[MPlayer-users] how to "step backforward" ?

[Oliver Seitz]

>> However, "several frames" can actually be many tens or of frames, maybe
>> a hundred frames in some edge circumstances, and with intensive codecs
>> that's a very big job.
> Do you know any, where I-Frames/Key-frames are more then 12 (PAL) or 15
> (NTSC) between. Where are larger GOP-sizes used ??

Keyframes at a certain distance like 12 or 15 frames is only required on
DVD. If you encode a video to, say, MPEG4, you could tweak the encoder to
use one keyframe and encode the rest of the whole movie in deltaframes.
Smart encoder settings produce a keyframe not at a certain distance from
the last one but when there's a lot of change in the picture, like a cut
to another scene.

So it can easily happen that there are 100 or more deltaframes before the
next keyframe. But I think there would not be need for support for
delta-frame-only-files as they're quite very lots of unusual. And unusable
anyway.