[MPlayer-users] Q: libavcodec, B-frames, mbd, v4mv

Michal Seliga michal.seliga at visicom.sk
Mon Aug 25 17:22:30 CEST 2003

> Date: Mon, 25 Aug 2003 16:16:54 +0300 (EEST)
> From: Tuukka Toivonen <tuukkat at ee.oulu.fi>
> To: mslama at email.cz
> Cc: mplayer-users at mplayerhq.hu
> Subject: Re: [MPlayer-users] Q: libavcodec, B-frames, mbd, v4mv
> Message-ID: <Pine.GSO.4.55.0308251610110.10178 at stekt37>
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> On Mon, 25 Aug 2003 mslama at email.cz wrote:

> >besides CVS log? B-frames are disabled by default. Any notes/suggestion
> >about enabling them? (ie. what is probable gain of using them?)

> Very little. I was recommended to use a single B-frame at maximum. Anyway
> the difference is so small that I wonder whether it's a libavcodec-specific
> problem or why the standards include B-frames anyway?

I disagree. In some cases b frames help a lot. mostly in lowmotion scenes. but they
have one big disatvantage - classic divx codec on windows will not play such files
correctly (you would have to use ffdshow codec, which is IMHO better anyway). and
sometimes (very noisy or low quality encoded source) it can make video bigger (with 
same quality) or uglier (with same size)

But I agree that single B-frame is usually enough... (more b-frames can make file shorter
but difference is not so big compared to difference between 0 and 1...)

What I usually do is that I encode video using all possibilities for b-frames (0-4) with fixed
quantizer and for final encoding I use settings which made the output file shortest.

(for short videos, for DVD I do something similar but only with some chapter)

(don't laugh, I prefer quality before encoding time ;-)

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