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

[Phil Oleynik]

belcampo wrote:
> Phil Rhodes wrote:
>>> stepping forward is rather simple, it is 'normal'play at 
>>> non-standard speed.
>>> Going back is difficult in the sense you have to calculate several
>>> frames plus/minus the differences to 'know' how that former frame has
>>> looked.
>>
>> Precisely.
>>
>> 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 ??
In a smooth video intervals are 100-300 frames.
(consider 720p, it costs 1.3MBytes for frame, 300 frames are huge bulk 
of memory)

Phil