Date: Fri, 11 Dec 1998 12:29:12 -0600 (CST) From: Kevin Day <toasty@home.dragondata.com> To: richard@pegasus.com (Richard Foulk) Cc: pb@wave.campus.luth.se, freebsd-hardware@FreeBSD.ORG Subject: Re: sane sound cards? Message-ID: <199812111829.MAA05766@home.dragondata.com> In-Reply-To: <199812111755.HAA09539@pegasus.com> from Richard Foulk at "Dec 11, 1998 7:55:26 am"
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> } >All of the cards I've checked into appear to fail because there is no data > } >buffer on the card. At least not large enough to handle 44.1kHz stereo. > } >My guess is that somewhere between 16K and 64K bytes of buffer should be > } >sufficient. > } > } Buffering is done with primary memory. Card only needs about 4K buffer. > } > > What do you mean by primary memory? If it ain't on the card it's not > what I want. If it's not on the sound card a slow device elsewhere on > the system will be able to starve the sound card. Most, if not all sound cards use DMA to pull sound out of the system ram and stream it in. You control the size of the buffer in software that you want to keep loaded off of the disk, and in an interrupt handler (that can't really get too lagged) you give it the next dma command and start loading the next block. If you're getting skipping/missing, it's because your system can't keep up or there are driver problems. I have an original Soundblaster 1.0 (giant ISA card) that has a 64 byte buffer, but can DMA. I'm able to play mp3's on it with ease. Look for IRQ conflicts, or try a different audio driver if possible. > A larger on-card buffer would make the problem go away. Not really. You're DMA'ing data from the system to the card, so that will never get interrupted with load. I don't know of any sound systems that have a bigger buffer, but I'm sure someone will correct me. :) Kevin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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