ffdshow's DXVA video decoder problem

[RazvanuZu]

Hi guys,

I'm using Avisynth v2.5.8 (official build), AvsP v2.0.2, GraphStudio and the latest build of ffdshow tryouts (2012-04-09).

This is the graph made by me:
http://thumbnails70.imagebam.com/19511/a656a9195109546.gif (http://www.imagebam.com/image/a656a9195109546)

The problem is that when I try to open this graph in AvsP I get this error:
http://thumbnails59.imagebam.com/19511/d1bbe3195109551.gif (http://www.imagebam.com/image/d1bbe3195109551)

I am sure this decoder doesn't start when I open the graph in AvsP because I can't see its icon in the notifications area.

What can I do in this case?
Thank you very much!

PS: http://thumbnails6.imagebam.com/19512/3bcd18195111468.gif (http://www.imagebam.com/image/3bcd18195111468)

[clsid]

You can't use a native DXVA decoder with AviSynth.

[RazvanuZu]

Oh, I didn't know this... In fact this was the first time I tried to use this decoder (DXVA)...

So there's nothing to do about this? I really want to use a DXVA decoder from now on, but I don't know what should I do in order to get it working...

Thanks! :)

[Guest]

If you are looking for GPU decoding and not necessarily DXVA decoding, then there are GPU-enabled Avisynth source filters, such as DGDecNV.

[RazvanuZu]

I'm looking for DXVA decoding. :)
I can't do anything about DXVA decoding with ffdshow tryouts, can I?

By the way, are there any quality differences between CPU decoding, DXVA decoding and GPU decoding?

[Andouille]

By the way, are there any quality differences between CPU decoding, DXVA decoding and GPU decoding?
Nope. All H.264 decoders output the same thing. If not, it's broken.
The only différence is the speed.

[RazvanuZu]

After some research I found that I need a video renderer and because of this I have switched to CoreAVC 3.0.1.

Now I have a problem with CoreAVC: when I try to use DXVA decoding I get this error -> http://thumbnails25.imagebam.com/19603/d69b10196023898.gif (http://www.imagebam.com/image/d69b10196023898)

If I select CUDA decoding or CPU-only decoding, this error doesn't appear, but MeGUI crashes after 1-2 minutes of work.

Please help me to get this DXVA decoder (@CoreAVC) or ffdshow's DXVA decoder working.

Thanks in advance!

[vivan]

Omg.
Please help me to get this DXVA decoder (@CoreAVC) or ffdshow's DXVA decoder working.
You can't use a native DXVA decoder with AviSynth.

Try LAV decoder with CUVID or DXVA-Copyback.

[RazvanuZu]

Thanks, vivan! Everything's working fine now.

[Music Fan]

Does it mean there is a way to use ATI's GPU in Avisynth ?

[detmek]

Yes, with DirectShowSoruce() or DSS2() (if you have Haali Splitter) and LAV Video decoder set to DXVA-Copyback.

[Music Fan]

Great, I believed it was only possible for Nvidia cards, not ATI's :)
I didn't know LAV.
Do we need to set anything in ffdshow and GraphStudio as explained in the first post, or just LAV is enough ?

[detmek]

If you have multiple H.264 decoders you have to make sure that LAV Video decoder is preferred decoder, that it has highest priority. Other then that, no. LAV is all you need.

[Music Fan]

Thanks, I will test it. ;)

[Music Fan]

Tested ; seems to work but the CPU works as much as with FFVideoSource() while it should use less CPU if GPU is used (I chose well DXVA-Copyback in LAV's options).:confused:
Actually the CPU works even a little bit more with DirectShowSource() and LAV (1 or 2 %) than with FFVideoSource().
I also verified with AVSMeter, same result.
Everything was disabled in ffdshow and the command DirectShowSource() didn't work before to install LAV, so LAV was clearly used thus I don't understand this result.:confused:

[detmek]

I just tried with Nvidia 9500GT and CPU usage is 0-1% with DXVA Copyback. Are you sure that LAV Video decoder is used and that it uses UVD chip? Download and start GPU-Z to check GPU and UVD usage. Also, open LAV decoder during test and see if it uses DXVA-Copyback or fails to avcodec.

[Music Fan]

Are you sure that LAV Video decoder is used and that it uses UVD chip?
I don't know.
My card is an Asus EAH5450 (clone of ATI HD 5450).
The DXVA works with MPC-HC (when I choose system default in output, directshowvideo), the CPU usage is 0-1% with h264 HD files.

Download and start GPU-Z to check GPU and UVD usage.
I downloaded it but as the CPU usage is around 20 % when I open my script in Virtual Dub, I guess the GPU is not used.

Also, open LAV decoder during test and see if it uses DXVA-Copyback or fails to avcodec.
I see "inactive".

But as I said above, my script couldn't be opened in Virtual Dub before to install LAV, so I guess LAV brought something because now my script is opened, while ffdshow is not used.
Even when I choose none instead of DXVA as video decoder in LAV, I see the video in Virtual Dub, so I don't understand how h264 is decoded.:confused:
My script is very simple, one line ;
directshowsource("H:\my video.mp4", audio=false)
also tested with a TS, both including h264, same result (CPU around 20 %).

Thanks for your help ;)

[detmek]

What OS do you have? LAV Video needs Windows 7/8 or at least Windows Vista. It only supports DXVA2.
If you open LAV Video decoder during script playback you can see what mode is used by LAV video.
https://dl.dropboxusercontent.com/u/19804113/Forumi/Slike/Doom9/DXVA%20Copyback%20active.png
If you see dxva2cb that DXVA-Copyback is used. If you see avcodec that LAV Video decoder falls back to software decoding.

[Music Fan]

What OS do you have? LAV Video needs Windows 7/8 or at least Windows Vista. It only supports DXVA2.
I have XP, I didn't know LAV was not good for XP. So I won't be able to use my ATI's GPU with Avisynth :( Unless LAV becomes XP compatible in the future (or unless ffdshow release a similar function).

If you see dxva2cb that DXVA-Copyback is used. If you see avcodec that LAV Video decoder falls back to software decoding.
I see "inactive". But as it concerns hardware decoder and as my video is decoded since I installed LAV, I guess that a software h264 LAV's filter is used, but not DXVA.
It would mean that LAV partially works also on XP.

[detmek]

AFAIK, nev does not plan to add support for DXVA1 decoding as official support for Windows XP ends in spring 2014.
So, your only options for hardware accelerated video decoding while using Avisynth are:
- buy Nvidia card and use CoreAVC with CUDA or
- upgrade OS to Windows 7 or Windows 8 and use LAV Video decoder in Copyback mod.

[Music Fan]

That's what I feared.:(
For DXVA in avisynth with a Nvidia card, shouldn't we use DGDecNV ?

[Asmodian]

Well I would suggest DGDecNV for gpu decoding on an Nvidia card but it would CUDA decoding, not DXVA.

I would bet a bit of money Nev will not implement anything for DXVA on XP or anything special for XP.. XP really is too old at this point (typing on an XP machine at work atm :( ).

[Music Fan]

It's old but still used a lot. Is it so hard to code for XP compared to Win7 ?
I hope ffdshow's team will do something in the kind of LAV DXVA copyback for XP.

What's the difference between decoding by CUDA and DXVA ?

[Guest]

Strictly speaking, it is CUVID, not CUDA, that performs the decoding for DGDecNV. CUVID is an API to the PureVideo engine.

[clsid]

CUVID works on XP.

Don't expect any improvements to ffdshow. Its project has been pretty much dead for more than a year.

[Music Fan]

Didn't know that, bad news.:(

CUVID works on XP
Ok but I need DXVA copyback for my ATI.

[clsid]

Copy-back is a feature of DXVA2, which requires Vista or above. It is not a limitation that is specific to the implementation in LAV.

[Music Fan]

Ok, so there is no hope for my configuration.:o

[Music Fan]

Hi,
is it still impossible to use DXVA decoding with Avisynth on Windows XP ?
As I said above a few months ago, I'd like to use my ATI's GPU with avisynth, which can be done with LAV but not on XP. And as clsid said, Copy-back is a feature of DXVA2, which requires Vista or above.
Thus I wonder if another way than copyback to use DXVA decoding with Avisynth exists or would be technically possible.

[nevcairiel]

DXVA1, which is used on Windows XP, is extremely limited. You won't be able to use it with AviSynth. You should switch to a newer OS if thats a requirement for you.

[Music Fan]

Ok, but I'd like to understand why MPC-HC (and maybe other players) can use DXVA on XP and Avisynth can't.:confused:
Is it because players do real time and Avisynth needs a kind of buffer memory (to store decoded frames) to allow slower than real time rendering, which wouldn't be possible with DXVA1 ?

[nevcairiel]

All you can do with DXVA1 is decode the video and then immediately show it on the screen (for playback). AviSynth needs to process the image to do its job, thats just not possible with DXVA1.
You don't need to fully understand it to accept that its impossible.

[Music Fan]

I understand, you answered my question.;) I guess that's what is called copy-back and that it's impossible with DXVA1.
CUDA looks different on that point because it can be used with Avisynth on XP, thanks to DGDecNV.

[Music Fan]

Hi,
I do have Windows 7 64 now but I still can't make LAV work with Avisynth ;
Yes, with DirectShowSource() or DSS2() (if you have Haali Splitter) and LAV Video decoder set to DXVA-Copyback.
I don't have Haali Splitter, is it also needed for DirectShowSource() (which I tried but DXVA-Copyback stays inactive) or only for DSS2() ?
I got picture (I opened my script in Virtual Dub) but as I see "inactive" below DXVA-Copyback in LAV's video decoder window, I guess the video is decoded by another filter.

[clsid]

You must access the settings of LAV by clicking on its tray icon to see the correct decoder state. Clicking on the Start menu shortcut loads another instance, which shows <inactive> because that instance of the filter is in fact not active!

[Music Fan]

I don't see its tray icon :confused:
But I believe LAV's copyback is not used because my CPU is around 45 % when I play this script while it's only around 3% when I play the TS file (the same than the one in my script) in MPC-HC (which use GPU).

[clsid]

Win7DSFilterTweaker can help you set LAV Video as preferred decoder.

[Music Fan]

Thanks, I will try this.

[Music Fan]

It works now when I play an Avisynth script opened in Virtual Dub (I see active for dxva2cb when I click on LAV's tray icon), but the CPU usage for a 1080p24 h264 video is around 20 %, which is quiet high for DXVA.
With MPC-HC 32 bit (installed on Win 7 pro 64) set also on LAV DXVA copyback playing the same video (without Avisynth), CPU usage is around 13 %.
I'm astonished by this difference because my script is very simple, one line (it was just for the test) ;
directshowsource(F:\my video.mp4")
I guess it means Avisynth needs more resources than MPC-HC because the decoder is exactly the same.
With Microsoft decoder instead of LAV's (chosen with Win7DSFilterTweaker), CPU usage is around 40 % (twice dxva2cb).

Before to install MPC-HC 32 bit (for compatibility with Avisynth 32 bit), I installed MPC-HC 64 bit and the CPU usage was around only 3 % with 1080p videos ! I used the default setting (DXVA activated but I don't know if LAV was used).
I had the same result (3 %) with MPC-HC 32 bit on XP 32 bit.
Does it mean that MPC-HC 32 bit works better on 32 bit OS than on 64 bit OS ?