How is the frameCount parameter defined in the data_callback function?

[yanostulens]

Hello,

I'm currently using miniaudio for audio playback on an embedded Linux processor. The processor has multiple tasks to handle on a single core, some of these tasks are even blocking all other processes for around 1ms. So it seems to me that it is important that the data_callback() function always writes enough frames to pOutput such that those 1ms interruptions do not cause any glitches.

So I started looking into the frameCount parameter, according to the documentation this parameter defines how many frames can be written to pOutput. I noticed that the size of the frameCount parameter differs per audiocard that I am using so I thought it had something to do with the actual buffer that the hardware supports, when checking the buffer size of my soundcards however I notice that they are in fact way larger then the frameCount parameter.

This brings me to my question: where and how is the value of the frameCount parameter defined and is it possible to enlarge its value?

Thank you in advance 🙏

[mackron]

It's controlled by the device config via the periodSizeInFrames/Milliseconds member. By default it'll be approximately 10ms, but the exact size is determined by the backend which would explain why it differs between physical devices. Setting the period size explicitly in the device config should make it consistent.