Resample only the main output (not the tracks)

[inoto]

Background:
I like to keep my sound card at 48k everywhere, because this way I can use all audio programs at once.
But sometimes I need to work on a 44.1k project in Reaper. If I keep the audio device at 48k, all the content in Reaper gets resampled to 48k on the fly, FX works at 48k and so on, regardless of the "project sample rate" setting.
This is undesirable, because it can change how things sound. Certain subtle phase relationships between tracks can change, some VSTs might sound differently and so on.

Idea:
Reaper would not resample the items and FX and synths to 48k in such cases, but keep them all working at the project sample rate (44.1k).
Only the main output, after it leaves the mixer, would be resampled to 48k, so that it matches the audio device SR.
This would also lower the CPU usage, because it's resampling just a single (usually stereo) stream, rather than all the individual content.

And I guess the most consistent/simple thing would be to treat the inputs the same way, and resample them on the fly.

[inoto]

Originally Posted by inoto

And I guess the most consistent/simple thing would be to treat the inputs the same way, and resample them on the fly.

Just to add: the recordings should be still recorded and stored on the drive at the audio device sample rate, but converted to the project SR on the fly for playback/processing -- like it happens now when an item's SR doesn't match the device SR. At least, I think this would probably be a sane default (but converting permanently is an option too).

And I wanted to ask: what's the advantage of the current behavior, which ignores the "Project sample rate" setting for real time playback/processing?
I'm not that familiar with Reaper yet, so maybe I missed something obvious.

With my proposal, you'd also be able to use a very high SR in a project, regardless of what your device supports. For instance, if you have an old plugin that aliases badly and you want to run it at 192kHz, you could do that, even if your audio device can only run at 44.1kHz. Currently, you can't -- well, you can only render at that SR, but not hear its effects in real-time.

And to inform the user when Reaper's output is being resampled to match the device SR, there could be a small indication in the top right corner, just like for the items on a track. Something like: