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The UVD/UVD2 thread.

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  • The UVD/UVD2 thread.

    I make this thread with the intention of gathering information on the current state of usability of UVD and UVD2 in linux.

    I am a novice when it comes to understanding driver architecture and difficulties concerning them, so if anyone would like to give an introduction to why UVD / UVD2 as of now is not useable, it would be much appreaciated.

    I'll come with the first (obvious) update:

    In fact, the official release of Catalyst 8.10 doesn't have a whole lot worth talking about. It does have UVD Linux support enabled to accelerate video playback via the XvMC extension and their own HD video interface. However, all attempts at using XvMC with mplayer have failed thus far and AMD has been mum on how to actually use this feature. This looks like another feature we'll need to wait until Catalyst 8.11 to find out more.


    Now for some of my own questions:

    1. Will it ever be possible to use this feature? Will I ever be able to make the GPU decode my x264 encoded material?

    2. How will programs make use of this feature?

    3. As video tearing is a common problem at the moment many people are using built in graphics or a nVidia add-on card instead (in case of for example a 780g chipset) - will it be possible to make use of UVD when you are using another video card?

    Hope these questions make even remotely sense for you guys!

  • #2

    I'm able to use XvMc with xine only to play video.

    But, there is a little problem: Opening a video result to a display of black and white strips. To resolve, just switch to fullscreen and/or go back to windowed mode.
    Last edited by milambert; 23 October 2008, 12:51 PM.


    • #3
      Have you tested a x264 video and measured CPU load with and without XvMc?


      • #4
        1) I believe that XvMC can only (currently) accelerate Mpeg2, so when using it for h.264 it shouldn't be doing any acceleration.

        2) currently you have to choose a rendering backend. (in catalyst they may provide their own proprietary renderer

        3) Nope. Because video acceleration tends to be done in a series of stages acceleration tends to stay inside the gpu (well at least full bitstream decoding), and getting the two different cards to talk to each other would be a nightmare. But it would be nice to be able to seperate decode and rendering like in dxva2.
        Last edited by _txf_; 22 October 2008, 05:16 PM. Reason: actually answer the questions


        • #5
          Originally posted by milambert View Post

          I'm able to use XvMc with xine only to play video.
          Hi, are you shure you are using XvMc ?
          And xine is not a falling back to xv ?

          I wonder which libraries are used (and how) for the xvmc functions.
          I can not find them.

          (and the new libs which could provide XvMc and UVD
          are not used anywhere as far as I can tell. Even worse, they are not installed in a 64bit system (according to the install script
          because "maximus" is not ready for 64bit).

          Greetings Rene


          • #6
            Also, did you modify your XvMC wrapper to use the new AMD library? I thought I had already tried Xine to no avail but maybe I skipped over it.
            Michael Larabel


            • #7
              Originally posted by xyzzy View Post
              Hi, are you shure you are using XvMc ?
              And xine is not a falling back to xv ?
              You are right.

              If launching xine with 'verbose -V xvmc' option, I got tis error:

              video_out_xvmc: XvMC extension not present.
              So, Xine fall back to Xv.


              • #8
                i about to buy a 790fx board and will be watching dvd's on it, so working video playback is not optional.

                it seems that video works for some and doenst work for others. does anyone know what combination of libraries and kernel versions work ?

                i assume everyone is 64 bit kernel and libs ?

                xorg 1.4 or 1.3 work ?

                xv work ? (all i need is dvd playback)

                if none of those work, how well does software decoding work with mplayer? i suppose software decoding works fine but i kinda doubt it would scale to 1920 x 1200 very well. could anyone tell me if this works.

                btw... i would be installing gentoo on new 790fx board, i dont think specific packages should be a problem.




                • #9
                  Hmm it seems like I wont be using UVD to decode my movies then. But im in the process of finding some hardware for my media center, and im still considering a 790g chipset and just use nvidia card till driver support is adequate.

                  Think a 4800 X2 cpu can handle 720p or 1080p x264 videos?

                  I will probably regularly be checking how good the drivers are for UVD and will bump this thread when that happens - unless someone beats me to it!

                  Btw, any recommendations on a small sized touchscreen with good support in linux?


                  • #10
                    Remember that there are several levels of "video acceleration" to think about :

                    1. Current state for 780/790- shadowfb only, render done by CPU, decode done by CPU

                    2. "Real soon now" state for 780/790 - render acceleration done by GPU via Xv, decode done by CPU

                    3. Possible next step -- render acceleration done by GPU via Xv, motion comp portion of decode acceleration done by GPU, remaining decode acceleration done on CPU. Probably need extensions to XvMC in order to handle odd block sizes for H.264/VC-1.

                    4. Remaining decode done on GPU, possibly on UVD/UVD2

                    The point here is that step 2 will go a long way to reducing CPU overhead and that is already in the works.
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