From mboxrd@z Thu Jan 1 00:00:00 1970 From: Craig McQueen Subject: Stale data at start of audio recording on Freescale i.MX28 EVK with SGTL5000 Date: Fri, 14 Nov 2014 09:41:56 +1100 Message-ID: <546533B4.90303@beamcommunications.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from APAC01-HK1-obe.outbound.protection.outlook.com (mail-hk1on0091.outbound.protection.outlook.com [134.170.140.91]) by alsa0.perex.cz (Postfix) with ESMTP id 8267F2661AE for ; Thu, 13 Nov 2014 23:42:07 +0100 (CET) List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: "alsa-devel@alsa-project.org" List-Id: alsa-devel@alsa-project.org I was testing the 3.14.19 kernel on Freescale i.MX28 EVK. Since then, I've retested and confirmed this also on 3.18-rc4 kernel. I am doing audio recordings through the SGTL5000 driver as such: arecord -D hw:0,1 -f s16 -c 2 -r 16000 -d 5 test.wav I'm finding that the first 400-500 ms of the saved data is actually stale data from the end of the previous recording. To see this, do the following: 1. Provide some test audio input in the LINE INPUT jack. E.g. a 100 Hz sine wave, or some music. 2. Record audio with e.g. arecord -D hw:0,1 -f s16 -c 2 -r 16000 -d 5 test1.wav 3. Change the test audio input, e.g. a 150 Hz sine wave, or some different music. 4. Record a new audio file with e.g. arecord -D hw:0,1 -f s16 -c 2 -r 16000 -d 5 test2.wav Observe that the first 400-500 ms of test2.wav contains stale data from the end of the previous recording. -- Craig McQueen