Open output devices with more channels than the plugin #56

PepperBoy commented 2026年06月26日 22:51:03 +02:00

The standalone cpal backend only accepted output configs whose channel count exactly matched the plugin's. Interfaces with a high channel count (e.g. a MOTU UltraLite) don't advertise a stereo config, so a stereo plugin couldn't open them.

This change accepts configs with at least the plugin's channel count and picks the smallest. The plugin's channels are written to the device's first N outputs and the remaining channels are padded with zeros.

Tested on a MOTU UltraLite-mk5 (opens at 22 channels, audio on outputs 1–2) and built-in 2-channel output.

Output always maps to the device's first N channels. A configurable channel offset could be added later.

The standalone cpal backend only accepted output configs whose channel count exactly matched the plugin's. Interfaces with a high channel count (e.g. a MOTU UltraLite) don't advertise a stereo config, so a stereo plugin couldn't open them. This change accepts configs with at least the plugin's channel count and picks the smallest. The plugin's channels are written to the device's first N outputs and the remaining channels are padded with zeros. Tested on a MOTU UltraLite-mk5 (opens at 22 channels, audio on outputs 1–2) and built-in 2-channel output. Output always maps to the device's first N channels. A configurable channel offset could be added later.

BillyDM commented 2026年06月27日 00:47:01 +02:00

Ideally we should also support interfaces with less output channels than the plugin (i.e. for plugins with multiple outputs or testing and ambisonic plugin on a stereo system).

Ideally we should also support interfaces with less output channels than the plugin (i.e. for plugins with multiple outputs or testing and ambisonic plugin on a stereo system).

BillyDM commented 2026年06月29日 19:15:56 +02:00

Thanks!

Thanks!