Quartz Comp and Audio input??

  • I am looking for a way to:

    A) have Quartz composer grab its audio input from whetever is going to the
    audio output (ie whatever is playing on the speakers).

    OR

    B) a way in Cocoa to send the audio output to the audio input so Quartz
    Composer will pick it up.

    OS 9 used to have a "play through" checkbox in the Sound control panel that
    did this.

    Thanks,

    Trygve
  • On 11 Sep 07, at 13:41, Trygve Inda wrote:
    > I am looking for a way to:
    >
    > A) have Quartz composer grab its audio input from whetever is going
    > to the
    > audio output (ie whatever is playing on the speakers).
    >
    > OR
    >
    > B) a way in Cocoa to send the audio output to the audio input so
    > Quartz
    > Composer will pick it up.
    >
    > OS 9 used to have a "play through" checkbox in the Sound control
    > panel that
    > did this.

    Playthrough was actually the opposite from what you're thinking of -
    it'd route audio input to output, not the other way around. For this
    application, take a look at Soundflower.
  • > On 11 Sep 07, at 13:41, Trygve Inda wrote:
    >> I am looking for a way to:
    >>
    >> A) have Quartz composer grab its audio input from whetever is going
    >> to the
    >> audio output (ie whatever is playing on the speakers).
    >>
    >> OR
    >>
    >> B) a way in Cocoa to send the audio output to the audio input so
    >> Quartz
    >> Composer will pick it up.
    >>
    >> OS 9 used to have a "play through" checkbox in the Sound control
    >> panel that
    >> did this.
    >
    > Playthrough was actually the opposite from what you're thinking of -
    > it'd route audio input to output, not the other way around. For this
    > application, take a look at Soundflower.
    >

    Maybe there is a better solution here. My goal is to build something like
    the iTunes visualizer to display images, tweaked by the waveform of an
    in-memory (playing) quicktime movie.

    My though originally was to have a separate movie (Quartz Composer really),
    but perhaps there is a better way.

    Any help is appreciated.

    Thanks,

    Trygve
  • On Sep 11, 2007, at 1:41 PM, Trygve Inda wrote:

    > A) have Quartz composer grab its audio input from whetever is going
    > to the
    > audio output (ie whatever is playing on the speakers).

    This is not possible. The lower levels (Core Audio) doesn't have a
    method to obtain the system audio mix.

    > B) a way in Cocoa to send the audio output to the audio input so
    > Quartz
    > Composer will pick it up.

    Same issue.
    --
    David Duncan
    Apple DTS Quartz and Printing
    <david.duncan...>
  • > On Sep 11, 2007, at 1:41 PM, Trygve Inda wrote:
    >
    >> A) have Quartz composer grab its audio input from whetever is going
    >> to the
    >> audio output (ie whatever is playing on the speakers).
    >
    > This is not possible. The lower levels (Core Audio) doesn't have a
    > method to obtain the system audio mix.
    >
    >> B) a way in Cocoa to send the audio output to the audio input so
    >> Quartz
    >> Composer will pick it up.
    >
    > Same issue.

    Well, Sound Flower seems to be able to channel the audio mix back to a new
    input that QC could read I think, but that is messy.

    What I am ultimately trying to do is an audio visualizer for a QT movie
    playing in memory but not existing on disk.

    Trygve
  • Look in the archives of the CoreAudio-api list - this has been
    discussed there many times. Check the thread "Output Capture" from
    July 2007 for the most recent round.

    On Sep 11, 2007, at 5:19 PM, Trygve Inda wrote:

    >> On Sep 11, 2007, at 1:41 PM, Trygve Inda wrote:
    >>
    >>> A) have Quartz composer grab its audio input from whetever is going
    >>> to the
    >>> audio output (ie whatever is playing on the speakers).
    >>
    >> This is not possible. The lower levels (Core Audio) doesn't have a
    >> method to obtain the system audio mix.
    >>
    >>> B) a way in Cocoa to send the audio output to the audio input so
    >>> Quartz
    >>> Composer will pick it up.
    >>
    >> Same issue.
    >
    > Well, Sound Flower seems to be able to channel the audio mix back
    > to a new
    > input that QC could read I think, but that is messy.
    >
    > What I am ultimately trying to do is an audio visualizer for a QT
    > movie
    > playing in memory but not existing on disk.
    >
    > Trygve
  • On Sep 11, 2007, at 2:19 PM, Trygve Inda wrote:

    > Well, Sound Flower seems to be able to channel the audio mix back
    > to a new
    > input that QC could read I think, but that is messy.

    From what I can tell, Sound Flower is creating a new audio device
    for the system that does this. This feature isn't built into Core
    Audio directly, but if your willing to work inside the kernel you can
    always do this yourself (if you can convince the other device to
    provide the audio to your driver).

    There is no built in way to get the audio being sent to any given
    audio device however. Sound Flower only works because it is a device.

    > What I am ultimately trying to do is an audio visualizer for a QT
    > movie
    > playing in memory but not existing on disk.

    I believe you can use the Audio Extraction APIs in Quicktime to get
    audio out of the movie and then do whatever you wish with it. You
    would have to create your own protocol to send the audio to a Quartz
    Composition however.
    --
    David Duncan
    Apple DTS Quartz and Printing
    <david.duncan...>
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