From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre-Louis Bossart Subject: Re: [alsa-devel] [PATCH v2 5/6] sound/usb: pcm changes to use media token api Date: Wed, 22 Oct 2014 14:26:41 -0500 Message-ID: <544804F1.7090606@linux.intel.com> References: <543FB374.8020604@metafoo.de> <543FC3CD.8050805@osg.samsung.com> <543FD1EC.5010206@osg.samsung.com> <543FD892.6010209@osg.samsung.com> <54467EFB.7050800@xs4all.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Devin Heitmueller , Takashi Iwai Cc: alsa-devel@alsa-project.org, Lars-Peter Clausen , Linux Media Mailing List , Greg Kroah-Hartman , "ramakrmu@cisco.com" , Shuah Khan , Hans Verkuil , Sander Eikelenboom , prabhakar.csengg@gmail.com, Antti Palosaari , Laurent Pinchart , "sakari.ailus@linux.intel.com" , Andrew Morton , Tim Gardner , "olebowle@gmx.com" , Linux Kernel , Mauro Carvalho Chehab List-Id: alsa-devel@alsa-project.org On 10/21/14, 11:08 AM, Devin Heitmueller wrote: >> Sorry, I'm not convinced by that. If the device has to be controlled >> exclusively, the right position is the open/close. Otherwise, the >> program cannot know when it becomes inaccessible out of sudden during >> its operation. > > I can say that I've definitely seen cases where if you configure a > device as the "default" capture device in PulseAudio, then pulse will > continue to capture from it even if you're not actively capturing the > audio from pulse. I only spotted this because I had a USB analyzer on > the device and was dumbfounded when the ISOC packets kept arriving > even after I had closed VLC. this seems like a feature, not a bug. PulseAudio starts streaming before clients push any data and likewise keeps sources active even after for some time after clients stop recording. Closing VLC in your example doesn't immediately close the ALSA device. look for module-suspend-on-idle in your default.pa config file. I also agree that the open/close of the alsa device is the only way to control exclusion. -Pierre