Daphile/MPD : Bit Perfect, véritablement ?

[0000]

J'ai aussi cette variation :

DAC Adaptive (Non-Asynchrone) (entrée usb de FX audio D802) :

Code :

$ cat /proc/asound/FXAUDIOD802/stream0
FX-AUDIO FX-AUDIO-D-802 at usb-0000:00:14.0-4, full speed : USB Audio

Playback:
 Status: Running
   Interface = 1
   Altset = 1
   Packet Size = 224
   Momentary freq = 44100 Hz (0x2c.199a)
 Interface 1
   Altset 1
   Format: S16_LE
   Channels: 2
   Endpoint: 4 OUT (ADAPTIVE)
   Rates: 44100, 48000, 88200, 96000, 176400, 192000
 Interface 1
   Altset 2
   Format: S24_3LE
   Channels: 2
   Endpoint: 4 OUT (ADAPTIVE)
   Rates: 44100, 48000, 88200, 96000

Code :

$ cat /proc/asound/FXAUDIOD802/stream0
FX-AUDIO FX-AUDIO-D-802 at usb-0000:00:14.0-4, full speed : USB Audio

Playback:
 Status: Running
   Interface = 1
   Altset = 2
   Packet Size = 576
   Momentary freq = 96000 Hz (0x60.0000)
 Interface 1
   Altset 1
   Format: S16_LE
   Channels: 2
   Endpoint: 4 OUT (ADAPTIVE)
   Rates: 44100, 48000, 88200, 96000, 176400, 192000
 Interface 1
   Altset 2
   Format: S24_3LE
   Channels: 2
   Endpoint: 4 OUT (ADAPTIVE)
   Rates: 44100, 48000, 88200, 96000

DAC (interface HiFace 2) Asynchrone :

Code :

$ cat /proc/asound/UAC2/stream0
M2Tech hiFaceTWO UAC2 at usb-orion-ehci.0-1, high speed : USB Audio

Playback:
 Status: Running
   Interface = 1
   Altset = 2
   Packet Size = 28
   Momentary freq = 44102 Hz (0x5.8340)
   Feedback Format = 16.16
 Interface 1
   Altset 1
   Format: S32_LE
   Channels: 2
   Endpoint: 1 OUT (ASYNC)
   Rates: 44100, 48000, 88200, 96000, 176400, 192000
   Data packet interval: 125 us
 Interface 1
   Altset 2
   Format: S16_LE
   Channels: 2
   Endpoint: 1 OUT (ASYNC)
   Rates: 44100, 48000, 88200, 96000, 176400, 192000
   Data packet interval: 125 us

Code :

$ cat /proc/asound/UAC2/stream0
M2Tech hiFaceTWO UAC2 at usb-orion-ehci.0-1, high speed : USB Audio

Playback:
 Status: Running
   Interface = 1
   Altset = 1
   Packet Size = 120
   Momentary freq = 96004 Hz (0xc.0020)
   Feedback Format = 16.16
 Interface 1
   Altset 1
   Format: S32_LE
   Channels: 2
   Endpoint: 1 OUT (ASYNC)
   Rates: 44100, 48000, 88200, 96000, 176400, 192000
   Data packet interval: 125 us
 Interface 1
   Altset 2
   Format: S16_LE
   Channels: 2
   Endpoint: 1 OUT (ASYNC)
   Rates: 44100, 48000, 88200, 96000, 176400, 192000
   Data packet interval: 125 us

Je ne suis pas capable de te donner une explication. Mais j'ai trouvé ça :

Citation :With UAC1 device in isochronous adaptive mode, the DAC and computer negotiate a shared sample rate, mostly using a PLL mechanism. The
Momentary freq
value shows the result of that negotation which should be equal to that of the file being played.
With USB Audio Class 2 in isochronous asynchronous mode, like new Pink Faun DAC2 with an Amanero(?) supports, every
125us
the DAC tells the computer how many SPDIF-packets it should sent in one USB Request Block (URB).
In the output you can actually see that happening when playing high resolution files; the
Momentary freq
flips from
192.000Hz
to something like
191.999Hz
and back again.

( https://lacocina.nl/detect-alsa-output-capabilities )

Edit : le player est MPD.