Jack-Audio process callback time period/Rate

Programming applications for making music on Linux.

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Jack-Audio process callback time period/Rate

Post by nahumb »


I'm using Jack API in a synthesizer c++ program I'm developing running on a Raspberry Pi 4.

Sample rate is 44100 ( jackSampleRate = jack_get_sample_rate(client_out); )

Buffer size is set to 512 ( jack_set_buffer_size(client_out, _JACK_AUD_PERIOD_SIZE); ) (#define _JACK_AUD_PERIOD_SIZE 512).

Calculated process callback rate is 512/44100 = 11.6mSec.
However, actual process callback is initiated every 5.8mSec (with nframes = 512).

Any idea why the process callback rate is x2 than I expect it to be? (or my assumption is wrong? Why?)



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Re: Jack-Audio process callback time period/Rate

Post by folderol »

I don't think you can have less than two periods per buffer. Presumably one or other is being quietly adjusted.

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