[FFmpeg-devel] Multiple frame dimensions in a single stream

[Ivo]

Hi,

I am working on a TXD demuxer and decoder 
(http://wiki.multimedia.cx/index.php?title=TXD) and I have stumbled upon a 
problem. Basically the demuxer and decoder work fine when all frames have 
the same width and height. But if the size changes, the output stays at the 
old size. e.g. [fronten2.txd is from GTA:SA and contains eight frames]

ffmpeg -i fronten2.txd %02d.ppm

All ppm images are 512x512, but 07.ppm should be 512x256. The upper half of 
the 512x512 image does contain the right contents though. When I do

ffplay fronten2.txd

I see the output window resize but it does not display the right contents. 
It then switches back to 512x512 for the eight frame, which displays 
correctly again.

I have RTFS but I can not figure out what I am doing wrong. Can anybody 
explain to me how I should handle mid-stream dimension changes? Preferably 
decoder driven, though I could change that if it should be really done in 
the demuxer.

Thanks in advance,
--Ivo