DxVA Profiles Support limitations in ATi 5xxx series UVD2 - AVS Forum
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post #1 of 55 Old 02-15-2010, 04:02 AM - Thread Starter
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Starting with UVD2 and VP3, both, AMD/ATi and nVIDIA feature full bitstream support for all Blu-Ray video formats, including MPEG-2. Question is how can a decoder take advantage of that? DXVAChecker reveals what drivers provide to access the hardware decoders under Windows operating systems.


Figure 1 - DXVAChecker - HD4550 UVD2

In case of ATi, there seems to be no standard interface to offload the whole MPEG-2 bitstream decoding to the UVD. DXVA decoders still use the iDCT profile which is executed within shaders. Entropy decoding and motion compensation are handled by the CPU. Power consumption would come down quite a bit if all stages were decoded within ATi's UVD fixed function unit.

nVIDIA ION and all GPU's with >= VP3 on the other hand provide 'ModeMPEG2_VLD' to DXVA decoders, see figure 2.


Figure 2 - DXVAChecker - ION with VP3



From above figures, we can see, there are NO DxVA profiles support (on UVD compared to nVidia VP3) for:

1. ModeMPEG2_VLD | Yes, you didn't see wrong, the ATi cards don't support BSP for MPEG2 SD and HD contents.

2. ModeVC1_IDCT

3. ModeWMV9_IDCT

4. ModeH264_VLD_FGP

5. X8R8G8B8 FourCC.




Does anyone really noticed the above DxVA profiles limitations even in ATi's latest 5xxx series cards in your HTPC??
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post #2 of 55 Old 02-15-2010, 09:39 PM - Thread Starter
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No one really cares about the MPEG2 DxVA profiles support limitations on even the latest ATI 5xxx series UVD2?

I compared 13Mbps H.264 and 20Mbps MPEG2 and found latter has better video quality. Not saying the world best Japan BSD (24Mbps MPEG2) in video quality.
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post #3 of 55 Old 02-15-2010, 09:52 PM - Thread Starter
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I tried some high bitrates (18Mbps and above) MPEG2 HD channels here, some channels even got 20% CPU occupation on my 4 core Intel CPU (DVBViewer, CyberLink PDVD9 w/ DxVA)!! Compared with nVidia 8400's 3% CPU on the same MPEG2 HD channels, this was really unacceptable!!

So MPEG2 full DxVA support is essential. This is just the driver limitation, hope ATI video driver team can work to have full MPEG2 DxVA supports!
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post #4 of 55 Old 02-15-2010, 09:52 PM
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What is FGT, film grain tech?
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post #5 of 55 Old 02-15-2010, 10:21 PM - Thread Starter
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Quote:
Originally Posted by kevinqian View Post

What is FGT, film grain tech?

That's correct.
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post #6 of 55 Old 02-15-2010, 10:25 PM
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Compared with nVidia 8600's 3% CPU on the same MPEG2 HD channels, this was really unacceptable!!

AFAIK 8600 doesn't feature full bitstream support for MPEG-2 either. This is only supported from VP3 onwards.
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post #7 of 55 Old 02-15-2010, 10:31 PM
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Quote:
Originally Posted by kevinqian View Post

What is FGT, film grain tech?

that's my question. what is it
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post #8 of 55 Old 02-15-2010, 10:38 PM
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The way I understand it, film grain is removed before compressing the movie which improves compressibility big time. This film grain is then compressed separately in an efficient way. If a decoder does not support FGT it can't reconstruct the film grain.

AFAIK no encoder takes advantage of that so far.
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post #9 of 55 Old 02-16-2010, 12:59 AM - Thread Starter
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Quote:
Originally Posted by CiNcH View Post

AFAIK 8600 doesn't feature full bitstream support for MPEG-2 either. This is only supported from VP3 onwards.

Sorry, it's a low profile nVidia 8400 suitable for HTPC years ago which was recommended by Tom's. Don't know if it uses VP3.
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post #10 of 55 Old 02-16-2010, 02:19 AM
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8400 has VP3 yes, see here.
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post #11 of 55 Old 02-17-2010, 10:53 PM
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All our DVB-T is in H.264 and AAC sound here in NZ, only MPEG2 I use is the odd Bluray and DVD. Our satellite system is MPEG2 though.
So doesn't really effect me, so haven't ever looked at CPU usage with MPEG2.
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post #12 of 55 Old 02-18-2010, 12:02 AM
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Lucky aussies and europeans get H264 content. ATSC is stuck in the 90s.

Mpeg2 decoding is really a nonissue as even an old P4 can do the job fine. What are you so concerned about?
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post #13 of 55 Old 02-18-2010, 04:43 AM - Thread Starter
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Quote:
Originally Posted by kevinqian View Post

Lucky aussies and europeans get H264 content. ATSC is stuck in the 90s.

Mpeg2 decoding is really a nonissue as even an old P4 can do the job fine. What are you so concerned about?

Our satellite and cable HD channels are all in MPEG2 which have the bitrates of 18Mbps and above, so it's meaningful here to get full MPEG2 DxVA profiles support.
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post #14 of 55 Old 02-18-2010, 05:17 AM
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Especially for high bitrate HD content, one will see quite a difference. It is not just about whether the CPU can handle it with ease or not. When using the DXVA iDCT profile for MPEG-2, the stages IQ, iDCT and MC are handled by shader and CPU ALU's, so even the stages that are supposed to be fully computed on the GPU by a dedicated processor are in fact only accelerated, so partially being offloaded to the shaders. A lot of calculations and also VLD to a full extent are computed by the CPU. Still both, shader and CPU ALU's, are general purpose nature, always requiring much more processing power to execute the same tasks compared to a dedicated hardware like the UVD.

When building a HTPC, one fights for every Watt to spare. Why not using the dedicated low power hardware if it is there but just lacking proper driver support?

Seems like VLD/bitstream-level decoding for MPEG-2 can be enabled via registry (see also DXVAChecker) for HD 4000 and 5000 series GPU's featuring UVD2 (key 'VForceUVDMPEG2VLD'). But it may not function correctly. So the way ATi deals with this issue is simply disabling the feature instead of debugging..
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post #15 of 55 Old 02-18-2010, 07:20 AM - Thread Starter
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Quote:
Originally Posted by CiNcH View Post

Seems like VLD/bitstream-level decoding for MPEG-2 can be enabled via registry (see also DXVAChecker) for HD 4000 and 5000 series GPU's featuring UVD2 (key 'VForceUVDMPEG2VLD'). But it may not function correctly.

Do you have an 4000 or 5000 card to test? How to check if the tweak works correctly or not?
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post #16 of 55 Old 02-18-2010, 07:42 AM
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No, I don't have one myself.
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post #17 of 55 Old 02-18-2010, 08:16 AM
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Quote:
Originally Posted by ter9999 View Post

Do you have an 4000 or 5000 card to test? How to check if the tweak works correctly or not?

I have a HD4550 and tested it yesterday (I read CiNcH's blog/comment on dvbviewer forum before).
I tested it with 10.1 & 10.2 drivers on Win7 x64.

After the Tweak DXVA-Checker showed me the ModeMPEG2_VLD profile but when playing back a file the system crashed with a blue screen.

When watching TV with DVBViewer, the system did not crash, but I only got sound and green picture.
Cyberlink properties showed that the codec uses a "BSP" profile.

When I deactivated ModeMPEG2_VLD, everything was fine,
Cyberlink properties showed an IDCT profile.


greetz,

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post #18 of 55 Old 02-18-2010, 04:38 PM
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COme to think of it, this could make for a good class-action lawsuit for false advertising. AMD are you listening?
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post #19 of 55 Old 02-18-2010, 05:17 PM - Thread Starter
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Quote:
Originally Posted by sw4y View Post

I have a HD4550 and tested it yesterday (I read CiNcH's blog/comment on dvbviewer forum before).
I tested it with 10.1 & 10.2 drivers on Win7 x64.

After the Tweak DXVA-Checker showed me the ModeMPEG2_VLD profile but when playing back a file the system crashed with a blue screen.

When watching TV with DVBViewer, the system did not crash, but I only got sound and green picture.
Cyberlink properties showed that the codec uses a "BSP" profile.

When I deactivated ModeMPEG2_VLD, everything was fine,
Cyberlink properties showed an IDCT profile.

Thanks for your testing. This was indeed a horrible result! Don't know if 5000 series card gets the same result for MPEG2 DxVA2 BSP support.

Since there is an entry in registry, I think this is only the driver limitation. ATi should be blamed for the lacking of a BASIC function in their UVD.
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post #20 of 55 Old 02-18-2010, 06:17 PM
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Same problem on the 5000. see picture:

http://public.bay.livefilestore.com/...xva-hd5770.png
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post #21 of 55 Old 02-18-2010, 07:04 PM - Thread Starter
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Quote:
Originally Posted by kevinqian View Post

Same problem on the 5000. see picture:

http://public.bay.livefilestore.com/...xva-hd5770.png

Yes, still lacking of ModeMPEG2_VLD on 5700 series. Have you tried if the trick works or not on this card?
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post #22 of 55 Old 02-18-2010, 08:14 PM
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I don't have the card myself. Just pulled that from someone's screenshot. I assume the same limitations apply.

I say let's sue the bastards!!!
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post #23 of 55 Old 02-18-2010, 11:17 PM
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I say let's sue the bastards!!!

I wouldn't go that far. But for several reasons I documented here, I currently wouldn't buy an ATi. All you hear from ATi is that the issues are known but won't be fixed any time soon. Us HTPC user will stay a minority and the 50 bucks we invest into a low power/performance GPU are not worth the effort. Sad but true.
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post #24 of 55 Old 02-18-2010, 11:49 PM
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Quote:
Originally Posted by CiNcH View Post

I wouldn't go that far. But for several reasons I documented here, I currently wouldn't buy an ATi. All you hear from ATi is that the issues are known but won't be fixed any time soon. Us HTPC user will stay a minority and the 50 bucks we invest into a low power/performance GPU are not worth the effort. Sad but true.

But see, none of those other issues are advertised as features to the end user. This Mpeg2 VLD is explicitly advertised on UVD2 cards, which they clearly failed to implement. This would be considered false advertising. Say I bought this card explicitly for that advertised feature, only to find out it's completely disabled, not just error prone, but completely disabled. That's cause for lawsuits.

All the other grievances against these cards are either regarding features not advertised, or advertised but not functioning properly.
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post #25 of 55 Old 02-19-2010, 03:11 AM - Thread Starter
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Quote:
Originally Posted by CiNcH View Post

I wouldn't go that far. But for several reasons I documented here, I currently wouldn't buy an ATi. All you hear from ATi is that the issues are known but won't be fixed any time soon. Us HTPC user will stay a minority and the 50 bucks we invest into a low power/performance GPU are not worth the effort. Sad but true.

Hi CiNcH, you finally plan to buy a nVidia card? Which card to you prefer for an HTPC? I want to upgrade my display card too recently.

ATi cards have plenty of AVIVO options to deal with, in contrary, nVidia cards don't have much, it just do the decoding/post-processing silently in the background.

Also, how does the ATi vector adaptive deinterlacing compared to nVidia's deinterlacing mode?
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post #26 of 55 Old 02-19-2010, 05:53 AM
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Hi CiNcH, you finally plan to buy a nVidia card? Which card to you prefer for an HTPC? I want to upgrade my display card too recently.

I am not buying anything at the moment.

Quote:


ATi cards have plenty of AVIVO options to deal with, in contrary, nVidia cards don't have much, it just do the decoding/post-processing silently in the background.

I have no clue about the quality of those video post-processors, but they are all executed in the DXVA context, so before resizing, which is not where I would put a sharpener for example. There is simply too little transparency concerning the order in which the post-processors are executed and what they really do or how they work. So I keep them disabled anyway. Quantity is not what you should base your decision on in this case.

Quote:


Also, how does the ATi vector adaptive deinterlacing compared to nVidia's deinterlacing mode?

Both have very good temporal deinterlacers.
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post #27 of 55 Old 02-22-2010, 06:57 AM - Thread Starter
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I tried today on my 4850 card to set ModeMPEG2_VLD to 1 in DXVA Checker, both MPEG2 HD and SD went GREEN. See following snapshot:




So ALL ATi cards (including the latest 5000 series) can't do bitstream-processing of MPEG2 which should be a very basic feature.
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post #28 of 55 Old 02-23-2010, 07:20 AM - Thread Starter
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Yes, really bad practice for ATi of the MPEG2 BSP support advertisement in UVD2!

ATi driver team should enable this feature in UVD2!!!
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post #29 of 55 Old 04-17-2010, 04:07 AM - Thread Starter
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The lacking of MPEG2 BSP support in DxVA is still not resolved in Catalyst 10.3!
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post #30 of 55 Old 04-17-2010, 08:46 AM
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Ok.. so, MPEG2-HD formats, which have minimal usage, aren't supported correctly on ATI. ATI does however, properly manage X264, which is more of what people have concern for at the moment (correct?) And CPU usage to manage MPEG2-HD doesn't top 16% on a Regor-250 (a sub $50 CPU) when combined with a 5450.

On the other hand, we can flip to Nvidia, which while properly supporting it, has no platform at all to pass DTS-MA/TrueHD DD Bitstream. And Nvidia's color space profile is still wrong (black crush) and it's overscan supports suck.

I've come to the conclusion that neither card gets it 100% correct. But for now, this issue as a concern is a minor one compared to a shoddy HDMI interpretation that Nvidia has. As it appears, this is something that could be addressed in a future driver, so it's not that it's impossible.

Whereas ever having bitstream HD audio come through an Nvidia card is a hardware impossibility.

I get the concern. I'm just not worried about my processor jumping from 4% to 16%.
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