Date: Fri, 13 Aug 2004 16:42:07 +0100 From: Peter Wood <peter@alastria.net> To: Mathew Kanner <mat@cnd.mcgill.ca> Cc: freebsd-chat@freebsd.org Subject: Re: FreeBSD pcm(4) latency (From write() to audible output) Message-ID: <411CE14F.3070509@alastria.net> In-Reply-To: <20040813151230.GB280@cnd.mcgill.ca> References: <411C9FE9.3000905@alastria.net> <20040813151230.GB280@cnd.mcgill.ca>
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> Freebsd-multimedia would be the right place. I think what you > want is a smaller block size. The SNDCTL_DSP_SETBLKSIZE should be the > right IOCTL to use, check out the oss programmers manual, I don't have > a link right now but google should find it pretty quick. Just to wrap this up here too: My problem was primarly due to the fragment sizes of buffers. I don't know what sizes are set as default but they're to big for my applications. I've found with the following it killed the delay to next to nothing (about 5ms by my working out). val = (2 << 16) | 9; ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &val); Thanks Mathew, Pete. -- Peter Wood BSc (Hons) :: <peter@alastria.net> :: Tel +44 7974 799440
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