[n00b]Audio Graph AUConverter : stereo -> mono and resampling

Discussion in 'Mac Programming' started by Palad1, Sep 3, 2008.

  1. macrumors 6502a


    Feb 24, 2004
    London, UK

    I'm writing my first audio graph and I'm entering a world of undocumented pain :eek:

    I want to use the audio graph to convert any file [ie. mp3/aac/aiff] to linearpcm float mono 44100hz, and then do some weird stuff with it.

    So I have set-up a graph, added the AUConverter, set its input SoundFormat property to match the file I want to convert, set the input callback, so far so good.

    1/ how can I instruct AUConverter to output a mono stream?

    2/ In my input callback, can I send the raw file as read from disk? Won't the ID3 tags/comments wreck havoc on my graph?

    3/ If I register a RenderCallback on the AUConverter node, will I be able to change what's being sent to the next node? I don't really wish to create my custom audio unit for what I'm going to do.

    4/ How does the threading work? Is the input callback going to be called when the output buffer runs out? I'm using AudioQueue to prime 16 buffers so I have continuous playback, how could this translate in this graph? I don't see anything about buffering data...

    5/ Thanks :)

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