From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lennart Poettering Subject: Re: Disable conversions Date: Sun, 25 Nov 2007 21:41:32 +0100 Message-ID: <20071125204132.GA15151@tango.0pointer.de> References: <20071120005151.GA25276@tango.0pointer.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from tango.0pointer.de (tango.0pointer.de [85.214.72.216]) by alsa0.perex.cz (Postfix) with ESMTP id 79B2224614 for ; Sun, 25 Nov 2007 21:41:35 +0100 (CET) Content-Disposition: inline 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: ALSA Development Mailing List List-Id: alsa-devel@alsa-project.org On Wed, 21.11.07 12:40, Takashi Iwai (tiwai@suse.de) wrote: > At Tue, 20 Nov 2007 01:51:51 +0100, > Lennart Poettering wrote: > > > > 4) If I open an audio device with "plughw:" i can disable the software > > resampling that takes place via > > "snd_pcm_hw_params_get_rate_resample()". However, there is no > > equivalent for disabling the channel number adjustment or the > > sample format conversion. This would be very useful in PA however, > > since this would allow me to use only the parts of plughw I am > > interested in (softvol), and disable all the rest (resampling, > > conversion, channel remixing). > > Hmm.. It's a bit difficult to implement in a clean way. > For example, what would be the reason to disable softvol? Hmm, I think there's some kind of misunderstand here: softvol is the only part I am interested in to use. It's the resampling, the sample type conversion, and the channel map changing I want to disable. Right now, I can only disable the resampling, but the type conversion and channel conversion always stay enabled. Or did I miss something? > It's basically irrelevant with the PCM parameters. It's added just > because of lack of hardware volume controls. > > One idea I have is to make an API like > > snd_pcm_alias_plugin(src, dst); > > For example, > > snd_pcm_alias_plugin("softvol", "passthru"); > > would take passthru plugin instead of softvol plugin. > (Suppose passthru plugin as a simply pass-through plugin to its > slave.pcm) I am not sure if I understand what this would be useful for? Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net ICQ# 11060553 http://0pointer.net/lennart/ GnuPG 0x1A015CC4