Date: Sat, 06 Apr 2002 07:49:02 +0000
From: "Matthew Hanson" <[EMAIL PROTECTED]>
Subject: Re: AW: [LIB] recording audio? (danger technical)
>From: "neil barnes" <[EMAIL PROTECTED]>
>
>
>>Date: Fri, 05 Apr 2002 18:44:26 +0000
>>From: "Matthew Hanson" <[EMAIL PROTECTED]>
>>Subject: Re: AW: [LIB] recording audio? (danger technical)
>>
>
>>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.<<
>This sounds then as if individual or small numbers of samples are being
>dropped. Remind me again how you're getting the audio into the machine?<
I've been feeding this New Media WavJammer sound card with the output of my
EXP CD-ROM both plugged into the Lib, and separately powered by AA batteries
and using it like a music CD player. I've also used the headphone output
from the HP M820E drive, and would you believe, got it to be controlled with
MusicMatch v4.0 on the L70 while recording with CoolEdit Pro. I thought
that by pushing the system resources, I might see an increase in the number
of clicks, or other distortion of some kind. But the resulting recorded
signal is pretty much the exact same thing I get from recording from the EXP
drive on batteries.
Funny thing though, when I start recording, the frequency of initial
clicking occurrences is relatively high within the first 5-8 seconds, and
then decreases dramatically thereafter. I could probably get the recording
by an average group of non-critical listeners sitting around sipping
Margaritas, and competing with the music volume, as is so often the case in
these settings. 8-0
>>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
>>
>
>Are you comparing apples with oranges here?
Well... whatever they squeeze into those Margaritas! Actually I mis-quoted
the Hitachi specs there which should have been:
Hitachi DK23BA-20 20GB HDD
Internal Transfer Rate 14.1 to 24.8 MB/s
>The only spec you care about is the PIO mode 4, cos AFAIK that's the one
>that the 50 uses.
And the specs for each drive shows this to be:
Hitachi DK23BA-20 20GB HDD:
Interface Transfer Rate Max. 16.6 MB/s (PIO Mode 4, DMA 2)
Toshiba MK6411MAT 6.4GB HDD
Buffer to Host 16.6MB/s (PIO Mode-4, DMA Mode-2)
>Of course, it shouldn't make any difference *how* fast the disk is provided
>it can take 10MB/minute or so ...
Do ya realy mean that "10MB/minute", or would you like one of these
Margaritas?
>which is well within any of these specs - if it's not ready when the
>program wants to write then the data should be buffered until such time as
>it is.<
>Normal (i.e. dos level) audio recording works like this: (please note I'm
>working from memory far too early in the morning :)<
>
>1) set up two buffers in sequential memory, big enough for a sensible
>amount of data, say a tenth to a quarter second. Maximum is 64kB cos that's
>all the DMA can handle. < ...
<snip>
>Any wonder it has glitches?
Phew! Quite a lesson. A couple more reads through, and maybe a bit more
will stick in what I laughingly refer to my "memory".
So I'm venturing a guess here that the reason I may be getting incrementally
better recording results on one HDD w/W98 vs another HDD w/W98, may be more
do to the way each W98 installation is working than it does with the HDDs...
and that both these HDDs should be able to be set up to recording properly.
And I'm getting the impression that I might want to try to track down some
DOS recording software and give this WavJammer a try on it.
Matt
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