[MPlayer-users] Cutting avis with ss and endpos

[HR]

> [mailto:mplayer-users-bounces at mplayerhq.hu] On Behalf Of 
[...]
> I have found two possible solutions: either I encode in mjpeg which
> results in files twice as big with lower quality, or I raise 
> the number
> of keyframes.
> After looking through the encoding-tips.txt I tried the option:
> keyint=50
> This works, now I have only a two second tolerance, which is probably
> enough.
If you need a certain accuracy when cutting the file, the only realistic
option is as you already figured out - decreasing the I-frame interval.
Another option is to use a high keyint interval for overall quality,
then afterwards again encode the part where you want accuracy when
cutting, but with a (much) lower max keyint this time, followed by some
cutting and replacing. All other settings should ofcourse stay the same.
Scene change detection should place key frames at the exact same
locations every time, so this should work... in theory. Keyframes
inserted due to the max keyint value may ofcourse not be at the same
locations, so this would be a "scene replace" procedure.

> But there is also "Key frames are significantly larger than P or B
> frames, so the less key frames you have, better the overall movie will
> be."
> Huh?
> Shouldn't it be the other way, the more P-frames I have, the 
> better the
> output? After all, more memory is used which should result in better
> quality.
"Less I-frames" is the same as "more P-frames and/or B-frames". And both
give better quality, and less "cuttability". The default keyint in
mencoder (lavc/xvid) seems to be very sane, although I myself do use a
somewhat lower value for "cuttability".

HR