[FFmpeg-devel] [PATCH] libavformat/mov.c : Avoid seek request with invalid seek offset ( 9223372036854775799 ) after EOS
"zhilizhao(赵志立)"
quinkblack at foxmail.com
Tue Apr 26 11:28:25 EEST 2022
> On Apr 22, 2022, at 4:37 PM, Malviya, Janpriya <Janpriya_Malviya at bose.com> wrote:
>
> Hello ffmpeg Dev team,
>
> While integrating FFmpeg for M4A , MP4 stream & facing issue that mov demuxer trying to request seek for invalid seek offset.
>
> Issue details:-
> - Modified doc/examples/demuxing_decoding.c example to support Custom IO call-back because we have our own mechanism to read data from source
> - In custom IO seek call back , we do not support “whence” values AVSEEK_SIZE & SEEK_END , used to find stream size ( returning -1 in both the cases ).
> - In attached screen shot , where we are observing seek with invalid seek offset and the seek requested after End of stream is detected
> - Seek offset value 9223372036854775799 always the same ( I think INT64_MAX – 8 , 8 is length Atom type & size field )
> - If we allow to return proper stream size in seek callback then this problem is not observed.
The real issue isn’t about invalid seek offset, but use invalid box
size/type due to EOF.
Add another check just after the eof check in while condition isn’t
efficient. I tried another method:
[1/3] avformat/mov: remove an always true condition
http://ffmpeg.org/pipermail/ffmpeg-devel/2022-April/295712.html
[2/3] reindent
[3/3] avformat/mov: fix use invalid box size/type due to eof
http://ffmpeg.org/pipermail/ffmpeg-devel/2022-April/295713.html
>
> Fix :
> In attached patch to verify EOS condition before going to parse atom data.
>
> Signed-off-by: Janpriya Malviya <Janpriya_Malviya at bose.com>
> ---
> libavformat/mov.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 6c847de..9704550 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -7556,6 +7556,10 @@ static int mov_read_default(MOVContext *c, AVIOContext *pb, MOVAtom atom)
> if (atom.size >= 8) {
> a.size = avio_rb32(pb);
> a.type = avio_rl32(pb);
> +
> + if(avio_feof(pb))
> + continue;
> +
> if (((a.type == MKTAG('f','r','e','e') && c->moov_retry) ||
> a.type == MKTAG('h','o','o','v')) &&
> a.size >= 8 &&
> --
> 2.7.4
>
> <issueImage.png><reproduce_issue.c>_______________________________________________
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