[FFmpeg-devel] [PATCH v3] H.264: reinitialize context on aspect ratio change as well

[Janusz Krzysztofik]

While using ffmpeg based vdr softdevice plugin for watching h.264 encoded live 
tv, I found that after correct picture aspect ratio setup on a new stream 
startup, any following picture aspect ratio changes were not processed. The 
same applies to playing vdr caputured samples of this transmission with 
ffplay.

This patch corrects the problem for me by reinitializing the decoder context 
on every valid aspect ratio change, not only size changes.

Created against ffmpeg svn revision 22110 dated 2010-02-28.
Tested using this revision ffplay on x86_64.

Signed-off-by: Janusz Krzysztofik <jkrzyszt at tis.icnet.pl>

---
Hi,

I'v noticed that there were problems with the previous version of this patch 
and it has been reverted.

This version should correct this problem, I've tested it successfully with 
every sample from http://samples.ffmpeg.org/V-codecs/h264/ that also played 
for me without the patch.

Thanks,
Janusz


--- trunk/libavcodec/h264.c.orig	2010-03-03 22:57:53.000000000 +0100
+++ trunk/libavcodec/h264.c	2010-03-03 23:20:44.000000000 +0100
@@ -1774,7 +1774,11 @@ static int decode_slice_header(H264Conte
         s->height= 16*s->mb_height - 4*FFMIN(h->sps.crop_bottom, 3);
 
     if (s->context_initialized
-        && (   s->width != s->avctx->width || s->height != s->avctx->height)) {
+        && (   s->width != s->avctx->width || s->height != s->avctx->height
+            || (h->sps.sar.num
+                && h->sps.sar.num != s->avctx->sample_aspect_ratio.num)
+            || (h->sps.sar.den
+                && h->sps.sar.den != s->avctx->sample_aspect_ratio.den))) {
         if(h != h0)
             return -1;   // width / height changed during parallelized decoding
         free_tables(h);