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Active Contributor
derrick
Posts: 30
Registered: ‎11-17-2006
Message 1 of 3 (250 Views)

Unable to set audio offset for newly created audio clip

250 Views, 2 Replies
04-28-2007 10:23 PM
This might be related to my previous post...
I'm creating a new clip with a non-zero start TC, and then I create audiostream children of the clip.

Since the AudioSampleOffset is relative to the start TC, when I create the audio clips I try to set the offset to compensate for that. However, it does not seem to have any effect... when I ask for the clip's format, the metadata says the offset is 0 and in the Flame UI there's an audio slip equal to whatever my start TC was. For example, if I set the start TC to 00:00:04+01 in 24fps video, the flame reports an audio slip of 97.

How can I make the audio slip be 0? Message was edited by: asboy
Contributor
grattor
Posts: 16
Registered: ‎12-05-2006
Message 2 of 3 (250 Views)

Re: Unable to set audio offset for newly created audio clip

04-30-2007 05:57 AM in reply to: derrick
Yes, that was the key element of my last post on the other thread.

Audio offset is *not* relative to start TC -- it's an absolute expresion of audio start TC expressed in samples.

Assuing your audio and video start at the same time, you set a video start TC and then lay down the audiostream with an offset value in samples that equals the video start TC.

If start TC is 00:00:04+01 = 97 frames, therefore should be (if 48 KHz) 97 x 48000.
Active Contributor
derrick
Posts: 30
Registered: ‎11-17-2006
Message 3 of 3 (250 Views)

Re: Unable to set audio offset for newly created audio clip

05-01-2007 12:11 AM in reply to: derrick
> Audio offset is *not* relative to start TC -- it's an absolute expresion of audio start TC expressed in samples.

Yes, sorry. That's what I meant to say, but I said the exact opposite.

I explained this in my other recent thread, but for the record, the problem I describe here is because I was trying to set the audio offset with code like this:
audio_format.setMetaData( some-string );
but I also needed to do this:
audio_format.setMetaDataTag( "IFFFS_XML" );
and I had not done that.
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