Latency and AUTimePitch
Latency and AUTimePitch
- Subject: Latency and AUTimePitch
- From: Ashley Allen <email@hidden>
- Date: Wed, 11 Jun 2008 17:36:12 -0700
Hi,
I submitted a question yesterday regarding AUTimePitch and latency.
Basically, I can create an AUGraph with AUFilePlayer units that successfully arranges and renders samples accurately with no gaps at the beginning or end of the file. In other words, if I want a 4 bar loop from my samples the rendered file is precisely 4 bars and timing is on point. All samples in this working scenario have the same beats per minute.
If I take the above AUGraph and add an AUTimePitch and AUFilePlayer unit to play a sample with a different beats per minute the timing is off. A latency is introduced by the AUTimePitch unit. How do I compensate for this? All AUFilePlayers are on separate subgraphs that connect to an AUStereoMixer. Each subgraph ends with a genericOutputUnit. I tried setting the kAudioOutputUnitProperty_StartTimestampsAtZero on the genericOutputUnit which did not solve the problem. It's as if I have to prime the AUTimePitch unit. Is that possible?
I created another simple scenario of an AUGraph that contained an AUStereoMixer connected to a subgraph that contained an AUTimePitch unit and an AUFilePlayer. When I playback a single sample and render output to a file for a 4 bar loop, a gap starts at the beginning of the file which throws off the timing of the loop. If I take the AUTimePitch unit out, the gap at the beginning is gone and the timing is perfect. Is this gap a predictable offset that I can just chop off? What am I not getting?
Thanks in advanced ...
Ashley
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