On Tue, Aug 29, 2023 at 8:37 AM Jaroslav Kysela perex@perex.cz wrote:
The modifiers may define extra PCM streams in the standard Value section - you can use CapturePCM value for the modifier like "Echo Reference". Modifiers may alter the characteristics of the original UCM device stream (using command sequences), too.
Thanks for the clarification, that indeed is where the assumption I think for most of us is not as clear. I would have never thought a modifier would carry a PCM.
I will trigger some work internally to convert our value to the modifier syntax.
Curtis
Modifiers are an extra layer on top of devices. I don't think that we have any default relation between the modifier PCM device and the original PCM device (from the UCM device definition). A new value to describe this (like "ReplacePlaybackPCM 1") may be introduced. Another issue is when multiple modifiers with this description are active - they conflict, so it should be described somewhere, too. Perhaps, "ConflictingModifier" array may be added to API. But those extensions are not required for the "Echo Reference" modifier.
Jaroslav-- Jaroslav Kysela perex@perex.cz Linux Sound Maintainer; ALSA Project; Red Hat, Inc.