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Old 11-02-06, 04:50 PM   #1
sherbey
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Default XvMC and H.264 MPEG4 acceleration

Hi,
I understand that at present XvMC does not support H.264 acceleration, only MPEG2. This is a problem in europe where most HDTV channels are broadcast in H.264. Is there a proposal to add H.264 and MPEG4 decoding generally to XvMC in some future release of the nvidia driver, and if so when roughly will it happen?
Presumably it would be both iDCT and MC...

I was thinking of building a mythtv box to get BBC HD, using a 430/6150 chipset. A bit pointless if HDTV won't work or stutters

Also, the SKY + HD box uses HDCP I believe; if I can get the channels will I trip at the last hurdle by a non-HDCP DVI-D connector downsampling the video OR not displaying it?

Cheers
Mark
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Old 11-03-06, 07:29 AM   #2
zbiggy
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Default Re: XvMC and H.264 MPEG4 acceleration

XvMC supports MPEG-4.
+
Nvidia driver does not support MPEG-4.
+
Nvidia hardware since geforce6 supports MPEG-4.
=
Ask Nvidia to add MPEG-4 support to Linux driver. Via unichrome driver provides mpeg-4 acceleration in Linux (using XvMC) but it is said this driver has security holes and is quite buggy. I can not understand why Nvidia does not provide mpeg-4 support in Linux. Nvidia has already mpeg-4 acceleration in Windows so have know-how and code.
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Old 11-03-06, 07:51 AM   #3
sherbey
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Default Re: XvMC and H.264 MPEG4 acceleration

Indeed. Apologies for the ambiguity; what I meant was that the nvidia implementation of XvMC doesn't support MPEG4.

I'm not sure the XvMC API fully supports all the aspects of H.264 that can be accelerated by the GPU, but I guess thats another question.

What I am after is a statement from an nvidia representative as to whether MPEG4 acceleration (and specifically H.264) will be supported in an nvidia binary driver at some point or not. PureVideo does, so the silicon can support it.

Cheers,
Mark
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Old 11-03-06, 10:47 AM   #4
mooninite
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Default Re: XvMC and H.264 MPEG4 acceleration

It would be nice to see nVidia support MPEG-4 acceleration...

Let's create a mob thread everyone! *grin*
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Old 11-03-06, 07:45 PM   #5
zbiggy
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Default Re: XvMC and H.264 MPEG4 acceleration

XvMC API supports the following formats:
mpeg-1/mpeg-2/h263/mpeg-4 for iDCT and MotionCompensation levels of hardware acceleartion. There is unofficial extension for VIA chips to support more advanced VLD decoding level at hardware.
chroma formats: 4:2:0/4:2:2/4:4:4

Nvidia Linux driver supports MPEG-2 only at iDCT and MC levels of accelearation and chroma 4:2:0 since geforce4mx.

VIA advertises the Linux driver for unichrome decodes mpeg-1/mpeg-2/mpeg-4 at iDCT/MC/VLD levels of acceleration. One user of unichrome told me the h263 is really accelerated not mpeg-4.

Intel for its integrated chips offers mpeg-1/mpeg-2 acceleration at MC level. New G965 and GMA X3000 chips has iDCT support so probably new driver releases will allow iDCT on 3000 chips.

ATI hardware has iDCT/MC support but Linux driver can not use it. Only Xv is available without any hardware decoding.
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Old 11-04-06, 04:15 AM   #6
pe1chl
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Default Re: XvMC and H.264 MPEG4 acceleration

zbiggy: do you know how this XvMC accelleration really works?

I can use it with mplayer and it uses less CPU than software decoding, but there still seems to be some bottleneck. Someone said that the data is copied back and forth to the video card several times for each frame, and that this means the bus is heavily loaded eventhough the CPU isn't. Is that true?

I have an AGP 4x bus and playing 1080i HDTV video still is on the very edge of the system capability, causing more or less frequent frame drops.
At first, I had IDE disks on an extra controller in a PCI slot that happened to share the interrupt with the videocard. The performance was terrible when playing 1080i mpeg from those disks. It was sort of OK when playing from memory or other locations.
Now, I have moved all my video disks to a separate NFS server attached with gigabit ethernet, and it is a bit better but still not usable for relaxed viewing. I cannot stand watching a movie with semi-random stuttering occurring all the time.

I also have a dreambox and this has REAL hardware decoding. Even when the CPU is heavily loaded with something, and the GUI is barely responsive anymore, the video (and audio) continues without a glitch.
What I would like to see in my PC is a similar thing. I visualize this as a card where I can just pump mpeg (or h.264) data over some fast stream interface (probably DMA), and the card takes it from there without ANY real-time attention from the CPU.
The system would then only need to do the reading of data from the filesystem or other source and sending it to the card, which should be easy these days. And there can be a several megabyte buffer inbetween that bridges gaps where the system is paying attention to something else.

Is the XvMC API up to providing such a capability, and is it just a matter of waiting until Nvidia improves their driver so that it works correctly? Or is the whole XvMC thing operating at a lower level and can we never expect truely independent hardware decoding of video using methods like this?
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Old 11-04-06, 06:11 AM   #7
Linuxhippy
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Default Re: XvMC and H.264 MPEG4 acceleration

i personally don't care that much about video, however this is also a non-3d enhancement.
+ 1 wants this
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Old 11-04-06, 07:19 AM   #8
pgs
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Default Re: XvMC and H.264 MPEG4 acceleration

Quote:
Originally Posted by sherbey
Hi,
I understand that at present XvMC does not support H.264 acceleration, only MPEG2. This is a problem in europe where most HDTV channels are broadcast in H.264. Is there a proposal to add H.264 and MPEG4 decoding generally to

Mark
Could you please provide some references/links about the fact that "in europe most HDTV channels are broadcast in H.264"?
AFAIK HDTV is mpeg2 in Europe and there are only a couple (BBC is one) of channels which are experimenting with mpeg4/h264, but if you have some other info I would like to read something more.
Thanks.
pgs
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Old 11-04-06, 09:27 AM   #9
pzgren
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Default Re: XvMC and H.264 MPEG4 acceleration

Quote:
Originally Posted by pgs
Could you please provide some references/links about the fact that "in europe most HDTV channels are broadcast in H.264"?
AFAIK HDTV is mpeg2 in Europe and there are only a couple (BBC is one) of channels which are experimenting with mpeg4/h264, but if you have some other info I would like to read something more.
Thanks.
pgs
No, eg. all German HDTV channels are in the better mpeg4/h264 in DVB-S2 8PSK. BBC HD is using only DVB-S, but also mpeg4. Here is a Europe satellite list for only HDTV channels:

http://en.kingofsat.net/hdtv.php
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Old 11-04-06, 11:18 AM   #10
russofris
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Default Re: XvMC and H.264 MPEG4 acceleration

Hi there,

Nouveau currently has Xv & EXA working. Perhaps someone here would care to start working on the XvMC bits?

Thanx much,
Frank
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Old 11-05-06, 11:53 AM   #11
Gregoire.Favre
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Default Re: XvMC and H.264 MPEG4 acceleration

I own an 5950 Ultra 256Mb : there is no hope with it for mpeg4 acceleration ?
Thank.
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Old 11-05-06, 02:57 PM   #12
sherbey
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Default Re: XvMC and H.264 MPEG4 acceleration

The only HD european channels broadcast in MPEG2 are euro1080 as far as I was aware, and they are moving to MPEG4. I've only really been looking at channels I can get in the UK, and are in english though . All the channels available are here:-
http://www.lyngsat.com/hd/index.html

There is a list of PureVideo-enabled cards here:-
http://www.nvidia.com/page/purevideo_support.html
so it looks like your 5950 card won't work with any MPEG4 acceleration that nvidia decide to offer in XvMC at some point, given that nvidia don't support it for MPEG4 acceleration in windows.

Any chance that an nvidia representative could comment on MPEG4/H.264 acceleration in XvMC? Is it a proposal for a future driver or is it proposed to be an extra-cost add-on like purevideo for windows? Or is it never going to happen? Would be good to know.
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