[Ffmpeg-devel] decode_nal fails on a MP4 that works in QTP

[Derk-Jan Hartman]

On 07 sep 2005, at 17:16, Derk-Jan Hartman wrote:

> http://sidekick.student.utwente.nl/videolan/Mr&MrsSmith.mp4
> Sample created by Handbrake. plays in QTP. does not play in VLC.
>
> I got errors like this:
> [00000275] ffmpeg decoder warning: AVC: Consumed only 10 bytes  
> instead of 19
> (h264 at 0x3987400)

I just hacked libavcodec to skip the remainder if consumed < nalsize,  
and this at least make the file play.

DJ

>
> So i added some more debug:
> print of NAL unit
> [00000275] ffmpeg decoder warning: 4D  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning:  0  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: 28  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: 9E  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: 21  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning:  2  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: 82  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: F4  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: 20  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning:  0  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning:  0  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning:  0  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: 20  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning:  0  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning:  0  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning:  3  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: 30  (h264 at 0x3987400)
> [00000275] ffmpeg decoder warning: 80  (h264 at 0x3987400)
>
> ffmpeg bails decode_nal because this failed check:
> if(i>=length-1){ //no escaped 0
>         *dst_length= length;        *consumed= length+1; //+1 for  
> the header
>                     av_log(h->s.avctx, AV_LOG_ERROR, "unescaped 0\n");
>         return src;
> }
>
>
> Now the problem is that I don't know what NALs contain, what they  
> SHOULD look like, and how ffmpeg might be better able to handle  
> this if it is a problem in the NAL.
>
> Anyone can help me out beyond this point?
>
>
> DJ
>
> PPC G4 iBook + Mac OS X 10.4
>
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