I was looking for information on writing an echo cancellation ALSA-plugin. So I studied the ALSA-plugin docs and also found several interesting threads in this mailing list. But what I found out, was quiet disillusioning.
If I understood the ALSA-plugin concept right, there is no possibility to write a plugin working on two streams, a playback and a record stream, simultaneously. One can only write a filter plugin, which works either on a playback stream or a record stream but not both. And there is no possibility to open a full duplex stream (consisting of playback and record) with snd_pcm_open().
Is there a reason, why full duplex streams are not implemented yet? Or is it planned in the future to implement this feature?
Regards, Christian