From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Gruber Subject: Full duplex ALSA-plugin Date: Tue, 10 Jul 2012 16:28:33 +0200 Message-ID: <4FFC3C11.4020600@voiceinterconnect.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from dd14716.kasserver.com (dd14716.kasserver.com [85.13.136.34]) by alsa0.perex.cz (Postfix) with ESMTP id B00362437B for ; Tue, 10 Jul 2012 16:24:42 +0200 (CEST) Received: from server-a.vic.site (146-52-60-185-dynip.superkabel.de [146.52.60.185]) by dd14716.kasserver.com (Postfix) with ESMTPSA id 3B21115CC02A for ; Tue, 10 Jul 2012 16:24:42 +0200 (CEST) Received: from kepler.vic.site ([192.168.13.149]) by server-a.vic.site with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from ) id 1SobMn-0003Ra-9I for alsa-devel@alsa-project.org; Tue, 10 Jul 2012 16:24:41 +0200 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org 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