From e2821f4bce9db15fcb463ba945fe7433773b9901 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Mon, 23 Apr 2012 23:18:24 +0200
Subject: [PATCH 05/12] libv4lconvert: Drop Pixart JPEG frames with changing
 chrominance setting

Sometimes the pac7302 switches chrominance setting halfway though a
frame, with a quite ugly looking result, so lets drop such frames.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 lib/libv4lconvert/tinyjpeg-internal.h |    1 +
 lib/libv4lconvert/tinyjpeg.c          |   11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/lib/libv4lconvert/tinyjpeg-internal.h b/lib/libv4lconvert/tinyjpeg-internal.h
index 4041251..dcbcf27 100644
--- a/lib/libv4lconvert/tinyjpeg-internal.h
+++ b/lib/libv4lconvert/tinyjpeg-internal.h
@@ -104,6 +104,7 @@ struct jdec_private {
 	unsigned int current_cid;			/* For planar JPEG */
 #endif
 	unsigned char marker;			/* for PJPG (Pixart JPEG) */
+	unsigned char first_marker;		/* for PJPG (Pixart JPEG) */
 
 	/* Temp space used after the IDCT to store each components */
 	uint8_t Y[64 * 4], Cr[64], Cb[64];
diff --git a/lib/libv4lconvert/tinyjpeg.c b/lib/libv4lconvert/tinyjpeg.c
index dd77d0f..8fc484e 100644
--- a/lib/libv4lconvert/tinyjpeg.c
+++ b/lib/libv4lconvert/tinyjpeg.c
@@ -1387,6 +1387,16 @@ static void pixart_decode_MCU_2x1_3planes(struct jdec_private *priv)
 	look_nbits(priv->reservoir, priv->nbits_in_reservoir, priv->stream,
 		   8, marker);
 
+	/* Sometimes the pac7302 switches chrominance setting halfway though a
+	   frame, with a quite ugly looking result, so we drop such frames. */
+	if (priv->first_marker == 0)
+		priv->first_marker = marker;
+	else if ((marker & 0x80) != (priv->first_marker & 0x80)) {
+		snprintf(priv->error_string, sizeof(priv->error_string),
+			"Pixart JPEG error: chrominance changed halfway\n");
+		longjmp(priv->jump_state, -EIO);
+	}
+
 	/* Pixart JPEG MCU-s are preceded by a marker indicating the quality
 	   setting with which the MCU is compressed, IOW the MCU-s may have a
 	   different quantization table per MCU. So if the marker changes we
@@ -2224,6 +2234,7 @@ int tinyjpeg_decode(struct jdec_private *priv, int pixfmt)
 			return length;
 		priv->stream = priv->stream_filtered;
 		priv->stream_end = priv->stream + length;
+		priv->first_marker = 0;
 
 		decode_mcu_table = pixart_decode_mcu_3comp_table;
 	}
-- 
1.7.10