a class="link" href="re53.html" title="ioctl VIDIOC_OVERLAY"><code class="constant">VIDIOC_OVERLAY</code></a> ioctl was incorrectly defined with
write-read parameter. It was changed to write-only, while the write-read
version was renamed to <code class="constant">VIDIOC_OVERLAY_OLD</code>. The old
ioctl will be removed in the future. Until further the "videodev"
kernel module will automatically translate to the new version, so drivers
must be recompiled, but not applications.</p></li><li class="listitem"><p><a class="xref" href="ch04s02.html" title="Video Overlay Interface">the section called “Video Overlay Interface”</a> incorrectly stated that
clipping rectangles define regions where the video can be seen.
Correct is that clipping rectangles define regions where
<span class="emphasis"><em>no</em></span> video shall be displayed and so the graphics
surface can be seen.</p></li><li class="listitem"><p>The <a class="link" href="re47.html" title="ioctl VIDIOC_G_PARM, VIDIOC_S_PARM"><code class="constant">VIDIOC_S_PARM</code></a> and <a class="link" href="re37.html" title="ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL"><code class="constant">VIDIOC_S_CTRL</code></a> ioctls were
defined with write-only parameter, inconsistent with other ioctls
modifying their argument. They were changed to write-read, while a
<code class="constant">_OLD</code> suffix was added to the write-only versions.
The old ioctls will be removed in the future. Drivers and
applications assuming a constant parameter need an update.</p></li></ol></div></div><div class="section" title="V4L2 2003-11-05"><div class="titlepage"><div><div><h3 class="title"><a id="id2673241"></a>V4L2 2003-11-05</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>In <a class="xref" href="ch02s04.html" title="RGB Formats">the section called “RGB Formats”</a> the following pixel
formats were incorrectly transferred from Bill Dirks' V4L2
specification. Descriptions below refer to bytes in memory, in
ascending address order.</p><div class="informaltable"><table border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th>Symbol</th><th>In this document prior to revision
0.5</th><th>Corrected</th></tr></thead><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_PIX_FMT_RGB24</code></td><td valign="top">B, G, R</td><td valign="top">R, G, B</td></tr><tr><td valign="top"><code class="constant">V4L2_PIX_FMT_BGR24</code></td><td valign="top">R, G, B</td><td valign="top">B, G, R</td></tr><tr><td valign="top"><code class="constant">V4L2_PIX_FMT_RGB32</code></td><td valign="top">B, G, R, X</td><td valign="top">R, G, B, X</td></tr><tr><td valign="top"><code class="constant">V4L2_PIX_FMT_BGR32</code></td><td valign="top">R, G, B, X</td><td valign="top">B, G, R, X</td></tr></tbody></table></div><p> The
<code class="constant">V4L2_PIX_FMT_BGR24</code> example was always
correct.</p><p>In <a class="xref" href="ch07.html#v4l-image-properties" title="Image Properties">the section called “Image Properties”</a> the mapping
of the V4L <code class="constant">VIDEO_PALETTE_RGB24</code> and
<code class="constant">VIDEO_PALETTE_RGB32</code> formats to V4L2 pixel formats
was accordingly corrected.</p></li><li class="listitem"><p>Unrelated to the fixes above, drivers may still
interpret some V4L2 RGB pixel formats differently. These issues have
yet to be addressed, for details see <a class="xref" href="ch02s04.html" title="RGB Formats">the section called “RGB Formats”</a>.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.6, 2004-05-09"><div class="titlepage"><div><div><h3 class="title"><a id="id2673398"></a>V4L2 in Linux 2.6.6, 2004-05-09</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The <a class="link" href="re22.html" title="ioctl VIDIOC_CROPCAP"><code class="constant">VIDIOC_CROPCAP</code></a> ioctl was incorrectly defined
with read-only parameter. It is now defined as write-read ioctl, while
the read-only version was renamed to
<code class="constant">VIDIOC_CROPCAP_OLD</code>. The old ioctl will be removed
in the future.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.8"><div class="titlepage"><div><div><h3 class="title"><a id="id2673433"></a>V4L2 in Linux 2.6.8</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>A new field <em class="structfield"><code>input</code></em> (former
<em class="structfield"><code>reserved[0]</code></em>) was added to the struct <a class="link" href="ch03s05.html#v4l2-buffer" title="Table 3.1. struct v4l2_buffer">v4l2_buffer</a>
structure. Purpose of this field is to alternate between video inputs
(e. g. cameras) in step with the video capturing process. This function
must be enabled with the new <code class="constant">V4L2_BUF_FLAG_INPUT</code>
flag. The <em class="structfield"><code>flags</code></em> field is no longer
read-only.</p></li></ol></div></div><div class="section" title="V4L2 spec erratum 2004-08-01"><div class="titlepage"><div><div><h3 class="title"><a id="id2673480"></a>V4L2 spec erratum 2004-08-01</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The return value of the
<a class="xref" href="re64.html" title="V4L2 open()"><span class="refentrytitle">V4L2 open()</span>(2)</a> function was incorrectly documented.</p></li><li class="listitem"><p>Audio output ioctls end in -AUDOUT, not -AUDIOOUT.</p></li><li class="listitem"><p>In the Current Audio Input example the
<code class="constant">VIDIOC_G_AUDIO</code> ioctl took the wrong
argument.</p></li><li class="listitem"><p>The documentation of the <a class="link" href="re54.html" title="ioctl VIDIOC_QBUF, VIDIOC_DQBUF"><code class="constant">VIDIOC_QBUF</code></a> and
<a class="link" href="re54.html" title="ioctl VIDIOC_QBUF, VIDIOC_DQBUF"><code class="constant">VIDIOC_DQBUF</code></a> ioctls did not mention the struct <a class="link" href="ch03s05.html#v4l2-buffer" title="Table 3.1. struct v4l2_buffer">v4l2_buffer</a>
<em class="structfield"><code>memory</code></em> field. It was also missing from
examples. Also on the <code class="constant">VIDIOC_DQBUF</code> page the <span class="errorcode">EIO</span> error code
was not documented.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.14"><div class="titlepage"><div><div><h3 class="title"><a id="id2673559"></a>V4L2 in Linux 2.6.14</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>A new sliced VBI interface was added. It is documented
in <a class="xref" href="ch04s08.html" title="Sliced VBI Data Interface">the section called “Sliced VBI Data Interface”</a> and replaces the interface first
proposed in V4L2 specification 0.8.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.15"><div class="titlepage"><div><div><h3 class="title"><a id="id2673599"></a>V4L2 in Linux 2.6.15</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The <a class="link" href="re52.html" title="ioctl VIDIOC_LOG_STATUS"><code class="constant">VIDIOC_LOG_STATUS</code></a> ioctl was added.</p></li><li class="listitem"><p>New video standards
<code class="constant">V4L2_STD_NTSC_443</code>,
<code class="constant">V4L2_STD_SECAM_LC</code>,
<code class="constant">V4L2_STD_SECAM_DK</code> (a set of SECAM D, K and K1),
and <code class="constant">V4L2_STD_ATSC</code> (a set of
<code class="constant">V4L2_STD_ATSC_8_VSB</code> and
<code class="constant">V4L2_STD_ATSC_16_VSB</code>) were defined. Note the
<code class="constant">V4L2_STD_525_60</code> set now includes
<code class="constant">V4L2_STD_NTSC_443</code>. See also <a class="xref" href="re33.html#v4l2-std-id" title="Table A.29. typedef v4l2_std_id">Table A.29, “typedef <span class="structname">v4l2_std_id</span>”</a>.</p></li><li class="listitem"><p>The <code class="constant">VIDIOC_G_COMP</code> and
<code class="constant">VIDIOC_S_COMP</code> ioctl were renamed to
<code class="constant">VIDIOC_G_MPEGCOMP</code> and
<code class="constant">VIDIOC_S_MPEGCOMP</code> respectively. Their argument
was replaced by a struct
<span class="structname">v4l2_mpeg_compression</span> pointer. (The
<code class="constant">VIDIOC_G_MPEGCOMP</code> and
<code class="constant">VIDIOC_S_MPEGCOMP</code> ioctls where removed in Linux
2.6.25.)</p></li></ol></div></div><div class="section" title="V4L2 spec erratum 2005-11-27"><div class="titlepage"><div><div><h3 class="title"><a id="id2673710"></a>V4L2 spec erratum 2005-11-27</h3></div></div></div><p>The capture example in <a class="xref" href="apc.html" title="Appendix C. Video Capture Example">Appendix C, <i>Video Capture Example</i></a>
called the <a class="link" href="re36.html" title="ioctl VIDIOC_G_CROP, VIDIOC_S_CROP"><code class="constant">VIDIOC_S_CROP</code></a> ioctl without checking if cropping is
supported. In the video standard selection example in
<a class="xref" href="ch01s07.html" title="Video Standards">the section called “Video Standards”</a> the <a class="link" href="re50.html" title="ioctl VIDIOC_G_STD, VIDIOC_S_STD"><code class="constant">VIDIOC_S_STD</code></a> call used the wrong
argument type.</p></div><div class="section" title="V4L2 spec erratum 2006-01-10"><div class="titlepage"><div><div><h3 class="title"><a id="id2673750"></a>V4L2 spec erratum 2006-01-10</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The <code class="constant">V4L2_IN_ST_COLOR_KILL</code> flag in
struct <a class="link" href="re31.html#v4l2-input" title="Table A.22. struct v4l2_input">v4l2_input</a> not only indicates if the color killer is enabled, but
also if it is active. (The color killer disables color decoding when
it detects no color in the video signal to improve the image
quality.)</p></li><li class="listitem"><p><a class="link" href="re47.html" title="ioctl VIDIOC_G_PARM, VIDIOC_S_PARM"><code class="constant">VIDIOC_S_PARM</code></a> is a write-read ioctl, not write-only as
stated on its reference page. The ioctl changed in 2003 as noted above.</p></li></ol></div></div><div class="section" title="V4L2 spec erratum 2006-02-03"><div class="titlepage"><div><div><h3 class="title"><a id="id2673800"></a>V4L2 spec erratum 2006-02-03</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>In struct <a class="link" href="re47.html#v4l2-captureparm" title="Table A.53. struct v4l2_captureparm">v4l2_captureparm</a> and struct <a class="link" href="re47.html#v4l2-outputparm" title="Table A.54. struct v4l2_outputparm">v4l2_outputparm</a> the
<em class="structfield"><code>timeperframe</code></em> field gives the time in
seconds, not microseconds.</p></li></ol></div></div><div class="section" title="V4L2 spec erratum 2006-02-04"><div class="titlepage"><div><div><h3 class="title"><a id="id2673842"></a>V4L2 spec erratum 2006-02-04</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The <em class="structfield"><code>clips</code></em> field in
struct <a class="link" href="ch04s02.html#v4l2-window" title="Table 4.1. struct v4l2_window">v4l2_window</a> must point to an array of struct <a class="link" href="ch04s02.html#v4l2-clip" title="Table 4.2. struct v4l2_clip">v4l2_clip</a>, not a linked
list, because drivers ignore the struct
<span class="structname">v4l2_clip</span>.<em class="structfield"><code>next</code></em>
pointer.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.17"><div class="titlepage"><div><div><h3 class="title"><a id="id2673890"></a>V4L2 in Linux 2.6.17</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>New video standard macros were added:
<code class="constant">V4L2_STD_NTSC_M_KR</code> (NTSC M South Korea), and the
sets <code class="constant">V4L2_STD_MN</code>,
<code class="constant">V4L2_STD_B</code>, <code class="constant">V4L2_STD_GH</code> and
<code class="constant">V4L2_STD_DK</code>. The
<code class="constant">V4L2_STD_NTSC</code> and
<code class="constant">V4L2_STD_SECAM</code> sets now include
<code class="constant">V4L2_STD_NTSC_M_KR</code> and
<code class="constant">V4L2_STD_SECAM_LC</code> respectively.</p></li><li class="listitem"><p>A new <code class="constant">V4L2_TUNER_MODE_LANG1_LANG2</code>
was defined to record both languages of a bilingual program. The
use of <code class="constant">V4L2_TUNER_MODE_STEREO</code> for this purpose
is deprecated now. See the <a class="link" href="re51.html" title="ioctl VIDIOC_G_TUNER, VIDIOC_S_TUNER"><code class="constant">VIDIOC_G_TUNER</code></a> section for
details.</p></li></ol></div></div><div class="section" title="V4L2 spec erratum 2006-09-23 (Draft 0.15)"><div class="titlepage"><div><div><h3 class="title"><a id="id2673969"></a>V4L2 spec erratum 2006-09-23 (Draft 0.15)</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>In various places
<code class="constant">V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</code> and
<code class="constant">V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</code> of the sliced VBI
interface were not mentioned along with other buffer types.</p></li><li class="listitem"><p>In <a class="xref" href="re34.html" title="ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO"><span class="refentrytitle">ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO</span>(2)</a> it was clarified
that the struct <a class="link" href="re34.html#v4l2-audio" title="Table A.31. struct v4l2_audio">v4l2_audio</a> <em class="structfield"><code>mode</code></em> field is a flags
field.</p></li><li class="listitem"><p><a class="xref" href="re56.html" title="ioctl VIDIOC_QUERYCAP"><span class="refentrytitle">ioctl VIDIOC_QUERYCAP</span>(2)</a> did not mention the
sliced VBI and radio capability flags.</p></li><li class="listitem"><p>In <a class="xref" href="re42.html" title="ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY"><span class="refentrytitle">ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY</span>(2)</a> it was
clarified that applications must initialize the tuner
<em class="structfield"><code>type</code></em> field of struct <a class="link" href="re42.html#v4l2-frequency" title="Table A.47. struct v4l2_frequency">v4l2_frequency</a> before
calling <a class="link" href="re42.html" title="ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY"><code class="constant">VIDIOC_S_FREQUENCY</code></a>.</p></li><li class="listitem"><p>The <em class="structfield"><code>reserved</code></em> array
in struct <a class="link" href="re59.html#v4l2-requestbuffers" title="Table A.72. struct v4l2_requestbuffers">v4l2_requestbuffers</a> has 2 elements, not 32.</p></li><li class="listitem"><p>In <a class="xref" href="ch04s03.html" title="Video Output Interface">the section called “Video Output Interface”</a> and <a class="xref" href="ch04s07.html" title="Raw VBI Data Interface">the section called “Raw VBI Data Interface”</a> the device file names
<code class="filename">/dev/vout</code> which never caught on were replaced
by <code class="filename">/dev/video</code>.</p></li><li class="listitem"><p>With Linux 2.6.15 the possible range for VBI device minor
numbers was extended from 224-239 to 224-255. Accordingly device file names
<code class="filename">/dev/vbi0</code> to <code class="filename">/dev/vbi31</code> are
possible now.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.18"><div class="titlepage"><div><div><h3 class="title"><a id="id2674140"></a>V4L2 in Linux 2.6.18</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>New ioctls <a class="link" href="re39.html" title="ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS"><code class="constant">VIDIOC_G_EXT_CTRLS</code></a>, <a class="link" href="re39.html" title="ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS"><code class="constant">VIDIOC_S_EXT_CTRLS</code></a>
and <a class="link" href="re39.html" title="ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS"><code class="constant">VIDIOC_TRY_EXT_CTRLS</code></a> were added, a flag to skip unsupported
controls with <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a>, new control types
<code class="constant">V4L2_CTRL_TYPE_INTEGER64</code> and
<code class="constant">V4L2_CTRL_TYPE_CTRL_CLASS</code> (<a class="xref" href="re57.html#v4l2-ctrl-type" title="Table A.70. enum v4l2_ctrl_type">Table A.70, “enum v4l2_ctrl_type”</a>), and new control flags
<code class="constant">V4L2_CTRL_FLAG_READ_ONLY</code>,
<code class="constant">V4L2_CTRL_FLAG_UPDATE</code>,
<code class="constant">V4L2_CTRL_FLAG_INACTIVE</code> and
<code class="constant">V4L2_CTRL_FLAG_SLIDER</code> (<a class="xref" href="re57.html#control-flags" title="Table A.71. Control Flags">Table A.71, “Control Flags”</a>). See <a class="xref" href="ch01s09.html" title="Extended Controls">the section called “Extended Controls”</a> for details.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.19"><div class="titlepage"><div><div><h3 class="title"><a id="id2674234"></a>V4L2 in Linux 2.6.19</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>In struct <a class="link" href="re49.html#v4l2-sliced-vbi-cap" title="Table A.58. struct v4l2_sliced_vbi_cap">v4l2_sliced_vbi_cap</a> a buffer type field was added
replacing a reserved field. Note on architectures where the size of
enum types differs from int types the size of the structure changed.
The <a class="link" href="re49.html" title="ioctl VIDIOC_G_SLICED_VBI_CAP"><code class="constant">VIDIOC_G_SLICED_VBI_CAP</code></a> ioctl was redefined from being read-only
to write-read. Applications must initialize the type field and clear
the reserved fields now. These changes may <span class="emphasis"><em>break the
compatibility</em></span> with older drivers and applications.</p></li><li class="listitem"><p>The ioctls <a class="link" href="re29.html" title="ioctl VIDIOC_ENUM_FRAMESIZES"><code class="constant">VIDIOC_ENUM_FRAMESIZES</code></a> and
<a class="link" href="re30.html" title="ioctl VIDIOC_ENUM_FRAMEINTERVALS"><code class="constant">VIDIOC_ENUM_FRAMEINTERVALS</code></a> were added.</p></li><li class="listitem"><p>A new pixel format <code class="constant">V4L2_PIX_FMT_RGB444</code> (<a class="xref" href="re01.html#rgb-formats" title="Table 2.4. Packed RGB Image Formats">Table 2.4, “Packed RGB Image Formats”</a>) was added.</p></li></ol></div></div><div class="section" title="V4L2 spec erratum 2006-10-12 (Draft 0.17)"><div class="titlepage"><div><div><h3 class="title"><a id="id2674320"></a>V4L2 spec erratum 2006-10-12 (Draft 0.17)</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><code class="constant">V4L2_PIX_FMT_HM12</code> (<a class="xref" href="ch02s07.html#reserved-formats" title="Table 2.8. Reserved Image Formats">Table 2.8, “Reserved Image Formats”</a>) is a YUV 4:2:0, not 4:2:2 format.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.21"><div class="titlepage"><div><div><h3 class="title"><a id="id2674351"></a>V4L2 in Linux 2.6.21</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The <code class="filename">videodev2.h</code> header file is
now dual licensed under GNU General Public License version two or
later, and under a 3-clause BSD-style license.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.22"><div class="titlepage"><div><div><h3 class="title"><a id="id2674381"></a>V4L2 in Linux 2.6.22</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Two new field orders
<code class="constant">V4L2_FIELD_INTERLACED_TB</code> and
<code class="constant">V4L2_FIELD_INTERLACED_BT</code> were
added. See <a class="xref" href="ch03s06.html#v4l2-field" title="Table 3.8. enum v4l2_field">Table 3.8, “enum v4l2_field”</a> for details.</p></li><li class="listitem"><p>Three new clipping/blending methods with a global or
straight or inverted local alpha value were added to the video overlay
interface. See the description of the <a class="link" href="re40.html" title="ioctl VIDIOC_G_FBUF, VIDIOC_S_FBUF"><code class="constant">VIDIOC_G_FBUF</code></a> and
<a class="link" href="re40.html" title="ioctl VIDIOC_G_FBUF, VIDIOC_S_FBUF"><code class="constant">VIDIOC_S_FBUF</code></a> ioctls for details.</p><p>A new <em class="structfield"><code>global_alpha</code></em> field
was added to <a class="link" href="ch04s02.html#v4l2-window" title="Table 4.1. struct v4l2_window"><span class="structname">v4l2_window</span></a>,
extending the structure. This may <span class="emphasis"><em>break
compatibility</em></span> with applications using a struct
<span class="structname">v4l2_window</span> directly. However the <a class="link" href="re41.html" title="ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT">VIDIOC_G/S/TRY_FMT</a> ioctls, which take a
pointer to a <a class="link" href="re41.html#v4l2-format" title="Table A.46. struct v4l2_format">v4l2_format</a> parent
structure with padding bytes at the end, are not affected.</p></li><li class="listitem"><p>The format of the <em class="structfield"><code>chromakey</code></em>
field in struct <a class="link" href="ch04s02.html#v4l2-window" title="Table 4.1. struct v4l2_window">v4l2_window</a> changed from "host order RGB32" to a pixel
value in the same format as the framebuffer. This may <span class="emphasis"><em>break
compatibility</em></span> with existing applications. Drivers
supporting the "host order RGB32" format are not known.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.24"><div class="titlepage"><div><div><h3 class="title"><a id="id2674505"></a>V4L2 in Linux 2.6.24</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The pixel formats
<code class="constant">V4L2_PIX_FMT_PAL8</code>,
<code class="constant">V4L2_PIX_FMT_YUV444</code>,
<code class="constant">V4L2_PIX_FMT_YUV555</code>,
<code class="constant">V4L2_PIX_FMT_YUV565</code> and
<code class="constant">V4L2_PIX_FMT_YUV32</code> were added.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.25"><div class="titlepage"><div><div><h3 class="title"><a id="id2674545"></a>V4L2 in Linux 2.6.25</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The pixel formats <a class="link" href="re08.html" title="V4L2_PIX_FMT_Y16 ('Y16 ')">
<code class="constant">V4L2_PIX_FMT_Y16</code></a> and <a class="link" href="re05.html" title="V4L2_PIX_FMT_SBGGR16 ('BYR2')">
<code class="constant">V4L2_PIX_FMT_SBGGR16</code></a> were added.</p></li><li class="listitem"><p>New <a class="link" href="ch01s08.html" title="User Controls">controls</a>
<code class="constant">V4L2_CID_POWER_LINE_FREQUENCY</code>,
<code class="constant">V4L2_CID_HUE_AUTO</code>,
<code class="constant">V4L2_CID_WHITE_BALANCE_TEMPERATURE</code>,
<code class="constant">V4L2_CID_SHARPNESS</code> and
<code class="constant">V4L2_CID_BACKLIGHT_COMPENSATION</code> were added. The
controls <code class="constant">V4L2_CID_BLACK_LEVEL</code>,
<code class="constant">V4L2_CID_WHITENESS</code>,
<code class="constant">V4L2_CID_HCENTER</code> and
<code class="constant">V4L2_CID_VCENTER</code> were deprecated.
</p></li><li class="listitem"><p>A <a class="link" href="ch01s09.html#camera-controls" title="Camera Control Reference">Camera controls
class</a> was added, with the new controls
<code class="constant">V4L2_CID_EXPOSURE_AUTO</code>,
<code class="constant">V4L2_CID_EXPOSURE_ABSOLUTE</code>,
<code class="constant">V4L2_CID_EXPOSURE_AUTO_PRIORITY</code>,
<code class="constant">V4L2_CID_PAN_RELATIVE</code>,
<code class="constant">V4L2_CID_TILT_RELATIVE</code>,
<code class="constant">V4L2_CID_PAN_RESET</code>,
<code class="constant">V4L2_CID_TILT_RESET</code>,
<code class="constant">V4L2_CID_PAN_ABSOLUTE</code>,
<code class="constant">V4L2_CID_TILT_ABSOLUTE</code>,
<code class="constant">V4L2_CID_FOCUS_ABSOLUTE</code>,
<code class="constant">V4L2_CID_FOCUS_RELATIVE</code> and
<code class="constant">V4L2_CID_FOCUS_AUTO</code>.</p></li><li class="listitem"><p>The <code class="constant">VIDIOC_G_MPEGCOMP</code> and
<code class="constant">VIDIOC_S_MPEGCOMP</code> ioctls, which were superseded
by the <a class="link" href="ch01s09.html" title="Extended Controls">extended controls</a>
interface in Linux 2.6.18, where finally removed from the
<code class="filename">videodev2.h</code> header file.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.26"><div class="titlepage"><div><div><h3 class="title"><a id="id2674723"></a>V4L2 in Linux 2.6.26</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The pixel formats
<code class="constant">V4L2_PIX_FMT_Y16</code> and
<code class="constant">V4L2_PIX_FMT_SBGGR16</code> were added.</p></li><li class="listitem"><p>Added user controls
<code class="constant">V4L2_CID_CHROMA_AGC</code> and
<code class="constant">V4L2_CID_COLOR_KILLER</code>.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.27"><div class="titlepage"><div><div><h3 class="title"><a id="id2674767"></a>V4L2 in Linux 2.6.27</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The <a class="link" href="re60.html" title="ioctl VIDIOC_S_HW_FREQ_SEEK"><code class="constant">VIDIOC_S_HW_FREQ_SEEK</code></a> ioctl and the
<code class="constant">V4L2_CAP_HW_FREQ_SEEK</code> capability were added.</p></li><li class="listitem"><p>The pixel formats
<code class="constant">V4L2_PIX_FMT_YVYU</code>,
<code class="constant">V4L2_PIX_FMT_PCA501</code>,
<code class="constant">V4L2_PIX_FMT_PCA505</code>,
<code class="constant">V4L2_PIX_FMT_PCA508</code>,
<code class="constant">V4L2_PIX_FMT_PCA561</code>,
<code class="constant">V4L2_PIX_FMT_SGBRG8</code>,
<code class="constant">V4L2_PIX_FMT_PAC207</code> and
<code class="constant">V4L2_PIX_FMT_PJPG</code> were added.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.28"><div class="titlepage"><div><div><h3 class="title"><a id="id2674836"></a>V4L2 in Linux 2.6.28</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Added <code class="constant">V4L2_MPEG_AUDIO_ENCODING_AAC</code> and
<code class="constant">V4L2_MPEG_AUDIO_ENCODING_AC3</code> MPEG audio encodings.</p></li><li class="listitem"><p>Added <code class="constant">V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</code> MPEG
video encoding.</p></li><li class="listitem"><p>The pixel formats
<code class="constant">V4L2_PIX_FMT_SGRBG10</code> and
<code class="constant">V4L2_PIX_FMT_SGRBG10DPCM8</code> were added.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.29"><div class="titlepage"><div><div><h3 class="title"><a id="id2674894"></a>V4L2 in Linux 2.6.29</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>The <code class="constant">VIDIOC_G_CHIP_IDENT</code> ioctl was renamed
to <code class="constant">VIDIOC_G_CHIP_IDENT_OLD</code> and <a class="link" href="re23.html" title="ioctl VIDIOC_DBG_G_CHIP_IDENT"><code class="constant">VIDIOC_DBG_G_CHIP_IDENT</code></a>
was introduced in its place. The old struct <span class="structname">v4l2_chip_ident</span>
was renamed to <span class="structname"><a id="v4l2-chip-ident-old"></a>v4l2_chip_ident_old</span>.</p></li><li class="listitem"><p>The pixel formats
<code class="constant">V4L2_PIX_FMT_VYUY</code>,
<code class="constant">V4L2_PIX_FMT_NV16</code> and
<code class="constant">V4L2_PIX_FMT_NV61</code> were added.</p></li><li class="listitem"><p>Added camera controls
<code class="constant">V4L2_CID_ZOOM_ABSOLUTE</code>,
<code class="constant">V4L2_CID_ZOOM_RELATIVE</code>,
<code class="constant">V4L2_CID_ZOOM_CONTINUOUS</code> and
<code class="constant">V4L2_CID_PRIVACY</code>.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.30"><div class="titlepage"><div><div><h3 class="title"><a id="id2674986"></a>V4L2 in Linux 2.6.30</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>New control flag <code class="constant">V4L2_CTRL_FLAG_WRITE_ONLY</code> was added.</p></li><li class="listitem"><p>New control <code class="constant">V4L2_CID_COLORFX</code> was added.</p></li></ol></div></div><div class="section" title="V4L2 in Linux 2.6.32"><div class="titlepage"><div><div><h3 class="title"><a id="id2675021"></a>V4L2 in Linux 2.6.32</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>In order to be easier to compare a V4L2 API and a kernel
version, now V4L2 API is numbered using the Linux Kernel version numeration.</p></li><li class="listitem"><p>Finalized the RDS capture API. See <a class="xref" href="ch04s11.html" title="RDS Interface">the section called “RDS Interface”</a> for
more information.</p></li><li class="listitem"><p>Added new capabilities for modulators and RDS encoders.</p></li><li class="listitem"><p>Add description for libv4l API.</p></li><li class="listitem"><p>Added support for string controls via new type <code class="constant">V4L2_CTRL_TYPE_STRING</code>.</p></li><li class="listitem"><p>Added <code class="constant">V4L2_CID_BAND_STOP_FILTER</code> documentation.</p></li><li class="listitem"><p>Added FM Modulator (FM TX) Extended Control Class: <code class="constant">V4L2_CTRL_CLASS_FM_TX</code> and their Control IDs.</p></li><li class="listitem"><p>Added Remote Controller chapter, describing the default Remote Controller mapping for media devices.</p></li></ol></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch07.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch07.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch07s03.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 7. Changes </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Relation of V4L2 to other Linux multimedia APIs</td></tr></table></div></body></html>
