Playing multiple video streams - before compression and after compression

Discussion in 'Amateur Video Production' started by Taras_96, Dec 20, 2006.

  1. Taras_96

    Taras_96 Guest

    Hi everyone,

    I'm currently using VirtualDubMod to compress some home videos I have
    on my PC. VirtualDubMod is pretty good except that I don't think the
    output stream shows the video stream after compression (I know that it
    shows the output after applying desired filters, such as brightness). I
    would like a program that can play two movies simultaneously so that
    you can see by direct comparison with the original source the resulting
    loss of quality due to compression. If the program also includes
    compression capabilities than that would be great. Preferably the
    program should be free (which I don't think is unrealistic as the
    program isn't doing too much). Does anyone know if something like this

    That is, it should load up movie one in one section of the screen, load
    up movie two (the compressed version) in another section of the screen,
    and when the user presses play it should play both movies.


    Taras_96, Dec 20, 2006
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  2. Taras_96

    Jukka Aho Guest

    You could use AviSynth for this, in combination with VirtualDub. See
    these links for more information:


    For example, if the videos are of same size (pixel resolution) this
    simple AviSynth script should do what you want:

    --- 8< ---

    v_original = DirectShowSource("myvideo.avi")
    v_original = ConvertToRGB24(v_original)

    v_compressed = DirectShowSource("myvideo.mpg")
    v_compressed = ConvertToRGB24(v_compressed)

    StackHorizontal(v_original, v_compressed)

    --- 8< ---

    (If they're not of the same size you could further tweak the script to
    include black borders around the smaller video.)
    Sorry, AviSynth does not do that.
    Jukka Aho, Dec 20, 2006
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  3. Taras_96

    Ken Maltby Guest

    You can get two iterations of your player, like Media
    Player Classic running at the same time, easily enough.
    If you pause the first one until the second one catches
    up, it's pretty simple, to have them both playing.

    If you needed something more precise (and I don't
    see why you would) you could try XML or even a
    batch file to launch them in a syncronized fashion.

    Ken Maltby, Dec 20, 2006
  4. Taras_96

    Taras_96 Guest


    Thanks for the replies. Znark, your script worked perfectly! Thanks!

    Taras_96, Dec 20, 2006
  5. Taras_96

    Ken Maltby Guest

    But it's not exactly a comparision of the actual results. You
    are comparing the results of VDub's conversions to RGB, and
    it's display of that. You are comparing VDubs performance
    in one case from an .avi (of some kind) source file, against its
    performance from an .mpg (of some kind) source file. Keep
    in mind that VDub will be using totally different code to each

    There should be no common path of components to convert
    the two so different sources, just as there are different
    components used to playback the two different sources. But
    a comparison of the playback, is closer to a comparison
    of the results. (Even though some players do better with one
    than the other. )

    Ken Maltby, Dec 23, 2006
  6. Taras_96

    V Green Guest

    If you're not running Vista yet (which has dropped
    WMP6.4), you can still start
    as many instances of WMP 6.4 as you want and play
    the content simultaneously (you will have to press Play)


    Rendering should be correct, per Ken's observation.
    V Green, Dec 23, 2006
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