[FFmpeg-devel] [FFmpeg-cvslog] r16616 - in trunk/libavformat: avc.c avc.h flvenc.c matroskaenc.c movenc.c

[Aurelien Jacobs]

Baptiste Coudurier wrote:

> Baptiste Coudurier wrote:
> > Aurelien Jacobs wrote:
> >> Baptiste Coudurier wrote:
> >>
> >>> Hi guys,
> >>>
> >>> lucabe wrote:
> >>>> Author: lucabe
> >>>> Date: Thu Jan 15 15:03:07 2009
> >>>> New Revision: 16616
> >>>>
> >>>> Log:
> >>>> Do not reallocate AVPacket's data when muxing a packet
> >>>>
> >>> Argh, I just noticed a problem with the patch, this broke muxing if nal
> >>>  startcodes are not 4 bytes :(
> >>>
> >>> I think this must be reverted and the other approach must be used
> >>> (allocating a new buffer).
> >>>
> >>> I will implement this in flv and mov muxer, I don't know much about mkv
> >>> muxer.
> >> For now, I haven't checked the problem you are talking about, but if
> >> you send a patch with a different implementation for mov and flv, I
> >> will happily adapt it to mkv.
> > 
> > Basically, when bistream uses 3 bytes nal startcodes, output size will
> > differ from input size, and this is not considered (old size is written
> > in the packet header), so output size must be computed before actually
> > writing data in the packet.

BTW: do you have a h264 sample with such a 3 bytes nal startcodes ?
For now, the matroska muxer uses the following code to detect whether
it should do nal reformating or not:
  AV_RB32(codec->extradata) == 0x00000001
So I guess it simply won't detect the kind of bitstream you are talking
about. I would like to fix this, and a sample would help.

Aurel