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  • #16
    Originally posted by RealNC View Post
    XvMC also supports offloading decoding of mo comp, iDCT, and VLD ("Variable-Length Decoding", more commonly known as "slice level acceleration") for not only MPEG-2 but also MPEG-4 ASP and MPEG-4 AVC (H.264) video on VIA Unichrome (S3 Graphics Chrome Series) hardware.
    I don't think they actually had support for H.264 acceleration, neither in software nor hardware, only H.263 and maybe MPEG-4 ASP in addition to MPEG-2. Haven't used the driver myself though.

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    • #17
      Originally posted by chrisr View Post
      Are we just talking about just R500+ here? I do have older machines with CPUs barely capable of MPEG2: R100, for example. (Or possibly rv100 - it's a Radeon 7000.)
      If someone was inclined, MC acceleration could be implemented with shaders on all r3xx-r5xx hw. IIRC, MC was done with the 3D engine on older asics (r1xx/r2xx) as well, but there may have been some special bits in the pipeline to handle it due to the lack of shaders on the older hw.

      Originally posted by chrisr View Post
      I also happen to be a C developer with time on my hands (apart from WoW, which is like a black hole for free time) so what's the harm in a little extra functionality?
      Your best bet would be to study the video decode math and see what could be done on the 3D engine. One of the Xorg GSoC students implemented an MC interface gallium. You might want to look at that.

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      • #18
        Originally posted by deneb View Post
        I don't think they actually had support for H.264 acceleration, neither in software nor hardware, only H.263 and maybe MPEG-4 ASP in addition to MPEG-2. Haven't used the driver myself though.
        XvMC is a bit hit and miss on the Via chipsets as to whether the drivers support it or not. It is being actively worked on for the openChrome drivers...

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        • #19
          GSoC with XvMC

          Originally posted by agd5f View Post
          Your best bet would be to study the video decode math and see what could be done on the 3D engine. One of the Xorg GSoC students implemented an MC interface gallium. You might want to look at that.
          Do you mean this?:
          http://www.bitblit.org/gsoc/g3dvl/index.shtml

          This seems to imply that MC was done using shaders for the Nouveau project. So assuming that shaders are ARB, and therefore portable between NVIDIA and ATI hardware, doesn't this imply that the video decode math is already done?

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          • #20
            Yes, the idea is that it should be portable. The radeon-gallium3d-brach is just to incomplete to let the video decode run on it.

            Also the video decoding via gallium3d has still some issues and missing features, look at the last blog entry. It is for example still too slow. Maybe you could help out there?

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            • #21
              Originally posted by chrisr View Post
              Well obviously we all want accelerated MPEG4 / H.264 / VC-1 but that doesn't mean that I wouldn't want to accelerate MPEG2 either!
              Chrisr, all your points are valid. The question is whether the development community should invest their (limited) time in MPEG2 acceleration via XvMC or spend their time on MPEG4 instead.

              My feeling is that our time is better spent working on MPEG4, where even some modern systems could use help.

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              • #22
                Well VDPAU does not support MPEG4, only those codecs which are used by BlueRay.

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                • #23
                  Originally posted by Kano View Post
                  Well VDPAU does not support MPEG4, only those codecs which are used by BlueRay.
                  You mean MPEG-4 ASP (DivX, XviD, ...). It does support MPEG-4 AVC.

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                  • #24
                    Sure, but he mentioned MPEG4 and H264 - so I don't think he ment MPEG4 AVC twice.

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                    • #25
                      But that's the thing about development communities...

                      Originally posted by bridgman View Post
                      Chrisr, all your points are valid. The question is whether the development community should invest their (limited) time in MPEG2 acceleration via XvMC or spend their time on MPEG4 instead.

                      My feeling is that our time is better spent working on MPEG4, where even some modern systems could use help.
                      By all means, work on MPEG4 support; I can't help with that. However, with a small amount of guidance I could probably do something for MPEG2 - assuming that the GSoC has already written the shaders.

                      I managed to add zero-copy TFP support for R100/R200 using the exact same method, with a little help from Michel Danzer...

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                      • #26
                        Originally posted by Kano View Post
                        Sure, but he mentioned MPEG4 and H264 - so I don't think he ment MPEG4 AVC twice.
                        Maybe it is just confusion between the container and the codec. It is almost as pointless to accelerate mpeg4-asp as it is to accelerate mpeg2.

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                        • #27
                          > XvMC is a bit hit and miss on the Via chipsets as to
                          > whether the drivers support it or not. It is being
                          > actively worked on for the openChrome drivers...

                          Is there a chart somewhere showing which features
                          openChrome supports on which Via chips? Perhaps similar to

                          http://www.x.org/wiki/RadeonFeature

                          Comment


                          • #28
                            Not that I am aware off...

                            Though that might be something I could manage to arrange if the openchrome devs don't kill me for all my questions...

                            Comment


                            • #29
                              Just a quick commit,

                              The MPEG-2 Stream off devices such as the HDHomerun (1) (1920x1080) or HD-PVR are not the easiest to decode on an age'ed cpu. I have a 10-20 second sample 16MB. (just pm me for link, (upload via slow cable modem))

                              1: http://www.silicondust.com/products/hdhomerun

                              Regards,

                              Comment


                              • #30
                                > Both the European and North American TV standards now include
                                > MPEG4 as well as MPEG2. The move to MPEG4 seems to be happening
                                > very quickly, and right now XvMC only standardizes MPEG2 acceleration.

                                Show me a US TV station broadcasting mpeg4.

                                > Are you asking about MPEG2 (XvMC) or MPEG4 / H.264 / VC-1 ? They
                                > really are two different questions.

                                The immediate FCC created need is mpeg2, thus XvMC, which is what
                                I've been asking about. XvMC handles mpeg2 and there is talk about
                                having it do the newer stuff.

                                Out here in the real world, normal people don't buy a new computer
                                every three months to get the latest ueberphemon3++ 5.72 Ghz x16.
                                Full bitrate HD takes a lot more CPU than SD and computers in
                                the real world have trouble with it or can't do it at all.

                                Sure, longer term we will want support for the newer stuff.
                                But XvMC is the standard that the players already support,
                                It will take ages for the alphabet soup of proposed APIs
                                to get sorted out. Meanwhile the train wreck is scheduled
                                for 2009-02-17.

                                Maybe you should ask congress for bailout money to support the
                                DTV transition? :-/

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