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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>The DVR device</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="ch16.html" title="Chapter 16. Examples" /><link rel="prev" href="ch16.html" title="Chapter 16. Examples" /><link rel="next" href="pt03.html" title="Part III. Other API's used by media infrastructure drivers" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">The DVR device</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch16.html">Prev</a> </td><th width="60%" align="center">Chapter 16. Examples</th><td width="20%" align="right"> <a accesskey="n" href="pt03.html">Next</a></td></tr></table><hr /></div><div class="section" title="The DVR device"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="the_dvr_device"></a>The DVR device</h2></div></div></div><p>The following program code shows how to use the DVR device for recording.
</p><pre class="programlisting">
#include <sys/ioctl.h>
#include <stdio.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <time.h>
#include <unistd.h>
#include <linux/dvb/dmx.h>
#include <linux/dvb/video.h>
#include <sys/poll.h>
#define DVR "/dev/dvb/adapter0/dvr1"
#define AUDIO "/dev/dvb/adapter0/audio1"
#define VIDEO "/dev/dvb/adapter0/video1"
#define BUFFY (188⋆20)
#define MAX_LENGTH (1024⋆1024⋆5) /⋆ record 5MB ⋆/
/⋆ switch the demuxes to recording, assuming the transponder is tuned ⋆/
/⋆ demux1, demux2: file descriptor of video and audio filters ⋆/
/⋆ vpid, apid: PIDs of video and audio channels ⋆/
int switch_to_record(int demux1, int demux2, uint16_t vpid, uint16_t apid)
{
struct dmx_pes_filter_params pesFilterParams;
if (demux1 < 0){
if ((demux1=open(DMX, O_RDWR|O_NONBLOCK))
< 0){
perror("DEMUX DEVICE: ");
return -1;
}
}
if (demux2 < 0){
if ((demux2=open(DMX, O_RDWR|O_NONBLOCK))
< 0){
perror("DEMUX DEVICE: ");
return -1;
}
}
pesFilterParams.pid = vpid;
pesFilterParams.input = DMX_IN_FRONTEND;
pesFilterParams.output = DMX_OUT_TS_TAP;
pesFilterParams.pes_type = DMX_PES_VIDEO;
pesFilterParams.flags = DMX_IMMEDIATE_START;
if (ioctl(demux1, DMX_SET_PES_FILTER, &pesFilterParams) < 0){
perror("DEMUX DEVICE");
return -1;
}
pesFilterParams.pid = apid;
pesFilterParams.input = DMX_IN_FRONTEND;
pesFilterParams.output = DMX_OUT_TS_TAP;
pesFilterParams.pes_type = DMX_PES_AUDIO;
pesFilterParams.flags = DMX_IMMEDIATE_START;
if (ioctl(demux2, DMX_SET_PES_FILTER, &pesFilterParams) < 0){
perror("DEMUX DEVICE");
return -1;
}
return 0;
}
/⋆ start recording MAX_LENGTH , assuming the transponder is tuned ⋆/
/⋆ demux1, demux2: file descriptor of video and audio filters ⋆/
/⋆ vpid, apid: PIDs of video and audio channels ⋆/
int record_dvr(int demux1, int demux2, uint16_t vpid, uint16_t apid)
{
int i;
int len;
int written;
uint8_t buf[BUFFY];
uint64_t length;
struct pollfd pfd[1];
int dvr, dvr_out;
/⋆ open dvr device ⋆/
if ((dvr = open(DVR, O_RDONLY|O_NONBLOCK)) < 0){
perror("DVR DEVICE");
return -1;
}
/⋆ switch video and audio demuxes to dvr ⋆/
printf ("Switching dvr on\n");
i = switch_to_record(demux1, demux2, vpid, apid);
printf("finished: ");
printf("Recording %2.0f MB of test file in TS format\n",
MAX_LENGTH/(1024.0⋆1024.0));
length = 0;
/⋆ open output file ⋆/
if ((dvr_out = open(DVR_FILE,O_WRONLY|O_CREAT
|O_TRUNC, S_IRUSR|S_IWUSR
|S_IRGRP|S_IWGRP|S_IROTH|
S_IWOTH)) < 0){
perror("Can't open file for dvr test");
return -1;
}
pfd[0].fd = dvr;
pfd[0].events = POLLIN;
/⋆ poll for dvr data and write to file ⋆/
while (length < MAX_LENGTH ) {
if (poll(pfd,1,1)){
if (pfd[0].revents & POLLIN){
len = read(dvr, buf, BUFFY);
if (len < 0){
perror("recording");
return -1;
}
if (len > 0){
written = 0;
while (written < len)
written +=
write (dvr_out,
buf, len);
length += len;
printf("written %2.0f MB\r",
length/1024./1024.);
}
}
}
}
return 0;
}
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