videoDecoders

Discussion in 'iOS Jailbreak & Cydia' started by onyxd, Oct 29, 2007.

  1. onyxd

    onyxd New Member

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    ei! could somebody make a decoder for avi or divx files???

    theres a folder for video decoders in /System/Library/VideoDecoders and it only contains H264H1.videodecoder and MP4H1.videodecoder...


    will it work if someone makes AVIH1.videocoder or DIVXH1.videodecoder?

    so that we will be able to watch divx videos or tv shows without converting them!!!
  2. kinematic@yahoo.com

    kinematic@yahoo.com New Member

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    Until some developer gets the SDK it will be challenging to recompile the decoders to work with the ARM processor blindly. I don't suspect that it will be difficult to do once that is released. I for one would like to see Flip4Mac wmv decoders ported for the iPhone/iPod Touch. I suspect February will be when the next Firmware is released and with it, more video formats (hopefully flash video and a wmf codec)

    But take this with a grain of salt because apparently my lack of knowledge in video as one poster accused me of doesn't give me a right to make an opinion on this.

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  3. Jerrie85

    Jerrie85 New Member

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    kinematic, you're right in the sense that they have yet to release a SDK for interfacing to the hardware registers to enable video decoding, but there's more to it than meets the eye:

    you can decode video either through pure software decoding, OR coupled with hardware acceleration;

    in the ipod touch, the processor they used is a Samsung S3C6400 (i think), to support the bitrates they have in the MP4/H.264 video stream, combined with the complexity of the decoding, and the speed of the ARM processor (max 667Mhz), you'd most probably need a hardware assist to pull this off

    the chip has MPEG4, H.264 hardware acceleration support already, so they have drivers talking to registers to configure this interface - the chip also supports VC-1, and WMV9

    so short answer, no it won't be possible to integrate Xvid, or DivX support into these devices - it might be if they cross compile the Xvid/Divx sources for this chip, but it might not be able to pull it off in real-time

    However, you can still write drivers for WMV9 and VC-1 since hardware assist exists for those, and that is DEFINITELY realizble

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    Hope it helps
  4. macdog303

    macdog303 Member

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    I wish i had the slightest idea on how to get codecs working or even know how they work. Soo mysterious to me.
  5. kinematic@yahoo.com

    kinematic@yahoo.com New Member

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    http://www.samsung.com/global/busin...nfo.do?fmly_id=229&partnum=S3C6400&&ppmi=1427

    Wow that is a nice chip set... Apparently it has an integrated 3D engine in it as well. I'm guessing that's what the OpenGL is accessing. I'm also impressed at how large of a display that little chip can push too. I wonder if they will offer an HDMI solution? Because it will surly come close to driving 720p.

    I'm a little confused about DivX, as I thought is an MPEG-4 standard... just Part2 not Part10 like H.264. So correct me in this, is it still not possible for the chip to process DivX being that it's an early version of the MPEG-4 standard?
  6. Jerrie85

    Jerrie85 New Member

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    It has an integrated 3D engine yes, but i'm pretty sure there isn't an OpenGL wrapper on the touch that communicates with this engine

    and as for divx vs. h.264 (or Mpeg4 part-2 vs. part 10), they are totally different codecs despite being subclassed under the same subtree
    h.264 is an order magnitude more complex in terms of algorithms used, while divx/xvid use a smaller subset, but slightly different, computationally easier algorithms

    the hardware decoder inside the chip expects h.264 video in a specific format, and does not have the flexibility of accepting it in divx form - hence, accelerating divx through hardware is not possible for this chip

    a software solution is possible, perhaps someone can port xvid to the touch; the source code is openly available, and cross compiling should be a breeze; the portion that remains would be to interface to the graphics driver on the touch
  7. x2005gct

    x2005gct New Member

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    So what's the good news now, haven't they released an SDK? Does that mean that this would now be possible?
  8. optimo

    optimo New Member

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    No

    the answer is always no. xvid(h263) is too varied in encoding technique, and most of the nicer ones support computations that are not feasible for ipod hardware. Everyone has moved on , h264 is a superior format.

    the only acceptable h263 files are the ones that are low complexity and in the mp4 container
  9. steve088

    steve088 New Member

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    is that your final answer?
  10. legallyillegal

    legallyillegal New Member

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    i feel you do not know what you are talking about. it is a little more complicated.

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