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Thread: Intel Sandy Bridge VA-API Performance

  1. #31
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    Quote Originally Posted by crazycheese View Post
    You will not, granted you possess the clip.
    So if A/B==gfx cards of same owner, owning the clip and only publishing the results - its not a problem.
    But if A/B==different people with different machines they will all be required to license the clip, its logical. Yes, thats what Michael told me.
    The problem with using custom clips that cannot be used by everyone is that publishing results and comparison to other setups become meaningless to everyone except the actual tester.

    And if we create such clip - from big buck bunny lower bitrate h264 as source or multiple big buck bunny screens rendered from one lower bitrate formats into new file especially for phoronix test? It won't be commercial encode, the source is also free - should be no problem. Of course it will require some location to be buffered on the internet.
    What do you think?
    When it comes to video decoding performance you generally want a realistic "worst case" clip. Low bit rate clips do not stress the system enough to provide any meaningful data. When I'm shopping to purchase a truck for example, I don't see if it can handle a 25 pound bag of spuds if I possibly will be using it to haul around a camper.

  2. #32
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    Quote Originally Posted by deanjo View Post
    The problem with using custom clips that cannot be used by everyone is that publishing results and comparison to other setups become meaningless to everyone except the actual tester.
    Yes, yes - I didn't reply to Michael because of this too, its clear.


    Quote Originally Posted by deanjo View Post
    When it comes to video decoding performance you generally want a realistic "worst case" clip. Low bit rate clips do not stress the system enough to provide any meaningful data. When I'm shopping to purchase a truck for example, I don't see if it can handle a 25 pound bag of spuds if I possibly will be using it to haul around a camper.
    Say you take 4Mbit BBB sample and put it together 4x on same frame while resizing it to 1/4 of fullhd on each side. You have already 16Mbit/s detail stream. You can take cut and combine different moments from BB - the static as well as dynamic ones. With less/more decent editor you should be able to pick the most intensive segments. You could make a loop and play it several times within the test. There may be good advantages in such manually respinned test track - full control, no restriction to modification, no license problems for use in test. The only disadvantage I see is the resulting size(again depending on how long you want to make it) that should be stored somewhere.

  3. #33
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    Quote Originally Posted by crazycheese View Post
    Say you take 4Mbit BBB sample and put it together 4x on same frame while resizing it to 1/4 of fullhd on each side. You have already 16Mbit/s detail stream.
    Not quite, you have 4 x 4 Mbit streams. There are various issues with this as the various decoders have limitations as to how many HD streams they are capable of playing using the HW decoder. IIRC Nvidia officially only supports one, intel supports 2 HD streams and ATI supports one HD stream and one SD stream.

  4. #34
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    I should also note that for nvidia at least, even though it only officially supports one stream it seems that it is purely based on if the decoder has enough resources free to accommodate the additional load up to it's max capabilities.

  5. #35
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    Quote Originally Posted by deanjo View Post
    Not quite, you have 4 x 4 Mbit streams. There are various issues with this as the various decoders have limitations as to how many HD streams they are capable of playing using the HW decoder. IIRC Nvidia officially only supports one, intel supports 2 HD streams and ATI supports one HD stream and one SD stream.
    Yes, I'm also aware of this fact. However my proposal was completely different, unless I missunderstand you.

    My proposal was to combine four videostreams of the free licensed movie into one videostream using demux, decode, quality resize, picture-in-picture filters with final 16Mbit 2 pass compression.

    The other possibility is to generate huge amount of raw noise in fullhd frame and encode it into any preferable format, setting encoder two pass average bitrate @ desireable.

  6. #36
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    a 40 mbit peak file would be much better, average maybe 30 mbit for video.

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    Quote Originally Posted by crazycheese View Post
    Yes, I'm also aware of this fact. However my proposal was completely different, unless I missunderstand you.

    My proposal was to combine four videostreams of the free licensed movie into one videostream using demux, decode, quality resize, picture-in-picture filters with final 16Mbit 2 pass compression.
    The final bitstream since you are combining into one stream could be at any bit rate since you are reencoding. It's going to be far easier to encode from raw png and just get a good quality high bitrate video with peaks of video data @ 40 mbit. Like I say the best open movie that would be a tough decode would be elephant dreams where there isn't a lot of redundant data because of the massive amounts of detailed movement going on in the background.

  8. #38
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    OC the 720p60 tall ships clip on the free x264 Blu-ray and AVCHD ISO is also a nice test



    perhaps Michael should also house that in the Phoronix Test Suite tree along side other real life video clips i linked to OC

    http://forum.doom9.org/showthread.php?t=154183
    25th April 2010, 04:46
    read the tread for more info and links/thoughts for higher bitrate etc.

  9. #39
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    I've been an AMD/ATi fanboy for a long time. I really liked where they where heading in the opensource department too. That said ...

    wow, this does look like a really nice and open solution for a mediacenter/htpc. Being able to decode 1080p in hardware with opensource drivers is a big plus for me.

    I do have a question though, maybe slightly off-topic. AMD doesn't opensource this bit (yet) because the whole DRM debacle. Now AMD (and nVidia?) say they have specific asic's in their die's for this? UVD, purevideo. Does the intel video chip have this aswell? Or, like I always thought, is UVD, purevideo just some extra functions and does the driver/chip still do most of the heavy lifting via shaders?

  10. #40
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    Quote Originally Posted by oliver View Post
    Does the intel video chip have this aswell? Or, like I always thought, is UVD, purevideo just some extra functions and does the driver/chip still do most of the heavy lifting via shaders?
    I don't know about special unit to decode the video, but sandybridge itself has very strong hollywood sexual fantasy, ie drm (guess hence the name - sandy, ie filtering, bridge - to deliver content) that was heavily criticized. You can read about it if you google for sandybridge + drm, obviously.

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