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

[Joakim Tjernlund]

On Tue, 2017-09-05 at 19:25 +0200, Joakim Tjernlund wrote:
> 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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