Testing an audio DAC

Hardware Librem 5
41

Ok then that is meaning that PCM it not FOR Real Bit Perfect mode as it can be manipulate/degradable. But as looks like PCM or any still can be FORCED to be unmanipulate on path way to dac with a dedicated configs, thats is what i want by keeping volumen and rest data intact to the dac, then the amplifier get the control of volumen and dac take control of data sound.
If i remember well alsa have a option to disable volumen control but also 100% on software may be a real volumen track.

Kinda

Thank you.

:heart_eyes:

1 Like
42

I got Bit-Perfect on Gnu Librem 5 Crimson

purism@pureos:~/Music/SergioVargas$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: imxaudiohdmi [imx-audio-hdmi], device 0: i.MX HDMI i2s-hifi-0 [i.MX HDMI i2s-hifi-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: L5 [Librem 5], device 0: 308b0000.sai-wm8962 wm8962-0 [308b0000.sai-wm8962 wm8962-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: Modem [Modem], device 0: 30030000.sai-bm818 bm818-0 [30030000.sai-bm818 bm818-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 3: H256 [Henry Audio DA 256], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
purism@pureos:~/Music/SergioVargas$ mpv --ao=alsa --audio-device=alsa/hw:3,0 --audio-exclusive=yes LasMujeres.wav 
 (+) Audio --aid=1 (pcm_s16le 2ch 44100Hz)
AO: [alsa] 44100Hz stereo 2ch s16
A: 00:01:40 / 00:04:11 (40%)

Thanks: The Best of the Best: s.krzyszkowiak

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43

It’s unusal to see someone be obsessed with some form of “bit perfect” performance while also being okay with lossy audio source formats.

mpv has (or at least used to have) an “always on” software volume control also, it may be that setting it to 100% disables the feature, but may be it doesn’t.

mpv’s ALSA driver ignores the --audio-exclusive option, it doesn’t need it, if you access an alsa/hw:* device you will get an exclusive lock on the device without any need to explicitly set an option for it.

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44

Bit-Perfect mean that the track/source it is not being distorted, manipulated on the route to dac, so it can be a MP3 or PCM. However MP3 or DSP are UNBit-Perfect naturally. But yes mp3 not make sense all.

I think you are right, however i did: --audio-exclusive=yes to force it. I think that only --audio-exclusive=yes do the trick without --ao=alsa --audio-device=alsa/hw:3,0

I would like a Mobile Music player supporting Bit-Pure Mode(bit-perfect). @dos

1 Like
45

Without --ao=alsa --audio-device=alsa/hw:3,0 mpv will play through pulseaudio which also ignores the --audio-exclusive option, additionally pulseaudio may resample the signal.

Try entering… mpv --audio-exclusive=yes LasMujeres.wav and while playing back, go to sound settings and run the speaker test, you’ll probably find the “left”/”right” audio of the speaker test playing back simultaneously with your .wav file (i.e. no exclusivity).

Similarly, from a terminal window enter mpv --ao=alsa --audio-device=alsa/hw:3,0 LasMujeres.wav then open a second terminal window and enter the same command, you should find the second command will fail with an error regarding being unable to open the output device (i.e. exclusivity without explicity requesting it).

You just need a music player that provides a mechanism to set an ALSA device as output, whether such a thing exists with a UI that’s useable on mobile currently, I do not know.

For what it’s worth, I use cmus as my everyday music player, it’s terminal based, not the easiest to use on the Librem 5 but also not the worst. For critical listening, although not designed to be a music player application, I’m currently using SoX_ng, not much different from the original so far but it has implemented support for DSD.

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