From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: ring buffer pointer accuracy. Date: Mon, 14 Jul 2003 16:29:17 +0200 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: References: <3F0D86D0.6040905@superbug.demon.co.uk> <20030711172808.694df05b.pochini@shiny.it> Mime-Version: 1.0 (generated by SEMI 1.14.4 - "Hosorogi") Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: <20030711172808.694df05b.pochini@shiny.it> Errors-To: alsa-devel-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: To: Giuliano Pochini Cc: James Courtier-Dutton , alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org At Fri, 11 Jul 2003 17:28:08 +0200, Giuliano Pochini wrote: > > On Thu, 10 Jul 2003 16:31:28 +0100 > James Courtier-Dutton wrote: > > > Hi, > > > > When an application reads the "avail" or "delay" pcm values: - > > 1) how accurate are they? > > 2) does the accuracy depend on the sound card driver being used. > > Worst case accuracy is about one period AFAIK. It depends on the sound chip > because the low level driver reads the DMA pointer (or something) from some > hardware register or it can know the DMA pointer when it receives an interrupt > at the end of a period. yes. if the accuracy is in period size, at least it should work somehow. e.g. the time-slider of a player might not move so smooth but it must not be critical. Takashi ------------------------------------------------------- This SF.Net email sponsored by: Parasoft Error proof Web apps, automate testing & more. Download & eval WebKing and get a free book. www.parasoft.com/bulletproofapps1