[MPlayer-DOCS] CVS: main/DOCS/man/en mplayer.1,1.1182,1.1183

Ivan Kalvachev ikalvachev at gmail.com
Mon Dec 26 12:54:53 CET 2005

2005/12/25, The Wanderer <inverseparadox at comcast.net>:
> On 12/24/2005 11:13 AM, Ivan Kalvachev CVS wrote:
> >  .B keyint=<0\-300>
> >  maximum interval between keyframes in frames (default: 250 or one
> > -keyframe every ten seconds in a 25fps movie).
> > -Keyframes are needed for seeking as seeking is only possible to a keyframe, but
> > +keyframe every ten seconds in a 25fps movie. This is recommended default for MPEG-4).
> This needs an article - "a recommended default" or "the recommended
> default" - unless you're going to rephrase further to something like
> "recommended as the default". Also, why are you mentioning "default"
> again immediately after having given it in the line immediately
> preceding?
> > +Most codecs require regular keyframes in order to limit the accumulation of mismatch error.
> I've never heard of "mismatch error" in the context of video encoding
> before, and on brief consideration of the term I haven't been able to
> figure out what it would mean. It may not be strictly necessary to
> explain it, since presumably the subject is gone over in places where
> people can find it easily enough online, but I thought I'd point the
> fact out.

I took this phrace from mpeg papers. Basically this is the error
caused by difference of decoding (IDCT) transformation on the encoder
and decoder. You may remember older XviD encoding getting greenish on
very long sequences, that was caused by libmpeg2 dct transformation..
( h264 is excluded from the most part because it uses integer exact

> > +Keyframes are also needed for seeking as seeking is only possible to a keyframe, but
> I'd rejigger the pauses here slightly - comma after the first "seeking",
> and change the existing comma to a hyphen.

Fix it as you please.

After hearing what Michael said, I think that returning the phrase
<132 would be mandatory. But with the addition that it must be <=132
of P-Frames. So if you use e.g. 1 b-frame u get double that (264).

I haven't looked at the encoder and i supposed that it was complaint
and enforces the rule at MB level. This may need to be fixed (at least
for vstrict ;)

Fix the text as you please.

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