From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: emu10k1 latency / capture period Date: Tue, 22 Jun 2004 13:13:09 +0200 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: References: <1087416890.25102.21.camel@debian> <1087704381.805.20.camel@debian> <1087849237.8161.38.camel@debian> Mime-Version: 1.0 (generated by SEMI 1.14.5 - "Awara-Onsen") Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: <1087849237.8161.38.camel@debian> Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Lee Revell Cc: Alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org At Mon, 21 Jun 2004 16:20:38 -0400, Lee Revell wrote: > > The capture will be driven by the playback interrupts (I think > EFX_BUFFER(HALF)FULL). This would look very similar to the > interrupt handler example #2 in your ALSA driver guide, which > uses timer interrupts to drive the capture/playback, except > that for playback, in addition to calling snd_pcm_period_elapsed() > on the playback substream, we also maintain a pointer to the > corresponding *capture* substream, and call snd_pcm_period_elapsed() > on it, manually tracking the frames processed in the same way the timer > interrupt example does. Even if we ignore the capture interrupts and use an additional interrupt source (e.g. an extra playback stream), the size of capture buffer still must follow the restriction. That is, the minimal capture buffer size is still 384 x 2 bytes, although the period size can be set independently to smaller than 384 bytes. Takashi ------------------------------------------------------- This SF.Net email sponsored by Black Hat Briefings & Training. Attend Black Hat Briefings & Training, Las Vegas July 24-29 - digital self defense, top technical experts, no vendor pitches, unmatched networking opportunities. Visit www.blackhat.com