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Quicktime and 24 bit audio - Mac Programming

I'm trying to read in a 24 bit audio file using quicktime, but I keep hitting problems. I can do a GetMediaSampleDescription() on the audio track of a file, and although the dataFormat field of the SoundDescription that comes back varies with the bit depth (e.g. k24BitFormat for 24 bit audio), the sampleSize field never exceeds 16! I'd like to convert between file types using ConvertMovieToFile() as well, but this conversion always seems to return a file with a bit depth of 16, even when I had it a component that says that I'm asking for something else. Has anyone ...

  1. #1

    Default Quicktime and 24 bit audio


    I'm trying to read in a 24 bit audio file using quicktime, but
    I keep hitting problems.

    I can do a GetMediaSampleDescription() on the audio track of
    a file, and although the dataFormat field of the SoundDescription
    that comes back varies with the bit depth (e.g. k24BitFormat for
    24 bit audio), the sampleSize field never exceeds 16!

    I'd like to convert between file types using ConvertMovieToFile()
    as well, but this conversion always seems to return a file with
    a bit depth of 16, even when I had it a component that says that
    I'm asking for something else.

    Has anyone else hit these limitations, or know of a work-around?

    david
    david Guest

  2. #2

    Default Re: Quicktime and 24 bit audio

    In article
    <magnus.acs.ohio-state.edu>,
    david ralley <com> wrote: 

    This is a limitation of the current sound description handles. You can
    store audio into QuickTime movies in higher bit depths by doing them as
    "compressed" samples rather than raw. As for reading things out, that
    would need to be done by hand.

    The QuickTime team is aware of the issue.
    Tom Guest

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