Help me to understand PDC

[maralatho]

I'm using a buffer size of 64. In the PDC column of the Performance Meter I see some tracks are reporting a PDC of zero and others are reporting 64. Does this mean that my total buffer size is still just 64 or does it mean that 64 samples are being added to my buffer for a total size of 128? Or does it mean something else entirely?

[DarkStar]

Something-else.

Your buffer size dos not change.

In the example you described, Reaper delays the audio output of those tracks with zero PDC by 64 samples. That way those tracks will line up sonically with the tracks that have a PDC of 64.

Why 64? Well, plug-ins that have a latency ("delay") should report it to the host. Reaper will then delay the audio output by an integral number of buffers, more than the number of samples.

So:
-- a reported delay of 1-64 samples will be a PDC of 64 (one buffer),
-- a delay of 65-128 samples will be a PDC of 128 (2 buffers).
-- if you had two plug-ins on a track with delays of 32 and 16 samples, Reaper rounds up each one to 64 resulting in a PDC of 128.

[maralatho]

Got it. Thank you!

Originally Posted by DarkStar

Something-else.

Your buffer size dos not change.

In the example you described, Reaper delays the audio output of those tracks with zero PDC by 64 samples. That way those tracks will line up sonically with the tracks that have a PDC of 64.

Why 64? Well, plug-ins that have a latency ("delay") should report it to the host. Reaper will then delay the audio output by an integral number of buffers, more than the number of samples.

So:
-- a reported delay of 1-64 samples will be a PDC of 64 (one buffer),
-- a delay of 65-128 samples will be a PDC of 128 (2 buffers).
-- if you had two plug-ins on a track with delays of 32 and 16 samples, Reaper rounds up each one to 64 resulting in a PDC of 128.