I am using Spotify Connect, and running a Topping E30 DAC via USB. The songs are at 44.1KHz 16bit, but I believe the output to the DAC is 44.1KHz 32bit, this is just padding out the bitrate with '0’s to support what the DAC is requesting? I was hoping to get ‘bitperfect’ output to my DAC.
I’ve looked at the spec sheet of the E30, and it does support PCM 16-32bit range. But not too sure if the output to the DAC is “upsampling” from 16bit to 32bit.
[cat /proc/asound/E30/stream0]
Playback:
Status: Running
Interface = 1
Altset = 1
Packet Size = 72
Momentary freq = 44105 Hz (0x5.8360)
Feedback Format = 16.16
Interface 1
Altset 1
Format: S32_LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
Data packet interval: 125 us
Interface 1
Altset 2
Format: S32_LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
Data packet interval: 125 us
Interface 1
Altset 3
Format: SPECIAL DSD_U32_BE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000, 352800, 384000, 705600, 768000
Data packet interval: 125 us
[cat /proc/asound/E30/pcm0p/sub0/hw_params]
access: MMAP_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 44100 (44100/1)
period_size: 5514
buffer_size: 22052
P.S what does MMAP_INTERLEAVED mean, can’t seem to find any information on it or RW_INTERLEAVED?