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 20:29:53 +0200 Message-ID: <20080613182953.GA1954@tango.0pointer.de> References: <20080609190225.GA4534@tango.0pointer.de> <20080612205225.GB20818@tango.0pointer.de> <20080613142526.GB21255@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 D384C24501 for ; Fri, 13 Jun 2008 20:29:53 +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 18:26, Takashi Iwai (tiwai@suse.de) wrote: > Wait, wait. Please don't mix up. The above doesn't imply anything > about the further implementation of usb-audio driver. What I > suggested is, instead of hiding two pointers (hw_ptr and curr_ptr) and > creating a complex API, simply expose them. > > Now, regarding the usb-driver. Honestly, I don't understand what you > want to do with an extra URB. > > As now, usb-audio driver handles as curr_ptr == hw_ptr. But, in > reality, curr_ptr = hw_ptr - samples_in_urbs. So, in the case > of USB-audio, hw_ptr is ahead of curr_ptr. (And the granularity is > samples_in_urbs). BTW: what's the relation between periods and URBs on usb-audio right now? I mean, the URBs should be exposed as periods to userspace, right? But they are not right now, are they? I mean, I can set all kinds of strange period settings for my USB device and I am pretty sure that this is not reflected in the URB size, or am I wrong? Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net ICQ# 11060553 http://0pointer.net/lennart/ GnuPG 0x1A015CC4