More > JRiver Media Center 23 for Linux
Unable to play to snd-aloop output device
mattkhan:
--- Quote from: bob on February 22, 2018, 04:28:03 pm ---It depends on the setting of the audio advanced option "Auto configure on playback failure". It will guess a sample rate if playback fails.
Best to use DSP studio to set the rate. The important thing to know is that plughw as a default implies using ALSA resampling which we don't allow.
--- End quote ---
OK. ALSA devices have confused me for many many years but I'll ask anyway :) Any idea why aplay works to same device?
bob:
--- Quote from: mattkhan on February 22, 2018, 04:52:11 pm ---OK. ALSA devices have confused me for many many years but I'll ask anyway :) Any idea why aplay works to same device?
--- End quote ---
Because it's not disabling re-sampling when opening the device.
It looks to me from what you've posted that the native sample rate of that device is 44.1k.
mattkhan:
--- Quote from: bob on February 23, 2018, 08:57:17 am ---Because it's not disabling re-sampling when opening the device.
It looks to me from what you've posted that the native sample rate of that device is 44.1k.
--- End quote ---
I don't think that's true
for example if I do this in one terminal
--- Code: ---$ aplay -D hw:CARD=Loopback,DEV=0 --disable-resample Sine_1000.wav
Playing WAVE 'Sine_1000.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
--- End code ---
then in another one
--- Code: ---$ cat /proc/asound/card2/pcm0p/sub0/hw_params
access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 48000 (48000/1)
period_size: 6000
buffer_size: 24000
--- End code ---
I don't see any evidence, apart from in MC, that this is a 44.1kHz device
actually now I try this again I see alsacap reports
--- Code: ---..32 channels, sampling rates 8000, 11025, 16000, 22050, 32000, 44100, 48000, 88200, 96000, 176400, 192000 Hz
--- End code ---
no idea what is going on there, anyway at least I now know how to work out how MC sees the device capabilities. Thanks.
bob:
--- Quote from: mattkhan on February 23, 2018, 09:39:40 am ---I don't think that's true
for example if I do this in one terminal
--- Code: ---$ aplay -D hw:CARD=Loopback,DEV=0 --disable-resample Sine_1000.wav
Playing WAVE 'Sine_1000.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
--- End code ---
then in another one
--- Code: ---$ cat /proc/asound/card2/pcm0p/sub0/hw_params
access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 48000 (48000/1)
period_size: 6000
buffer_size: 24000
--- End code ---
I don't see any evidence, apart from in MC, that this is a 44.1kHz device
actually now I try this again I see alsacap reports
--- Code: ---..32 channels, sampling rates 8000, 11025, 16000, 22050, 32000, 44100, 48000, 88200, 96000, 176400, 192000 Hz
--- End code ---
no idea what is going on there, anyway at least I now know how to work out how MC sees the device capabilities. Thanks.
--- End quote ---
MC simply asks ALSA what the suggestions are for opening the devices. That's where the list of audio devices in MC comes from.
It starts with S32_LE and works it's way down the format list until one is successful when opening the device (auto mode) which you can override by specifying a format.
Sets the period and buffer times (perhaps you need to make those smaller)?
Uses the sample rate of the file when opening the device unless DSP studio is specifying something different and also disables device resampling. It's pretty straightforward.
I don't know why your loopback device shows up twice with different sample rates.
I'm suspicious that aplay with the sample rate disable flag isn't working as advertised on the device you are choosing.
mattkhan:
--- Quote from: bob on February 23, 2018, 09:52:47 am ---I'm suspicious that aplay with the sample rate disable flag isn't working as advertised on the device you are choosing.
--- End quote ---
not sure how to tell if that is happening, I guess I could play and record a dirac pulse and see if it comes out untouched
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