[mythtv-users] MPEG2 Editing

[Henk Poley]

Op zondag 11 april 2004 00:56, schreef Brian May:
> >>>>> "Ed" == Ed Wildgoose <lists at wildgooses.com> writes:
>
> What is the difference between MPEG4 and MPEG2? So far I gather MPEG4
> is for low bit rates, I assume some compromises were made to allow for
> lower bit rates?

The rest I can not answer, I have once edited MPEG2 video in a simple 'cut off 
the ends' the way. But MPEG4 is quite (err, very) different from MPEG2.

MPEG4 video (which is a small part of MPEG4) makes much more use of vectors, 
basicly you record the vectors of all the pixels, so no more visual blocks 
that suddenly drop out, like with bitrotted MPEG2 streams. Note that it's not 
the end-all for error-fallback. Ever seen an MPEG4 video that missed some 
I-frame (try mplayers index-restore function on broken downloads), so the 
people on the next shot were talking with the previous image still 'skinned' 
over them?

The MPEG4 profiles (<-- mention that word) that are implemented by codecs like 
divx, xvid and MS MPEG4 only use the video part. The full MPEG4 standard can 
store 3D video, avatars, meta data about all the elements, etc. It also has 
some new audio codecs.

MPEG4 is definately not some 'tweaked' version of MPEG4. I guess the MPEGIF 
website is the source to look for information, though as always, standards 
are quite cumbersome and 'dry' to read (about):

http://www.m4if.org/

	Henk Poley <><