Re: Accessing underlying AUGraph being used by quicktime
Re: Accessing underlying AUGraph being used by quicktime
- Subject: Re: Accessing underlying AUGraph being used by quicktime
- From: Brian Sheehan <email@hidden>
- Date: Thu, 26 Jan 2006 20:44:49 +0000
Craig,
I'm just learning the CoreAudio API at the moment, and I'm still
trying to get my head around what's doable or not. So just to confirm,
are you saying that the AUs used/instantiated through the quicktime
api can not be accessed in any way?
I suppose more generally I'd be interested to know if there was a way
of accessing an AUGraph or standalone AudioUnit that you didn't have a
reference for. For example, accessing the AudioUnit instances of other
running applications.
thanks for your help,
Brian
On 1/26/06, Craig Hansen-Sturm <email@hidden> wrote:
>
> Brian,
>
> QuickTime audio is making use of many of the standard AU's, the
> AudioConverter, and the OutputUnit.
> However, the infrastructure to "wire" these units together is opaque
> currently, and is not based on
> AU Graphs.
>
> At the time of the design, we were unclear whether there was
> sufficient interest from 3rd parties to provide
> an external API. I believe this wouldn't be difficult to do; however.
>
> --craig
>
>
> On Jan 26, 2006, at 10:39 AM, Brian Sheehan wrote:
>
> > Thanks for your response Brad.
> >
> > That's strange, cos the docs hint at some sort of facility for
> > doing this:
> >
> > "If you need to work with QuickTime at a lower level, to modify
> > individual video frames during playback, for example, or to add a
> > filter to the sound output, you need to work with the underlying
> > technology that QuickTime relies on for output. This will vary
> > depending on your platform and software revision.
> >
> > For example, QuickTime 7 for Mac OS X uses Core Audio for audio
> > output. To work with QuickTime audio at the low level, you should use
> > the Core Audio API. Older versions of QuickTime send audio output to
> > the Sound Manager (included in QuickTime for Windows). To work with
> > low level audio on these systems, you need to use the Sound Manager
> > API."
> >
> > What part of the Coreaudio does Quicktime use? Anything I can get my
> > hands on at all?
> >
> > thanks again,
> >
> > Brian
> >
> > On 1/26/06, Brad Ford <email@hidden> wrote:
> >>
> >> On Jan 26, 2006, at 10:15 AM, Brian Sheehan wrote:
> >>
> >>> Hi,
> >>>
> >>> The quicktime docs make a passing reference to this
> >>> (http://developer.apple.com/documentation/QuickTime/RM/Fundamentals/
> >>> QTOverview/index.html),
> >>> so it should be possible - how would I go about getting a
> >>> reference to
> >>> the AUGraph that is being used during playback of a movie using the
> >>> Quicktime API?
> >>
> >> This is quite impossible as QuickTime doesn't use AUGraph to play
> >> back audio.
> >>
> >>>
> >>> Just to give an idea of what sort of situation this might be used
> >>> in -
> >>> I want to use quicktime to playback a movie, but I want to filter
> >>> the
> >>> audio output through some AudioUnit.
> >>
> >> This is currently not possible through public API. Sorry.
> >>
> >> -Brad Ford
> >> QuickTime Engineering
> >>
> >>>
> >>> thanks,
> >>>
> >>> Brian
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