[FFmpeg-devel] [PATCH] libx264: Add option to force IDR frames

[Yusuke Nakamura]

2015-08-19 0:20 GMT+09:00 Carl Eugen Hoyos <cehoyos at ag.or.at>:

> Hendrik Leppkes <h.leppkes <at> gmail.com> writes:
>
> > Whats the other reason for forcing a keyframe, ie.
> > why don't we always set IDR?
>
> I don't know if x264 supports it (and I wanted to ask)
> but h264 reference frames can be older than the last
> I-frame (but not older than the last IDR-frame).
> The I-frame is no recovery point in that case iiuc.
>
> Carl Eugen
>
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x264 can make I-picture as a random accessible point when using Open-GOP
feature (recovery_frame_cnt == 0). I don't know there is guarantee that AVC
decoder always discards undecodable leading pictures in output order when
seeking to such I-picture, but at least recent ISO Base Media has a feature
for handling this situation correctly.