On Dec 28, 2005, at 4:30 AM, Jeremy Bernstein wrote:
Dear qt-api:
I would like to route audio from one part of my software (out of a
QuickTime movie) to another part (a non-QT-based audio processing
environment), more or less in real-time. Until now, I have assumed
that I would need to write a special virtual device driver for
this, although the good people at coreaudio-api seem to think
otherwise. From what they say, and what I know so far, this leaves
a couple of options:
- Use the Audio Extraction API (or simple MovieExport Components
for compatibility across several versions of QT) to get the data,
and manually (attempt to) play it back in sync with the movie.
Yes. And the Movie Audio Extraction API's are much more efficient
than using Movie Export components/PutMovieIntoTypedHandle for this
type of thing. And yes, the problem with this approach is that you
have to manually synchronize to video.
- Same, but by stepping through the media samples to retrieve the data
Don't do this. Movie Audio Extraction is much better to use for
this, because you get the benefit of using QuickTime's audio engine
to read the media, decompress it, and mix it. So it's very easy to
extract audio from, say, multi-audio track movies.
or, and this is the big hope:
- Create a custom Audio Context to take care of all of that mess
automatically.
We currently do not support the creation of custom AudioContexts that
play somewhere other than to a HAL device.
However, I can't find any documentation as to how one creates an
Audio Context, beyond the generation of one from a device driver
(which is why I thought I would have to write my own driver). Is
there some way to create a "special" Audio Context which I could
use to simply re-route/process raw samples? Or am I stuck with the
first two options?
No, unfortunately you're stuck with the first option. Or you could
write a virtual audio device driver, which would send you back to the
core-audio list (aren't infinite loops fun?).
-Brad Ford
QuickTime Engineering
Thanks,
jb
_______________________________________________
Do not post admin requests to the list. They will be ignored.
QuickTime-API mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quicktime-api/email@hidden
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
QuickTime-API mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quicktime-api/email@hidden
This email sent to email@hidden
References:
>Audio Context (From: Jeremy Bernstein <email@hidden>)
