When DXVA is enabled, which decoder is used?

Microsoft Windows specific usage questions
Forum rules
Please post only Windows specific questions in this forum category. If you don't know where to post, please read the different forums' rules. Thanks.
kurkosdr
Cone that earned his stripes
Cone that earned his stripes
Posts: 101
Joined: 14 Jun 2009 00:36

When DXVA is enabled, which decoder is used?

Postby kurkosdr » 26 Apr 2010 21:21

Hi there,

When I play a video with VLC 1.1.0 pre2, and DXVA is enabled, which decoder is used? Is it the excellent decoder from ffmpeg VLC has, or some no-name decoder from ATI/NVIDIA nobody has tested in terms of quality?

Thanks,
kurkosdr

VLC_help
Mega Cone Master
Mega Cone Master
Posts: 25661
Joined: 13 Sep 2006 14:16

Re: When DXVA is enabled, which decoder is used?

Postby VLC_help » 27 Apr 2010 11:36

Decoder source code is from FFMPEG, but it uses DXVA API to do the decoding steps.

kurkosdr
Cone that earned his stripes
Cone that earned his stripes
Posts: 101
Joined: 14 Jun 2009 00:36

Re: When DXVA is enabled, which decoder is used?

Postby kurkosdr » 27 Apr 2010 17:47

Decoder source code is from FFMPEG, but it uses DXVA API to do the decoding steps.
So, the decoding is done by ffmpeg code, but it uses the GPU instead of the CPU?

I was under the impression that DXVA was a decoder embedded to the video card, and the player's decoder wasn't used at all.

Jean-Baptiste Kempf
Site Administrator
Site Administrator
Posts: 37523
Joined: 22 Jul 2005 15:29
VLC version: 4.0.0-git
Operating System: Linux, Windows, Mac
Location: Cone, France
Contact:

Re: When DXVA is enabled, which decoder is used?

Postby Jean-Baptiste Kempf » 27 Apr 2010 21:13

Decoder source code is from FFMPEG, but it uses DXVA API to do the decoding steps.
So, the decoding is done by ffmpeg code, but it uses the GPU instead of the CPU?

I was under the impression that DXVA was a decoder embedded to the video card, and the player's decoder wasn't used at all.
No, decoding is done by GPU manucturer, not ffmpeg.
Jean-Baptiste Kempf
http://www.jbkempf.com/ - http://www.jbkempf.com/blog/category/Videolan
VLC media player developer, VideoLAN President and Sites administrator
If you want an answer to your question, just be specific and precise. Don't use Private Messages.

McLion
Blank Cone
Blank Cone
Posts: 74
Joined: 29 Jan 2010 15:54
Location: Switzerland

Re: When DXVA is enabled, which decoder is used?

Postby McLion » 29 Apr 2010 14:17

Just to be sure ... we are taking about DXVA2, not DXVA, right?
DXVA is not supported, only DXVA2, correct?

napx
Blank Cone
Blank Cone
Posts: 30
Joined: 23 Aug 2009 18:49

Re: When DXVA is enabled, which decoder is used?

Postby napx » 29 Apr 2010 14:34

Decoder source code is from FFMPEG, but it uses DXVA API to do the decoding steps.
So, the decoding is done by ffmpeg code, but it uses the GPU instead of the CPU?

I was under the impression that DXVA was a decoder embedded to the video card, and the player's decoder wasn't used at all.
No, decoding is done by GPU manucturer, not ffmpeg.
This is exactly why I'm more excited about the possibility of multicore decoding than GPU decoding in VLC. I think it is more in VLC's tradition that the CPU (therefore the tried and true ffmpeg backend) does the work. I also think there are less variables to worry about in CPU-land.

Jean-Baptiste Kempf
Site Administrator
Site Administrator
Posts: 37523
Joined: 22 Jul 2005 15:29
VLC version: 4.0.0-git
Operating System: Linux, Windows, Mac
Location: Cone, France
Contact:

Re: When DXVA is enabled, which decoder is used?

Postby Jean-Baptiste Kempf » 29 Apr 2010 14:40

Just to be sure ... we are taking about DXVA2, not DXVA, right?
DXVA is not supported, only DXVA2, correct?
Yes.
Jean-Baptiste Kempf
http://www.jbkempf.com/ - http://www.jbkempf.com/blog/category/Videolan
VLC media player developer, VideoLAN President and Sites administrator
If you want an answer to your question, just be specific and precise. Don't use Private Messages.

kurkosdr
Cone that earned his stripes
Cone that earned his stripes
Posts: 101
Joined: 14 Jun 2009 00:36

Re: When DXVA is enabled, which decoder is used?

Postby kurkosdr » 10 May 2010 18:45

Here comes the million dollar question:

How can I be sure that the manufacturer's GPU decoder will be as good as the ffmpeg's decoder?

There are at least 3 different GPU decoder implementations out there (Intel, ATI, NVIDIA) and there is no guarantee all of them will be as good as ffmpeg, since ffmpeg doesn't have any control over the decoding process (when using DXVA, ffmpeg just submits the video for decoding and then receives the decoded video, right?).

Jean-Baptiste Kempf
Site Administrator
Site Administrator
Posts: 37523
Joined: 22 Jul 2005 15:29
VLC version: 4.0.0-git
Operating System: Linux, Windows, Mac
Location: Cone, France
Contact:

Re: When DXVA is enabled, which decoder is used?

Postby Jean-Baptiste Kempf » 11 May 2010 12:42

How can I be sure that the manufacturer's GPU decoder will be as good as the ffmpeg's decoder?
You cannot. You can just hope.
Jean-Baptiste Kempf
http://www.jbkempf.com/ - http://www.jbkempf.com/blog/category/Videolan
VLC media player developer, VideoLAN President and Sites administrator
If you want an answer to your question, just be specific and precise. Don't use Private Messages.

kurkosdr
Cone that earned his stripes
Cone that earned his stripes
Posts: 101
Joined: 14 Jun 2009 00:36

Re: When DXVA is enabled, which decoder is used?

Postby kurkosdr » 11 May 2010 18:34

How can I be sure that the manufacturer's GPU decoder will be as good as the ffmpeg's decoder?
You cannot. You can just hope.
So I guess I should wait for 1.2 which will have multicore support. This will be the best, IMO, because the trusted ffmpeg decoder is used, while even a CoreDuo T2400 should be able to handle the load of 1080p h264.

(I never liked DVXA2 much. As the YUV -> RGB debacle in ATI/NVIDIA drivers showed us, code from GPU manufacturers is not to be trusted)

BTW, can I have DXVA2 on while having the YUV->RGB conversions off?

Jean-Baptiste Kempf
Site Administrator
Site Administrator
Posts: 37523
Joined: 22 Jul 2005 15:29
VLC version: 4.0.0-git
Operating System: Linux, Windows, Mac
Location: Cone, France
Contact:

Re: When DXVA is enabled, which decoder is used?

Postby Jean-Baptiste Kempf » 12 May 2010 16:03

Yes, you can.
Jean-Baptiste Kempf
http://www.jbkempf.com/ - http://www.jbkempf.com/blog/category/Videolan
VLC media player developer, VideoLAN President and Sites administrator
If you want an answer to your question, just be specific and precise. Don't use Private Messages.


Return to “VLC media player for Windows Troubleshooting”

Who is online

Users browsing this forum: No registered users and 100 guests