From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lennart Poettering Subject: Re: What does snd_pcm_delay() actually return? Date: Fri, 13 Jun 2008 16:29:23 +0200 Message-ID: <20080613142923.GC21255@tango.0pointer.de> References: <20080609190225.GA4534@tango.0pointer.de> <20080612205225.GB20818@tango.0pointer.de> <20080613135128.GA21255@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 9540D103817 for ; Fri, 13 Jun 2008 16:29:23 +0200 (CEST) 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-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org On Fri, 13.06.08 15:55, Jaroslav Kysela (perex@perex.cz) wrote: > On Fri, 13 Jun 2008, Lennart Poettering wrote: > > > c) snd_pcm_hw_params_get_buffer_size() - snd_pcm_update_avail() > > returns the fill level, but only works on mmap. > > snd_pcm_update_avail() works (or should work) also for standard r/w > ops. Ok, so it's just the documentation that needs fixing? Quoting: "Using of this function is useless for the standard read/write operations. Use it only for mmap access." > > d) The snd_pcm_hw_params_get_fifo_size() was supposed to return the > > 'difference' between a) and c), but was never actually used > > for that. > > Nope. It's maximum latency added by an extra fifo/queue (it does not > depend if it's hw or sw fifo). For variable fifo size, we need to extend > API. Ok, so it's an upper ceiling for the difference between a) and c), right? Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net ICQ# 11060553 http://0pointer.net/lennart/ GnuPG 0x1A015CC4