[alsa-devel] Different audio sample rate between in and out(44100 Hz resp. 44100 Hz)

Joakim Tjernlund Joakim.Tjernlund at infinera.com
Tue Sep 5 19:25:57 CEST 2017


When starting a audio chat I often have problems with my microphon and recenly I
found that the sample rate is different for in and out:
# > cat /proc/asound/card1/stream0
Logitech Inc Logitech Stereo H650e at usb-0000:00:1d.0-1.7, full speed : USB Audio

Playback:
  Status: Running
    Interface = 2
    Altset = 1
    Packet Size = 192
    Momentary freq = 48000 Hz (0x30.0000)
  Interface 2
    Altset 1
    Format: S16_LE
    Channels: 2
    Endpoint: 1 OUT (ADAPTIVE)
    Rates: 8000, 16000, 24000, 32000, 44100, 48000

Capture:
  Status: Running
    Interface = 1
    Altset = 1
    Packet Size = 200
    Momentary freq = 44100 Hz (0x2c.199a)
  Interface 1
    Altset 1
    Format: S16_LE
    Channels: 2
    Endpoint: 1 IN (ASYNC)
    Rates: 8000, 16000, 24000, 32000, 44100, 48000

This seems odd to me. Adding some debug to kernel I see:
[  129.858365] usb 1-2: 1:1: setting freq 44100 to ep 0x81
[  129.860514] usb 1-2: 1:1: setting freq 44100 to ep 0x81
[  131.884314] usb 1-2: 2:1: setting freq 44100 to ep 0x1
[  131.886567] usb 1-2: 2:1: setting freq 44100 to ep 0x1
[  131.898714] usb 1-2: 2:1: setting freq 48000 to ep 0x1
[  131.900847] usb 1-2: 2:1: setting freq 48000 to ep 0x1


Is this expected or should I try make both the same?

 Jocke


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