[gst-devel] unable to play mpeg-4 file

[Wim Taymans]

On Mon, 2006-08-21 at 18:09 +0100, alberto colombo wrote:
> hello
> 
> I have a problem with gstreamer not being able to display mpeg files
> encoded with a particular capture cards. The files should be compliant
> and VLC plays them correctly. The whole story is actually a bit
> complicated, it's all written here: http://www.albx79.it/stuff/ 
Hi,

The two files (MPEG2-pub.avi and MPEG4-pub.avi) contain DIVX4 in avi.
The file has 230 frames but length as specified in the video stream
header is 0. The GStreamer AVI demuxer incorrectly assumes there is
nothing in the complete file because of that. The video has size of
720x576 and a pixel-aspect-ratio of 12/11. VLC plays it too tall,
MPlayer/xine both play it squashed. After fixing avidemux in GStreamer,
it plays correctly.

As for your question why this is so inconsistent why everybody uses
ffmpeg: no player (except ffplay) uses the ffmpeg demuxer but implement
their own ones as the ffmpeg demuxers tend to bit a bit buggy and less
featurefull than a well integrated demuxer. Lots of things that can go
wrong when demuxing like wrong timestamps (wrong sync), feed wrong data
to decoder (artifacts, crashes), wrong header parsing (wrong length,
stop prematurely)... Then also each framework has their way of dealing
with aspect ratios, each with different bugs, assumptions and
unimplemented features.

Wim  

> 
> can somebody have a look at the files (available for download on the
> webpage above) and tell me what's wrong with them (or with gstreamer?)
> 
> thankyou very much
> I'll try to be on #gstreamer as much as possible this week, possibly
> after 22.00GMT
> 
> take care
> alberto
-- 
Wim Taymans <wim at fluendo.com>