From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martijn Sipkema" Subject: Re: Fw: writing audiowerk driver (philips saa7146a), some questions Date: Fri, 31 May 2002 15:36:51 +0100 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: <000c01c208b0$a18fd720$0400a8c0@martijn> References: <001801c2088f$71693120$0400a8c0@martijn><003201c208a3$d8e06030$0400a8c0@martijn> Reply-To: "Martijn Sipkema" Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Errors-To: alsa-devel-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: To: Takashi Iwai Cc: alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org > there is a runtime instance for a pcm stream, and this holds the > informaton such as the current rate, channels, formats, etc. > there is no pitch parameter implemented in alsa, but this can be added > easily into the runtime instance, if inevitablly necessary. i don't think the audiowerk is the only card capable of varipitch, though most cards don't support it, but it is a nice feature and since alsa is supposed to be advanced... :) > alsa pcm engine invokes a timer interrupt to update the "tick", and > this tick is determined using the rate of the runtime instance. > if you change the rate value dynamically during playback, then the > tick interrupt will be wrongly scheduled, and leads to wrong detection > of under/overrun. shouldn't the driver detect under/overrun? would a soundcard with a bad dac (as in not accurate) also cause problems? --martijn _______________________________________________________________ Don't miss the 2002 Sprint PCS Application Developer's Conference August 25-28 in Las Vegas -- http://devcon.sprintpcs.com/adp/index.cfm