[Ffmpeg-devel] detecting and decoding key frames in H264

[Enrique Estalayo]

Hi all,

i need to decode key frames from H264 video files. To achieve it, i 
generate FastForward files (containing only key frames), but when I try 
to open these FF files with the 'av_open_input_file' function i get an 
'unknown format' error. Nevertheless, when I decode the complete H264 
video, encapsulated in MPEG2-TS, I have no problems... but the logical 
decoding errors while processing B frames (that's why i need the key 
frames).

On the other hand, the generated FF video files are decoded correctly 
using the Elecard/MainConcept decoders, so I guess the problem is not 
within the format of these files.

So:

1.- How can i avoid the 'unknown format' error while applying the 
'av_open_input_file' function to the FF H264 video files?

or

2.- How can i read and/or decode just the key frames in H264 with FFMPEG?

Thanks in advance,
Enrique.