AUTimePitch and latency
AUTimePitch and latency
- Subject: AUTimePitch and latency
- From: "Roni Music" <email@hidden>
- Date: Sat, 3 Dec 2005 13:57:12 +0100
Hi,
I'm doing some tests with the AUTimePitch converter. I'm driving the Audio
Unit rendering process myself as described in the Audio Unit Rendering docs
and everything works fine except the latency compensation.
I'm calling AudioUnit GetProperty() with the kAudioUnitProperty_Latency flag
after setting up everything (rate, pitch etc) (actually for this test I'm
using a rate setting of 1.0 and pitch setting of 0, i.e. no change and
render quality max).
The converter reports it's latency as 75.4 milliseconds or 3325 frames at
44100 Hz sample rate. When I compare the processed file with the original
file (compensating with the reported latency), the converted audio is around
550 samples frames to early (about 12 milliseconds).
If I switch to using the VariSpeed converter (same settings i.e. no change),
it reports it's latency as 1.09 milliseconds or 48 sample frames. When I
compare the processed file with the original file (again compensating with
the reported latency), the audio is perfectly alligned.
Also, if I change the kAudioUnitProperty_Quality setting to medium, it
reports the same latency but now the converted audio is 350 samples frames
(8 milliseconds) to early.
To me it seems that the AUTimePitch is reporting a wrong/too low latency
value or is there anything I'm missing?
Dual 1 GHz G4, OS X 10.4.3 using XCode 2.2
Thanks for any help
Rolf
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