From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Longerbeam Subject: Re: non-interleaved mode Date: Wed, 11 Jul 2007 11:12:49 -0700 Message-ID: <46951DA1.9000500@embeddedalley.com> References: <4693CB01.5060804@embeddedalley.com> <20070711091324.43424685.alsauser@pragmasoft.com> <469503F0.80706@embeddedalley.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from smtp110.biz.mail.mud.yahoo.com (smtp110.biz.mail.mud.yahoo.com [68.142.201.179]) by alsa0.perex.cz (Postfix) with SMTP id BCB761038FD for ; Wed, 11 Jul 2007 20:12:57 +0200 (CEST) In-Reply-To: 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: Jaroslav Kysela Cc: Takashi Iwai , "J. Scott Merritt" , ALSA development List-Id: alsa-devel@alsa-project.org Jaroslav Kysela wrote: > On Wed, 11 Jul 2007, Steve Longerbeam wrote: > > >> Last night I ran an experiment. I created a 16-bit stereo .wav file >> with all left samples = 0x5555, and all right samples = 0xAAAA. I then >> played the .wav using aplay, and just before trigger start in my driver >> I searched the DMA buffer for the first occurrence of 0xAAAA. The right >> samples didn't start until exactly half-way through the entire DMA buffer! >> > > Yes, it's the right non-interleaved behaviour. You can imagine this layout > as separate "mono" ring buffers for each channels - see > snd_pcm_lib_ioctl_channel_info() in pcm_lib.c . Driver might modify > info->offset if required (see hdsp.c driver for example). > thanks, that cleared everything up for me. Steve