I am able to replicate the issue (at least the first part). When I play my arturia keylab keyboard through a scarlett focusrite interface, I normally set buffer size (which determines latency) to 128. When I start a music app playing through the same output (focusrite), it automatically changes the buffer size to another size, usually 1024 (as you saw). In one case (qobuz app) it changed it to 4096! In those cases, I couldn't set the buffer size back to 128 while the music was playing. When the music stopped, it remained at 1024 (or whatever large value) and did not automatically reset to 128. However, in every case, I was able to manually set it back to 128 without a problem (I didn't have the issue that dcbrow had where it couldn't easily be set back after the music stopped). This is running pianoteq 8.3.1.
I am pretty sure the problem is that to mix the two audio outputs (from pianoteq and the streaming app) it chooses the buffer size that can accommodate both apps. Pianoteq, being a professional app for musicians, is optimized to support very low latency and small buffer sizes. I imagine most music playing apps are not optimized this way, and may default to requiring a 1024 sample buffer size or more. For most purposes this is no problem.
I am not sure Modartt would call this a bug. You might argue that it should switch back to the original buffer size once the music stops, but it probably isn't always obvious that the stream has stopped--it may continue to send a silent signal or something? In any case it wouldn't solve your problem, which is to play both at once with low latency. The solution is to mix the signals together with an app that will let you control buffer size and output that, which is what Irmin suggested with AUM. That's a good solution--I have Logic Pro and that works as well. In fact I had never bumped into this issue because I would normally run pianoteq in Logic Pro if I wanted to mix in another sound source, to be able to control levels between them, and other effects. However this isn't a solution for streaming a backing track that you don't have a local file for. I imagine all the streaming services need the larger buffer sizes to ensure smooth streaming over wi-fi.
If someone knows a music app that can be set to output (or even stream) music with a buffer size of 128 or 256, it would be nice to know about it.
Last edited by sharpnine (05-08-2024 20:00)
