Date: Fri, 05 Apr 2002 18:44:26 +0000 From: "Matthew Hanson" <[EMAIL PROTECTED]> Subject: Re: AW: [LIB] recording audio? (danger technical)
>Date: Thu, 28 Mar 2002 09:20:37 >From: "neil barnes" <[EMAIL PROTECTED]> > >>This guy Karsten Krause posted to the list back in 1998 about his Roland >>SCP-55 sound card for his Lib that he seemed quite pleased with. I may >>just keep an eye out for one of those on EBay if I can't sort out these >>quiet little clicks in the recorded signal from the WavJammer.<< >Matt - are these clicks very regular? Have you looked at them with >CoolEditPro or similar? Are they recorded artifacs or replay artifacts?< I had deleted all of my original test files. Giving it a try again, I find it's very hard to find the exact spot where the clicking appears in the audio wave shape. It's always easy to edit out clicks that appear as obvious spikes in the wave shape with one of the various audio editing tools. But there are no obvious spikes that I can find in these files. Of course it's easier for me on my Atlhon 800 system out in CA with SoundForge installed. I'm not very used to using CoolEdit Pro on a Lib. But these are definately recorded artifacts. I can select the portion of the recorded signal where a click can be heard, and replaying the slection results in the same click being heard at the same point all the time, so I'd think that this would mean that it's not a replay artifact. They are random clicks, and don't appear at regular intervals as far as I can tell. They vary from 2-15 seconds apart. I actually got a bit better recorded signal using my Toshiba 6.4GB HDD, but there was still a significant number of clicks. The specs for the Hitachi 20GB HDD show a significatly slower internal transfer rate than the Toshiba: Hitachi DK23BA-20 20GB HDD Interface Transfer Rate: Max. 66.6 MB/s (Ultra DMA 4) Max. 16.6 MB/s (PIO Mode 4, DMA 2) Toshiba MK6411MAT 6.4GB HDD Data Transfer Rate: Internal 86.4 - 153.3Mb/s Of course I confess I don't know much about such specs. Whether this is an indication that the Toshiba is working faster than the Hitachi overall when all the other specs are taken into consideration, I can't say. But again, I was able to record a reasonably clean signal back in '96 with my P100 Tyan MB based system w/16 MB RAM, and a 1GB Quantum HDD. Though if that that Quantum spun faster than the 4200 RPM these 2.5" drives manage, I can't say. However it seems that quite a few people have said that they've managed to record clean audio with their Libbys. Hmmmm.... Shmatt >A major problem with sound and windows is that the hardware to >record/replay sound relies on DMA transfers to get the data into/out of >ram. There are restrictions on the hardware (it has to be in the first 16M >of memory, it can't cross a 0x000 boundary etc) which don't tie in well >with windows - windows wants to decouple physical memory from logical >memory. There are libraries which do varying degrees of damage to >utilisation rates as they try to present a decoupled view (the X-audio >libraries)< > >You may find it necessary to drop into dos mode and do your recording >there, if only to avoid the overhead and context switching. In a worst >case, it's possible that the OS is reading bits one at a time :)< > >If you want to write code, I have the reference manuals for the >soundblaster chipsets - though that may not be effective for your system.< > >Neil< _________________________________________________________________ MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide.aspx ************************************************************** http://libretto.basiclink.com - Libretto mailing list http://www.silverace.com/libretto/ - Archives -------TO UNSUBSCRIBE------- Reply to any of the list messages. The reply mail should be addressed to: [EMAIL PROTECTED] - Then replace any text on the message's subject line: cmd:unsubscribe --------TO UNSUBSCRIBE DIGEST------ Do above but with this on subject line: cmd:unsubscribe digest **************************************************************
