[MEncoder-users] Encodes for slow laptop

[Diogo Franco]

Em Dom, 2008-06-08 às 12:50 -0700, Stella-Terra Clemens escreveu:
> Hello,
> I want to thank you all ahead of time for being here and for working hard to
> create not only the best encoding tool I've ever used, but the great
> community support for said tool.  The Free Software movement is all about
> people power, and you all make it possible.  Thank you.
> So my question is this:  I got one of those neato XO Laptops from the One
> Laptop Per Child group and I've replaced the standard OS with Ubuntu, and
> I've been shocked to realize that such a slow laptop has the ability to play
> movies.  This is great, and I've decided to encode my sizeable DVD
> collection in such a way that they are all playable on the laptop.
> Unfortunately, I'm having a hard time getting really consistant results.
> Mostly my problem is that I can't keep audio sync.  I've done a number of
> different things on the player side, but my number one concern is the
> encoding.
> First off: what is the best codec to use on a slow system given DVD input
> for consistantly smooth playback and as good a picture quality as I can
> get?  I tried h264, but that turned out to be way too slow (or was I using
> it wrong?)  Mainly I've been trying to use XviD, but is there something else
> that would be better in this circumstance?
> My second question is: what are the factors that go in to fast video
> playback?  I've been messing a lot with the resolution and the bitrate, but
> that doesn't seem to have much effect?  Does the container matter much?  Are
> there encoder specific settings I should be looking into?
> Finally, I wanted to know about resolutions.  I've been reading conflicting
> things about resizing.  My instinct is to always crop as little as possible
> and then resize to mod16, but I've recently been reading that it's a bad
> idea to resize at all.
> BTW, the XO has the following stats:
> x86 processor at 433 MHz
> 256M DDR
> 1200x900 pixel display
> More information available here:
> http://wiki.laptop.org/go/Hardware_specification
> Thank you, everyone!
> Stella
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H.264 uses a lot of CPU-intensive (de)compression techniques that allows
it to have probably the best efficiency around today. Most cpu-time is
wasted on motion compensation (can't avoid it) and on H.264's CABAC,
that is a very efficient data compressor. You could try to encode with
nocabac to force x264 to use CAVLC. That will reduce compression
efficiency, degrading file quality and forcing you to use higher
bitrates, but will be easier on CPU. Also, disabling the loop filter on
the decoder side may help. It makes the picture look really nice, but
burns your CPU. You can do that on MPlayer with "-lavdopts
skiploopfilter=all". Also, consider using CoreAVC, that is a very fast
(proprietary) H.264 implementation.

If H.264 won't do, then I think your best bet is MPEG-4. Use
libavcodec's encoder and, if you're not using something lavc/ffdshow
based to play, set the fourcc to XVID (or DX50). I can't confirm if this
is true but I saw a lot of people saying that the ffmpeg encoder is
better than Xvid's.