inOutputTime accuracy?
inOutputTime accuracy?
- Subject: inOutputTime accuracy?
- From: Jim Dolan <email@hidden>
- Date: Thu, 15 Aug 2002 10:08:00 -0400
Hi -
My application needs to keep track of the sample position as it is playing.
During the first output IOProc I take inOutputTime.mSampleTime and use that
as an initialOffsetTime to the first sample that will be played. Later when
I check for the sample position I ask the device for the current time and if
the current time has passed the initialOffsetTime I know that we are now
playing samples and can start incrementing the composition sample position.
The sample position is roughly the currentTime - initialOffsetTime. This
seems to work fine except that I do not think that the original
inOutputTime.mSampleTime is accurate. I am trying to sync audio to video
and I notice that I need to substract 3k samples from that initial offset to
get them to line up. As though the first sample is being played earlier than
I was told in the IOProc. Once we begin, the relative accuracy from IOProc
to IOProc is very good, but the start time seems wrong. I am using a 4096
sample frame size.
Is there a bug here or is there something that I am still not accounting
for?
Thanks for your help...
Jimmy D.
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.