[MPlayer-users] mencoder on slow CPU

DEBERT Jean-Louis jl.debert at rsd.com
Fri Feb 7 15:25:53 CET 2003

Jukka Tastula wrote:

>  On Friday 07 February 2003 11:25, DEBERT Jean-Louis wrote:
>  > Since the CPU is slow, you had better restrict yourself
>  > to "light" compression, i.e. mpeg1 or possibly mpeg2,
>  > but definitely not any of the mpeg4 variants, which are
>  > much more cpu-intensive. The resultant file will be
>  > somewaht bigger, but will be created faster ...
>  Since when did mpeg2 become "light"? Can you please tell me the encoder
>  are using? I remember encoding one ~45min clip for 8 hours on a 700MHz
>  and getting not-so-good quality from mpeg2enc. Sorry. Certainly not for
>  time encoding on a 466MHz celeron. Actually not even on this 1.666GHz
>  (which works just fine for real time full pal resolution mpeg4 encoding
>  mencoder).

Sorry, I had said _possibly_ mpeg2. Are you saying that at the same
mpeg4 is _less_ cpu intensive than mpeg2 ??? I could have sworn the contrary
Besides, as you noted later, it depends on the resolution chosen, and yes,
there is probably no way (even under windows) to do full PAL resolution
encoding with a 466Mhz celeron in real time (except possibly with
hardware such as in some TV capture boards, if the compression hw can be
managed under linux).

On the other hand, full PAL resolution may not be required: I frequently
view in mplayer some streamed videos encoded at 320x240, and even when
played full-screen (admittedly on a Matrox G400 which has a _very_ good
hardware scaler) the resulting image is nearly perfect, except when there
is a lot of motion.
I think that at 320x240 you have already divided your needed bandwidth
by 4 or more (simply in pixel count). It might then become bearable
even for a poor celeron-466. 

>  > Better yet, _if_ you have disk space, why not capture
>  > your TV programs without encoding (using mplayer -dumpstream)
>  > and encode later. This way is best, because mplayer -dumpstream
>  > doesn't consume much cpu, and for the later encoding pass
>  > you can use the best options, you have all the time you want.
>  You'll need some really nice hdd for this job, preferrably one that can
>  something like 20M/s write sustained. Otherwise forget it. 

Same remark as above, use a lower resolution and you save a lot of
both disk space and hdd bandwith neddedd

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