[FFmpeg-cvslog] screenpresso: Correctly handle keyframes

[Vittorio Giovara]

ffmpeg | branch: master | Vittorio Giovara <vittorio.giovara at gmail.com> | Tue Mar 29 20:30:48 2016 +0200| [ec8a69fab657f9cce624e8b0f4069d12696890bf] | committer: Vittorio Giovara

screenpresso: Correctly handle keyframes

The first byte contains compression level together with keyframe status.
When a frame is not interpreted correctly, its data is summed to the
reference, and would degrade over time, producing an incorrect result.

Signed-off-by: Vittorio Giovara <vittorio.giovara at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ec8a69fab657f9cce624e8b0f4069d12696890bf
---

 libavcodec/screenpresso.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/libavcodec/screenpresso.c b/libavcodec/screenpresso.c
index 41d1755..819bd60 100644
--- a/libavcodec/screenpresso.c
+++ b/libavcodec/screenpresso.c
@@ -115,10 +115,9 @@ static int screenpresso_decode_frame(AVCodecContext *avctx, void *data,
         return AVERROR_INVALIDDATA;
     }
 
-    /* Basic sanity check, but not really harmful */
-    if (avpkt->data[0] != 0x73 && avpkt->data[0] != 0x72)
-        av_log(avctx, AV_LOG_WARNING, "Unknown header 0x%02X\n", avpkt->data[0]);
-    keyframe = (avpkt->data[0] == 0x73);
+    /* Compression level (4 bits) and keyframe information (1 bit) */
+    av_log(avctx, AV_LOG_DEBUG, "Compression level %d\n", avpkt->data[0] >> 4);
+    keyframe = avpkt->data[0] & 1;
 
     /* Pixel size */
     component_size = ((avpkt->data[1] >> 2) & 0x03) + 1;