[LAD] [alsa-devel] Using loopback card to Connect GSM two way call to the real sound card UDA1345TS

Clemens Ladisch clemens at ladisch.de
Mon Mar 9 08:09:16 UTC 2015

Srinivasan S wrote:
> Could you please provide any inputs w.r.t the loopback card using
> snd-aloop & alsaloop, how this loopback card can be used to connect
> the GSM two way call simultanoeusly to the UDA1345TS codec on MCASP0
> of the am335x (UDA1345TS ie., real sound card)

snd-aloop creates a virtual sound card; it is not used with a real sound

> The codec has two output channels VOUTL, VOUTR & two input channels VINL , VINR
> With this am able to achieve only one way call at a time by running
> only one application at a time

To allow a capture device to be shared, you need to use dsnoop.  Your
asound.conf already does this.

To allow a playback device to be shared, you need to use dshare or dmix.
(dshare allows to use _different_ channels; dmix allows mixing multiple
sources into the same channels.)  Your asound.conf does not do this; it
uses "hw" instead.


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