[Libav-user] No pix_fmt auto conversion in avfilter?

[Andrey Utkin]

Could somebody explain why this code fails when FILTER_STRING is not
"scale", but just "fifo" or "copy"?
https://gist.github.com/1834778
The reason is that AVFrame out from filtergraph has 0x0 dimensions.
The point is that pixel format conversion must take place, but i don't
understand why avfilter doesn't sort it out automatically.
It is surprising because when i open "buffer" video source for
avfilter, i point in its params that input is in PIX_FMT_RGBA.
Could / should this be "fixed", so auto-coversion took place in such cases?
If so, i'd appreciate advices how to patch the libavfilter.

-- 
Andrey Utkin