[Montellese]

I put together samples of six different files that don't work properly in XBMC.
They all work fine in mpc-hc.

http://www.multiupload.com/VEKPHNCY56

The artifacts should be very obvious, except for the 720p L3.1 sample which only has slight blocking.

Thanks for putting these together. I ran them all with MPC-HC and XBMC and here are the results:

MPC-HC: All files run smoothly without any noise or artefacts. All show "H.264 bitstream decoder, no FGT" for "DXVA2".

XBMC:
- 720p L3.1 2ref: No noise but some artefacts (not that bad)
- 720p L4.1 6ref: The whole screen consists of artefacts
- 720p L5.1 8ref: Don't know if this is noise or tiny artefacts all over the screen.
- 1080p L4.1 4ref: Lots of artefacts (but not the whole screen)
- 1080p L4.1 5ref 1: Random artefact groups (only at the beginning)
- 1080p L4.1 5ref 2: Lots of artefacts (but not the whole screen)

[0wing]

I have found the source of the problem!

All files encoded with cqm=2 will have artifacts. cqm=0 works just fine, if the other settings are within the limits of DXVA on UVD+ aka L4.1 specs.

[theccap10]

I tried 0wing's samples as well. (thanks for that 0wing)

I basically got the same results as Montellese and 0wing.

All files ran in MPC-HC fine.

In XBMC the first file ran fine. All the others had varying forms of pixelation. Ironically, the 1080p file with the 4.1 profile and 5 reference frames still had some pixelation but not as bad as the others.

@CrystalP
For the out-of-spec 1080p file i have. When I force DXVA in MPC I get really bad pixelation. Exactly the same as what I get in XBMC. Not sure where that leaves us....

[0wing]

I tried 0wing's samples as well. (thanks for that 0wing)

I basically got the same results as Montellese and 0wing.

All files ran in MPC-HC fine.

In XBMC the first file ran fine. All the others had varying forms of pixelation. Ironically, the 1080p file with the 4.1 profile and 5 reference frames still had some pixelation but not as bad as the others.

@CrystalP
For the out-of-spec 1080p file i have. When I force DXVA in MPC I get really bad pixelation. Exactly the same as what I get in XBMC. Not sure where that leaves us....

Are you sure the first file had no blocking? If you mean the 720p L3.1 file, look at their clothes.

[CrystalP]

Nice! For the ultimate confirmation on cqm, you can encode some samples yourself with x264 and see what happens.

A check on the cqm value would be good until ffmpeg fixes the problem. Don't know how though.
Does VLC with hw accel show similar problems on the same files? At least we'd know for sure the issue has to be pushed on the ffmpeg side of things.

Still, we can conclude that L4.1 is a hard limit for the ATI3xxx, as MPC-HC shows the same problems as xbmc when going beyond that.

In theory, L4.1 also has a bandwidth limitation. Don't know if that affects the ATI3xxx or if that can be detected before playback. That could be tested with a carefully crafted sample.

I'm preparing a patch to respect the L4.1 limit with UVD and UVD+, and to fall back to software decoding.

At this stage of Dharma, I can't add a GUI setting or a notification on screen when a file exceeds the limit. That will have to wait for Eden.

[0wing]

An update.

The problem seems to be if any kind of cqm is used or not. Without cqm dxva works fine. With cqm there's different degrees of artifacts/blocking.

I made a quick sample encode with and without any cqm. Might not be the best scene choice but it's clearly visible to the left.

I'm no x264 encoding expert so I couldn't figure out how to get cqm=2, but I managed to encode with cqm=1 and that also gave me artifacts on playback.

http://www.multiupload.com/MAMBA7IXCJ

@CrystalP

VLC GPU acceleration doesn't work for me at all, artifacts/blocking and horrible frame rate.

[theccap10]

Are you sure the first file had no blocking? If you mean the 720p L3.1 file, look at their clothes.

@0wing

I had another look at that first file (720p L3.1) and I can't see any pixelation. The quality is on par with MPC.

[CrystalP]

The L4.1 check is in trunk. It will be backported to Dharma.

The H264 streams will be checked to be <= L4.1 for a predefined list of cards (pretty much the ATI3xxxx family, except 3200 and 3300)

To override, integrate this bit in advancedsettings.xml:

Code:

<advancedsettings>
    <video>
        <checkdxvacompatibility>value</checkdxvacompatibility>
    </video>
</advancedsettings>

with value = false if you want to turn on DXVA no matter what
and value = true if your card is not in the autodetect list and it doesn't support > L4.1.

The encoder settings are not easy to get at, I haven't found a way so far to test for the cqm switch.

[theccap10]

Nice work CrystalP. From all the UVD/UVD+ owners many thanks.

[freddyemmer]

Hi Guys,

Im having the same kind of problems only my setup is a asus p5n9300 with a dual core celeron 3200 and the onboard nvidia 9300 card.

Im using windows 7 32 bit with dharma beta build 2. I have only these issues with movies in HD format (1080,720) not with HD series (720P). Could you please help me to?

[muzzakus]

Don't get your hopes up, my acer revo also has the artifacts with some files...very annoying. Only in windows mind you, 32 and 64. Ubuntu is fine. Doing some more experimenting now....

After much Googling and experimentation I’m not sure I am any the wiser with respect to this artefacts issue except to say that it's most definitely not an XBMC issue.

http://forums.amd.com/game/messageview.c...TMP=Linear

http://imouto.my/watching-h264-videos-using-dxva/

The above links offer some interesting reading on the issue of DXVA offloading with ATI cards but ultimately there is no solution in there.

I’ve been experimenting lately to work out which files fail and why. For my system (and I have a HD3650 not 3850 as stated in my earlier post) I noted that the MKV files that play with no issues are typically files with low Reference Frames.

In one of the links above, one of the posters in that forum makes the observation that it’s not the resolution or the number of reference frames but a combination of these. He came up with the formula –

Resolution x * Resolution y * Reference frames < 10000000

I have found that to be exactly the case with my own experimentation. If the media I am playing is under 10000000 it works without pixilation, if higher it pixilates (is that a word?) or shows artefacts all over the place.

From all my reading and googling I’m not sure if this is a hardware limitation of the card/UVD+ or a software driver issue but either way looks like an ATI issue.

I’ve spent 12 months building my HTPC and experimenting with GPU offloading etc. I deliberately used an older spec machine to try and get some use/value out of an old system I had lying around . Ironically I’ve ended up spending more money on the case, cooling and quiet technology than I have saved by using old technology and an ATI graphics card.

Suffice to say I’m giving up on ATI and their drivers.

Goodbye old HTPC……. Hello Acer Revo

[TheSwissKnife]

Becasue ubuntu (linux) is using vdpau not dxva. I have shuttle (NG-ION) and this produces artifacts with DXVA2 too, but hardly ever in normal play, only if doing other things, fast forwarding, at initial movie start, sometimes when an overlay is added, or at fps >60fps, or bitrate > 60Mbps ish

[vanvonno]

Re: DXVA for Intel GMA 4500.
VLC player is working on this,

see: http://forum.videolan.org/viewtopic.php?f=7&t=83328

[djbase]

xbmc dharma beta 2 with ATI 5570 and latest catalyst drivers 10.9 win 7 x64 no problems with picture corruption or artifacts ! + top notch picture quality ! (res : 1080p 24hz) with DXVA2 on !

[lapino]

Just installed my first HTPC with a ASROCK 880GM mobo, using onboard hdmi. When enabling DXVA2 I get a lot of artifacting. Is there a fix for this?