ATI HD4250, Catalyst 11.12 flawlessly supports DXVA beyond its specs (L5.1)

[would_like_to_know]

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To summarize, install the latest Catalyst drivers (11.9 or later), get the latest MPC, set DXVA to "skip all checks" in MPC, and enjoy flawless L5.1 playback on CPU challenged systems for many more files. The commercial decoders seem to be worse! Note that for something like 16 reframes DXVA is still very glitchy, but nowhere DXVA is officially declared as supported for so many reframes.

Some resources I used to get DXVA set up properly:
http://zachsaw.blogspot.com/2009/06/...-dxva-for.html
http://www.mediasmartserver.net/2011...-an-intel-gpu/

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I have an Asus 1215T netbook with RS880 chipset and HD4250 graphics (single core AMD K125 cpu at 1.7Ghz, Windows XP SP3). The way DXVA works in MPC is that it checks first if the compression level is formally supported. If it is, MPC proceeds to use DXVA acceleration. If it is not, then MPC reverts to the full CPU mode. So a lot of times L5.1 content will revert to CPU mode, and people with lots of cores will report that DXVA worked fine when in fact DXVA was not used at all. There are tons of confusing reports like that on the Internet.

For me CPU decoding at L5.1 did not work smoothly at all. For a while I tried to disable DXVA compatibility checks in MPC (set to "Skip all checks") in order to coerce DXVA to be used for L5.1 1080p videos. And when the video level exceeded what is formally supported, the video did play with DXVA and low CPU utilization, but looked glitchy with odd blocky artifacts here and there. What is interesting is that I see pretty much identical behavior for my hardware player Samsung C6500, where beyond certain video level it still plays the file, but add artifacts for viewing pleasure.

After I installed the latest Catalyst 11.12, I tried to play such a glitchy file on Asus and it actually looked just fine with DXVA beyond its formal limits, and CPU utilization remained low. The specs for the file are as follows : L5.1, 1920x816, 11 reframes, 24fps. If I enable DXVA level check, then MPC reverts to CPU decoding, with 100% cpu use and dropped frames. So what we have here is that DXVA works beyond what it reports as officially supported.

For a test, I went back to the older Catalyst drivers, and was able to pinpoint the disappearance of artifacts between 2 Catalyst versions. 11.6 has artifacts (driver version 8.861), while 11.9 (driver version 8.892) is flawless.

I also tried CoreAVC decoder. But since it does not enable DXVA when the file is beyond the official DXVA support level, CoreAVC reverted to CPU decoding and the performance was horrible.

Interestingly enough, Arcsoft decoder does seem to use DXVA at any level, but has artifacts for my L5.1 file even with the latest Catalyst drivers. So ATI driver fixes did not cure Arcsoft artifacts at all.

[Juce]

I have done some tests:



So it does not follow any particular level.

[Barlow]

Afaik it's a limitation in Ati's driver on Windows XP. On Windows 7 i've had no issues with L5.1 files. Now we need Hi10P support though

[would_like_to_know]

Originally Posted by Juce

I have done some tests:



So it does not follow any particular level.

Nice work! So the driver effect that I have observed is for real. Indeed, it does not follow any logic as related to computing resources, with the same number of ref frames at all levels. But at least 14 re-frames is not too bad for now.

I watched a few movies since then, and noticed some jerkiness which I think could be more related to the MPC's DirectShow video renderers and not the DXVA decoder itself. A movie at 1080p seemed to work perfect on a 1080p screen, but a couple of other 720p movies were a bit jerky on the same 1080p screen. Not sure what this is all about since the cpu use seemed fairly low in all cases. I tried several different DirectShow video options, and while the character of the jerkiness seemed to change, the effect never went away for those 720p files.

[Juce]

Windows 7 and HD 3400:

640 x 480 ... 1024 x 576 16 ref frames
1280 x 720 12
1920 x 1080 5

I don't know the exact model. GPU-Z just says "HD 3400 Series":