[FFmpeg-cvslog] Fix potential infinite discard loop.

[Reimar Döffinger]

ffmpeg | branch: master | Reimar Döffinger <Reimar.Doeffinger at gmx.de> | Sat Feb  4 15:27:34 2012 +0100| [d7b542ae294aaf818f2a00c5606e009cf931e77c] | committer: Reimar Döffinger

Fix potential infinite discard loop.

Fixes trac issue #438.
Seeking in that sample would cause ogg_read_timestamp to fail
because ogg_packet would go into a state where all packets
of stream 1 would be discarded until the end of the stream.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger at gmx.de>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d7b542ae294aaf818f2a00c5606e009cf931e77c
---

 libavformat/oggdec.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
index 3a1abc0..4280f8f 100644
--- a/libavformat/oggdec.c
+++ b/libavformat/oggdec.c
@@ -282,6 +282,9 @@ static int ogg_read_page(AVFormatContext *s, int *str)
 
     if (flags & OGG_FLAG_CONT || os->incomplete){
         if (!os->psize){
+            // If this is the very first segment we started
+            // playback in the middle of a continuation packet.
+            // Discard it since we missed the start of it.
             while (os->segp < os->nsegs){
                 int seg = os->segments[os->segp++];
                 os->pstart += seg;
@@ -368,7 +371,11 @@ static int ogg_packet(AVFormatContext *s, int *str, int *dstart, int *dsize,
 
         if (!complete && os->segp == os->nsegs){
             ogg->curidx = -1;
-            os->incomplete = 1;
+            // Do not set incomplete for empty packets.
+            // Together with the code in ogg_read_page
+            // that discards all continuation of empty packets
+            // we would get an infinite loop.
+            os->incomplete = !!os->psize;
         }
     }while (!complete);