The Pinnacle system is a DV25 AVI video with 4 channels of
audio. The Avid system will only recognize two of the 4 audio
clips when they are quicktime wrapped. So yes I need to convert
the 4 channel audio clip into 2 two-channel stereo
tracks.
If the audio in the source is coming out of DV25 frames, each
containing 4 channels of audio, then QuickTime should be mixing that
into 2-channel audio automatically, without giving you the option of
seeing it as 4-channel audio.
I was given a
way by Dave to use Quicktime Pro and export (sound to aiff) two
channels at a time resulting in 2 stereo pairs.
If this worked, then perhaps your audio is encoding into a
separate audio track that is not a DV stream. If that's the
case, then your problem is much simpler.
This worked great but how
can I do this programmatically with quicktime?
There are many ways to skin this cat, and it depends on what your
consumer will actually do with the movie it gets.
For instance, if you just want to make a movie that has two
tracks that deliver stereo, but it doesn't matter how many channels
are in each one of them, then you could simply duplicate the 4-channel
track and set the first two channels to Unused in one of them, and the
other two channels in the other. They will still be 4-channel
tracks, but each will contribute only stereo (eg, you can individually
disable either track).
However, if the consumer requires that the tracks themselves be
two-channel, then you'll have to rewrite the file. This can be
simple and inefficient (eg, export two audio files, then import them
into a new movie) or complicated (extract the audio and add media
samples into a new movie as you go).
I suggest some searching and browsing in the QuickTime API on
developer.apple.com. Some things to look for:
to assign
channels in an audio track to Left, Right, Unused, etc
Export APIs to export to files and
InsertMovieSegment to load a second audio file into a new track in a
movie
MovieAudioExtraction
to get the
audio data out of the movie
NewTrackMedia / AddMediaSample
to add
audio data into a track
There are lots of code examples showing various pieces of this,
as well. If you want an Apple support engineer to help you write
this, you can initiate a paid DTS incident. See
<http://developer.apple.com/faq/techsupport.html>
Daniel Steinberg
QuickTime Engineering
On 6/29/06, Daniel Steinberg
wrote:
Unfortunately, QuickTIme does not
currently demultiplex the other two channels of audio from the DV
stream, it mixes the left and right channels together. I believe
there was a time when we couldn't reliably depend on all cameras
delivering silence on the two unused frames in 12-bit streams, and
things got stuck that way. It's on our list to fix.
Daniel Steinberg
QuickTime Engineering
At 11:48 AM -0400 6/29/06, no spam wrote:
Yes you can tell I don't know a great
deal about this :-)
We're trying to import a clip into our Avid system from a
Pinnacle system. The Pinnacle system is a DV25 AVI video with 4
channels of audio. The Avid system will only recognize two of
the 4 audio clips when they are quicktime wrapped. So yes I need
to convert the 4 channel audio clip into 2 two-channel stereo
tracks.
Thanks,
Mark
_______________________________________________
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
