[FFmpeg-devel] [PATCH 2/3] lavf/aiffdec: don't stop parsing after SSND chunk

[Matthieu Bouron]

On Sun, Jul 01, 2012 at 11:03:29PM +0200, Michael Niedermayer wrote:
> On Sun, Jul 01, 2012 at 10:37:24PM +0200, Matthieu Bouron wrote:
> > On Sun, Jul 01, 2012 at 08:59:04PM +0200, Michael Niedermayer wrote:
> > > On Sun, Jul 01, 2012 at 08:10:45PM +0200, Matthieu Bouron wrote:
> > > > On Sun, Jul 01, 2012 at 04:18:58PM +0200, Michael Niedermayer wrote:
> > > > > On Sun, Jul 01, 2012 at 11:16:42AM +0200, Matthieu Bouron wrote:
> > > > > > Some file has ID3 chunk placed after SSND.
> > > > > > ---
> > > > > >  libavformat/aiffdec.c | 2 --
> > > > > >  1 file changed, 2 deletions(-)
> > > > > > 
> > > > > > diff --git a/libavformat/aiffdec.c b/libavformat/aiffdec.c
> > > > > > index 4083316..9764f82 100644
> > > > > > --- a/libavformat/aiffdec.c
> > > > > > +++ b/libavformat/aiffdec.c
> > > > > > @@ -251,8 +251,6 @@ static int aiff_read_header(AVFormatContext *s)
> > > > > >              offset = avio_rb32(pb);      /* Offset of sound data */
> > > > > >              avio_rb32(pb);               /* BlockSize... don't care */
> > > > > >              offset += avio_tell(pb);    /* Compute absolute data offset */
> > > > > > -            if (st->codec->block_align)    /* Assume COMM already parsed */
> > > > > > -                goto got_sound;
> > > > > >              if (!pb->seekable) {
> > > > > >                  av_log(s, AV_LOG_ERROR, "file is not seekable\n");
> > > > > >                  return -1;
> > > > > 
> > > > > this will probably cause the whole file to be read in
> > > > > aiff_read_header() in some cases
> > > > > 
> > > > Yes, this will cause ffmpeg to seek at the start of every chunks.
> > > > This is required for some file (for example aiff files purchased from
> > > > beatport.com) which has their ID3 chunk after the SSND chunk.
> > > > 
> > > > Maybe a better solution would be to add an option which tell the demuxer to
> > > > look for other chunks after SSND ?
> > > 
> > > where is the id3 chunk exactly in relation to the audio data and
> > > other chunks as well as offset ?
> > > 
> > 
> > In my case, the ID3 chunk is placed after the entire SSND chunk (including
> > audio data). Anyway i didn't find any documentations which specify that
> > the ID3 chunk should be before or after the SSND chunk (or another type of
> > chunk).
> 
> hmm, well thats a unfortunate layout.
> at least a check shoudl be added if the underlaying protocol is
> seekable, because it not we cannot move to the end of the ssnd
> chunk because we would never be able to seek back and play anything
> (unless it all fits in our small buffer)
> 

I updated the patch to seek for the ID3 chunk only if the stream is
seekable.

Best regards,
Matthieu

[...]
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>From 544163deddfe2fa7b28e49e8344e83bc17143d78 Mon Sep 17 00:00:00 2001
From: Matthieu Bouron <matthieu.bouron at gmail.com>
Date: Sat, 30 Jun 2012 17:53:38 +0200
Subject: [PATCH] lavf/aiffdec: don't stop parsing after SSND chunk

Some file has ID3 chunk placed after SSND.
---
 libavformat/aiffdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/aiffdec.c b/libavformat/aiffdec.c
index 2c2b693..56338c0 100644
--- a/libavformat/aiffdec.c
+++ b/libavformat/aiffdec.c
@@ -259,7 +259,7 @@ static int aiff_read_header(AVFormatContext *s)
             offset = avio_rb32(pb);      /* Offset of sound data */
             avio_rb32(pb);               /* BlockSize... don't care */
             offset += avio_tell(pb);    /* Compute absolute data offset */
-            if (st->codec->block_align)    /* Assume COMM already parsed */
+            if (st->codec->block_align && !pb->seekable)    /* Assume COMM already parsed */
                 goto got_sound;
             if (!pb->seekable) {
                 av_log(s, AV_LOG_ERROR, "file is not seekable\n");
-- 
1.7.12.4