Bruno Kleinert <fuddl@???> writes:
> Am Samstag, den 15.11.2008, 13:09 +0100 schrieb Ralph Lindner:
>> Zwar wurde auf meine Rückfrage was denn mit H.264 (mpeg4) HDTV wäre
>> erwidert, dass ohne das ja wohl heutzutage gar nichts mehr geht, mir ist
>> aber nach wie vor unklar, ob von dem System erwartet wird, dass es live
>> MPEG4-Streams in Echtzeit dekodieren können soll oder ob dies nur für
>> mpeg2 erwartet wird. Bin kein Informatiker, aber allein aus der zu
>> verarbeitenden Datenmenge vermute ich, dass eine MPEG4-Dekodierung
>> ein Vielfaches der Rechenleistung einer MPEG2-Dekodierung erfordert.
> kann i.d.r. die grafikkarte, AFAIK auch via chrome und die
> "integrierten" dinger. treiberunterstuetzung gibts unter x.org AFAIK
> noch nicht! ohne rauf- oder runterskalieren (!!!) sollte full HD
> allerdings kein unloesbares problem sein.
Ich hab da mal in #ffmpeg-deven diesbezgl nachgefragt. Hier ein irc log:
10:07 <+siretart> janneg: err, does openchrome now support xvmc or not?
their website seems to claim they do not, so I'm a bit confused now
13:40 < Compn> siretart : there is a patch for unichrome to support xvmc
(for mplayer), but i think it was rejected >>
http://lists.mplayerhq.hu/pipermail/mplayer-dev-eng/2004-September/029733.html
13:41 <+siretart> Compn: what graphics card would you recommend to buy
for using hardware accelerated mpeg2 decoding? AFAIUI only s3 chrome and
intel chips and drivers support them, is that right?
13:42 < Compn> you only want mpeg2 accel?
13:43 < Compn> actually i have no idea, talk to xvmc guys
13:45 <@iive> lol
13:46 <@iive> intel doesn't provide even idct level, without it xvmc is
slower than mmx
13:48 <+siretart> Compn: what else could one want other to mpeg2 accel?
I'd like to build cheap, quiet and low-end multimedia box, and am
considering what graphic card to buy. Now I've read that xvmc is what
you need if you want to have hw mpeg acceleration
13:49 <+siretart> or is hw acceleration anyway something that actually
no one needs these days?
13:49 <+siretart> iive: that's interesting. so you indicate that xvmc is
crap anyways?
13:50 <@merbanan> siretart: no need for hw acceleration at SD
resolutions
13:51 <+siretart> merbanan: ok. and what if I wanted to do playback HD
material as well?
13:51 <+siretart> merbanan: and does this even stand for amd geodes @900
mhz?
13:51 < Compn> why would you build a box with 900mhz cpu ?
13:52 <+siretart> because these geodes require only about 7.5W power.
13:53 <@merbanan> siretart: I have a geode myself, you would need a gfx
card to offload decoding on it
13:53 <@DonDiego> mru: you around?
13:53 <@merbanan> but then there is no solution for that so it's not
possible anyway
13:54 <+siretart> merbanan: okay. what geode do you have? are you happy
with them or are they too slow for SD and HD material?
13:54 <@merbanan> siretart: what you could do is hope for a solution to
arrive in the future
13:54 <@merbanan> my geode is a fit-pc so I don't play any video on it
13:54 < Compn> siretart : is electricity expensive where you live? :P
13:55 <@merbanan> and geodes have their own graphics card that isn't too
fast either
13:55 < Compn> 900mhz is fast enough to play most sd divx and 640:480
h264 (barely)
13:55 < Compn> from my tests with amd duron 900
13:59 <+siretart> okay, thanks. that's helpful
14:00 <+siretart> Compn: it's not the electricity that's expensive, it
is the required cooling.
14:02 <@iive> siretart: xvmc idct level is supported by nvidia and it
could be up to 3 times faster than software
14:03 <@iive> the real problem is h264 decoding
14:05 <+siretart> so it helps only with dvd playback, but not with
HD/divx material?
14:06 <@iive> unfortunately
14:07 <+siretart> is that a problem with nvidia or with xvmc in general?
14:07 <@iive> xvmc in general
14:08 <@iive> there was attempt to extend it to support mpeg-4-2,
vc1/wmv9 and h264
14:08 <@iive> but it haven't got any major support, mainly by driver
level.
14:10 <+siretart> thanks, that's helpful!
14:11 < Compn> current xvmc is mpeg2 only
14:11 < Compn> the new things from ati/nvidia are for vc1/h264
14:13 <@iive> i think that the things ati and nvidia release now
relataed to vc1/h264 decoding are not under common standard. so each
vendor goes in its own way
14:14 < Compn> correct
14:14 < Compn> also i forgot about via has their own , and probably
intel
14:26 <@reynaldo> mornings
14:31 <@iive> via bought s3 and unichrome
Also zusammengefasst:
- Die g3 geodes sind aus dem rennen, die sind einfach viel zu langsam.
- Hardwaresupport fuer MPEG2 existiert, die schnittstelle dazu heisst
xvmc
- xvmc sieht nur mpeg2 vor, mpeg4 kann das ding (noch) nicht
- die treiberunterstuetzung scheint mir bestenfalls unklar zu sein
- die generelle empfehlung ist besser Prozessoren mit vernuenftigem SSE
zu nehmen und dass dan von ffmpeg rechnen zu lassen.
Allgemein schtin mir damit v.a. der Intel Atom hervorzustechen, der ja
laut [1] bis hin zu sse3 kann.
Alternative koennte der via C7 prozessor sein, wenn man ihn halbwegs
vernuenftig bekommt. In jedemfall muss man da nochmal genau hinschauen,
welcher grafikchip dann auf dem jeweiligem board ist. Bei einer Intel
Atom Loesung ist man grundsaetzlich auf einen intel-chip festgelegt, der
mit sicherheit nicht die schlechteste wahl ist (intel kann xvmc!)
[1]
http://de.wikipedia.org/wiki/Intel_Atom
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