From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ricardo Neri Subject: Required/preferred multichannel order for ALSA Date: Thu, 26 Apr 2012 16:33:57 -0500 Message-ID: <4F99BF45.4020909@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from devils.ext.ti.com (devils.ext.ti.com [198.47.26.153]) by alsa0.perex.cz (Postfix) with ESMTP id 5427E10BC60 for ; Thu, 26 Apr 2012 23:34:01 +0200 (CEST) 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: Takashi Iwai Cc: "Castaneda Gonzalez, Axel" , alsa-devel , Ujfalusi , "Guiriec, Sebastien" , Peter@alsa-project.org, Liam Girdwood List-Id: alsa-devel@alsa-project.org Hi Takashi, list, I am implementing multichannel support for HDMI on Texas Instruments' OMAP4. I would like to know if ALSA mandates a specific channel order or has a preferred one. I tried to find some guidance in alsa-lib or in the alsa driver. All I could find is the order described in speaker-test: FL/FR/RL/RR/C/LFE/SL/SR. This order seems to be in use due to historical reasons [1]. It was also mentioned that an API to set/get the channel mapping was going to be implemented [2]; I tried to find it without success. As [1] and [2] are very old posts, I was wondering if the situation has changed. My question arises from the fact that HDMI audio uses the channel ordering defined in CEA-861 section 6.6.2, which is different from what speaker-test expects. This also different from the order that SMPTE 320M specifies. OMAP4 is able to alter the channel mapping, so I could match what ALSA expects if such required/preferred order exists. Thanks in advance for your comments. Ricardo [1].http://www.spinics.net/lists/alsa-devel/msg24444.html [2].http://www.spinics.net/lists/alsa-devel/msg24495.html