[MPlayer-DOCS] [PATCH] Choosing the video codec

Guillaume Poirier docmaintainerwannabe at laposte.net
Mon Dec 26 16:44:00 CET 2005


Reimar Döffinger wrote:
> Hi,
> On Mon, Dec 26, 2005 at 03:30:22PM +0100, Guillaume Poirier wrote:
>>  Therefore, you can't be wrong choosing MPEG-4 AVC codecs like
>>  <systemitem class="library">x264</systemitem> instead of MPEG-4 codecs
>>  such as <systemitem class="library">libavcodec</systemitem> or
>>  <systemitem class="library">XviD</systemitem>
> That is a very bold statement. Beyond the reasons you mentioned, the CPU
> usage can be a very good reason to use older codecs (CPU usage on
> decoding, it doesn't matter as much for encoding).
> I would expect that I'm not the only one who still occasionally uses an
> old P-II class PC.

Good point!!! I tend to forget about those "details" as I tend to run
only beefy PCs that makes me believe that I'm a real macho man ;-P

Yes, there are still some ppl running exotic plateforms like Sparc, PPC,
ARM, and dalias's K6 :P

>>  Please refer to the technical specs of your player for more informations.
> (if you can find any *evil grin*)
> But really, unless things changed a lot these "technical specs" are
> useless in most cases. Like the "usage manual" for my notebook, it
> didn't get much farther than saying "you should not take it with you
> when you take a bath". Seriously, it said something like that!!

You're right about that. My own standalone players doesn't say much
about supported ASP features. I guess it would be a good idea to give a
link to one of those website which has infos about those players. I used
to have the link, but I guess I'm gonna have to google again to find it.

Does someone know a good site that has those infos.

>>  You may also consider choosing a codec that can do multi-threaded
>>  processing.
>>  <systemitem class="library">libavcodec</systemitem> does allow that,
>>  but at the price of picture quality for some low speed gains.
>>  <systemitem class="library">XviD</systemitem> has some experimental
>>  patches available to boost encoding speed by about 50-60% in typical
>>  cases with low picture degradation.
>>  <systemitem class="library">x264</systemitem> also allows multi-threaded
>>  encoding, which currently speeds-up encoding by 30-35% while lowering
>>  PSNR by about 0.05dB.
> Are you sure these values aren't overly optimistic?

as far as x264 is concerned, this is based on some benches I collected
(some made by Tuukka's and some made by me on a dual code P4). This may
be a bit optimisitic, as I did not test all combinations of options.
Maybe it would be wiser to talk about a 15-35% speed-up just to be sure
no one complains.

As far as XviD is concerned, I just took the figures given by SysKin:
http://forum.doom9.org/showthread.php?t=104257 but I have not made tests
mayself. Since the patch is based on x264's "slice encoding" code, I
just assumed that the picture quality was small.


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