[FFmpeg-cvslog] r12894 - in trunk/libavcodec: aac_ac3_parser.c aac_ac3_parser.h aac_parser.c ac3_parser.c

[Michael Niedermayer]

On Fri, Sep 19, 2008 at 06:20:30PM -0400, Justin Ruggles wrote:
> Janne Grunau wrote:
> > On Saturday 19 April 2008 03:50:41 michael wrote:
> >> Author: michael
> >> Date: Sat Apr 19 03:50:40 2008
> >> New Revision: 12894
> >>
> >> Log:
> >> Change aac and ac3 parsers to use ff_combine_frame().
> > 
> > this breaks parsing of some AC3 streams. For example 
> > ac3_parsing_errors_rev12894.mpg in incoming.
> > 
> > I'm not sure if this is the actual changeset which is to blame. It is 
> > the first which introduces
> > "frame sync error" and "incomplete frame" messages. But those are only 
> > at the start of the file while the beeps with current trunk are later 
> > in the file.
> > 
> > Playback of that sample is broken from 13579 til 13653. Revision 13654 
> > fixes playback but introduces nasty beeps after each frame sync error.
> > 
> > Janne
> 
> I am aware of the issue, and I'm pretty sure I know what's causing it,
> but I'm not quite sure how to fix it.  It seems to be occuring when the
> first bytes of a frame header are at the end of the buffer.  The next
> parser call then has the start of frame as negative, which doesn't seem
> to work well with ff_combine_frame().  There was a patch which fixed the
> error messages, but didn't fix the problem because the 2 frames end up
> being sent in the same packet.

Does the following fix it? [if not i need a testcase that fails with it]

@@ -51,7 +56,7 @@
             }else{
                 i-= s->header_size -1;
                 s->remaining_size = len;
-                if(!new_frame_start){
+                if(!new_frame_start || pc->index+i<=0){
                     s->remaining_size += i;
                     goto get_next;
                 }

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The worst form of inequality is to try to make unequal things equal.
-- Aristotle
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