[FFmpeg-devel] h264: dealing with "broken links"

Reinhard Nissl rnissl
Mon Nov 19 21:00:51 CET 2007


Jeff Downs schrieb:

>> 1. all unavailable reference frames must be allocated and guessed from
>>    available frames (just memcpy them from a random available frame would
>>    do for now)
> Actually, is this still a problem for H264?  Code at the bottom of 
> decode_ref_pic_list_reordering appears to be looking through the whole 
> reference list, filling empty spots with a copy of the current picture.  
> Obviously not the perfect solution, but it makes them non-NULL.

It seems to work, as I don't get any messages regarding missing
reference pictures here.

>> 2. drop unimportant frames (B frames / theres a priority field in the NAL
>>    header which could maybe be used)
> Yes. mpegvideo MPV_frame_start expects last_picture_ptr to be valid 
> prior to allocating for B pictures.  H264 doesn't guard this and that's 
> why people keep seeing the endless loop to eventual picture buffer 
> exhaustion (would assert if so enabled).

That's the problem I do see here.

Dipl.-Inform. (FH) Reinhard Nissl
mailto:rnissl at gmx.de

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