[PROBLEM] Loopback function forcing 44.1kHz playback - Expected behavior or limitation?

[thestreamdigger]

Hello,

I've been using the loopback function to work with CAVA and achieve some beautiful visualizations on physical LED devices. However, I've encountered an issue where enabling loopback causes all playback output to be converted to 44.1kHz. I'm wondering if this is expected behavior?
No specific frequency settings are defined in the CAVA configuration file and no resampling are enabled.
This could potentially be a limitation of ALSA, but since the loopback function is integrated into moOde, I'm inquiring here to see if there's anything that can be done to play music at higher frequencies while keeping loopback enabled.

Questions:
1) Is the 44.1kHz conversion when using loopback an intentional design choice or a known limitation?
2) Are there any settings or workarounds to maintain higher sample rates (e.g., 96kHz, 192kHz) while using loopback?
If this is a limitation, is it on moOde's (ALSA) side or CAVA's side?

I appreciate any insights or solutions the community can provide.
Thank you for your help!

[Tim Curtis]

CAVA prolly only supports 44.1K.

ALSA loopback in our build supports up to 384K.  Here's an example.

Code:

# Boss DAC (card2)
pi@moode9:~ $ cat /proc/asound/card2/pcm0p/sub0/hw_params
access: MMAP_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 384000 (768000/2)
period_size: 32768
buffer_size: 131072

# Loopback (card3)
pi@moode9:~ $ cat /proc/asound/card3/pcm0p/sub0/hw_params
access: MMAP_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 384000 (384000/1)
period_size: 32768
buffer_size: 131072

pi@moode9:~ $ aplay -l
[size=small][font=Monaco, Consolas, Courier, monospace]**** List of PLAYBACK Hardware Devices ****[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]card 0: vc4hdmi0 [vc4-hdmi-0], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0][/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevices: 1/1[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #0: subdevice #0[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]card 1: vc4hdmi1 [vc4-hdmi-1], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0][/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevices: 1/1[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #0: subdevice #0[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]card 2: BossDAC [BossDAC], device 0: Boss DAC HiFi [Master] pcm512x-hifi-0 [Boss DAC HiFi [Master] pcm512x-hifi-0][/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevices: 0/1[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #0: subdevice #0[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]card 3: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM][/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevices: 7/8[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #0: subdevice #0[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #1: subdevice #1[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #2: subdevice #2[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #3: subdevice #3[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #4: subdevice #4[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #5: subdevice #5[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #6: subdevice #6[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #7: subdevice #7[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]card 3: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM][/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevices: 8/8[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #0: subdevice #0[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #1: subdevice #1[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #2: subdevice #2[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #3: subdevice #3[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #4: subdevice #4[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #5: subdevice #5[/font][/size]
[size=small][font=Monaco, Consolas, Courier, monospace]  Subdevice #6: subdevice #6[/font][/size]
 Subdevice #7: subdevice #7