kAudioUnitSubType_MultiChannelMixer seems to apply fade-in: Possibly to prevent?
kAudioUnitSubType_MultiChannelMixer seems to apply fade-in: Possibly to prevent?
- Subject: kAudioUnitSubType_MultiChannelMixer seems to apply fade-in: Possibly to prevent?
- From: Michael Tyson <email@hidden>
- Date: Sat, 26 Jan 2013 15:10:26 +1100
Hello,
I just discovered that kAudioUnitSubType_MultiChannelMixer seems to apply an initial ~25ms fade-in, per-input for inputs that have an initial sample value greater than some small, nonzero threshold.
For example, here's the result of mixing two sine waves together, the left channel starting at full +ve amplitude, the right channel starting at the zero crossing:
I'm using the mixer to merge two loops, for subsequent looped playback, which presents obvious problems, as there is now a discontinuity at the loop boundary:
Does anyone have any thoughts on how it might be possible to prevent this unwanted fade-in from occurring?
In the absence of any better idea I think I might, as part of the init process, simply pass 256 zero samples or so through the mixer to bypass this mysterious feature, but it'd be interesting to know if there's a better strategy.
Many thanks, Michael
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