From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaroslav Kysela Subject: Re: PulseAudio and softvol Date: Wed, 15 May 2013 12:26:51 +0200 Message-ID: <519362EB.7050603@perex.cz> References: <1368611744.6590.8.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail1.perex.cz (mail1.perex.cz [77.48.224.245]) by alsa0.perex.cz (Postfix) with ESMTP id 51BAF2610C4 for ; Wed, 15 May 2013 12:26:53 +0200 (CEST) In-Reply-To: <1368611744.6590.8.camel@localhost> 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: Arun Raghavan Cc: alsa-devel@alsa-project.org, pulseaudio-discuss@lists.freedesktop.org List-Id: alsa-devel@alsa-project.org Date 15.5.2013 11:55, Arun Raghavan wrote: > Hello, > A number of users have intermittently(?) been hitting a crash in > alsa-lib 1.0.27 [1, 2] related to the softvol plugin. I'm not able to > reproduce this reliably, so can't find an easy way to debug/fix. The problem is that the offsets are not in sync in this case [1]: src_offset = 38560 dst_offset = 38568 frames = 16374 Could you reproduce this bug in any way? At least snd_pcm_dump() before the failing snd_pcm_mmap_commit() call might help to determine what was the status before the assert() was entered. > However, this raises a tangential question - why do we need softvol to > be plugged for 'front' at all? David explained to me that this is to > guarantee the existence of a PCM control. Perhaps I don't fully > understand this, because I'm unconvinced by the reason. Could someone > explain/refute? > > This is especially bad for us, from PulseAudio's perspective, because we > aren't getting a zero-copy path. If the softvol is set to 0dB (no attenuation or gain), then the ring buffer pointers are moved without any sample processing, so the zero-copy functionality is kept. Jaroslav > > Cheers, > Arun > > [1] https://bugzilla.redhat.com/show_bug.cgi?id=953352 > [2] https://bugs.freedesktop.org/show_bug.cgi?id=64299 -- Jaroslav Kysela Linux Kernel Sound Maintainer ALSA Project; Red Hat, Inc.