Re: [linux-audio-dev] design question for HDR

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Subject: Re: [linux-audio-dev] design question for HDR
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Mon Apr 03 2000 - 14:58:31 EEST


>I successfully recorded 12 tracks simultaneously with VST & MacOS on
>604e/233 + SCSI-1 (i.e. nothing very spectacular by current standards) both
>to internal IBM scsi disk & external (JAZ) cartridge . No interleaving of
>files - however, there's no VM involved. This is the most I can do with my
>12/12 I/O card - but there did seem to be at least a little steam left.

Recording is not a problem, and never has been. Playback is the
problem. Recording is easy - you just use enough memory to hide the
fact that the disk+controller+buffer-cache can't keep up in the
short term. But playback is different - if you don't have the data
when you need it, you don't have it ...

>I guess that, effectively, the OS, application etc. is on a separate
>physical controller from the audio data - maybe that will help.

Yes, thats a possibility. Right now, they are different disks, but the
same controller.

>Not very helpful maybe - apart from an 'existence theorem' - although
>Steinberg did make a fairly big deal about selecting disks with <12ms seek
>times.

Mine have 4.5ms and 5.7ms seek times, so this is not the problem.

>(using much less powerful processors - 25Mhz 68020) I've used pre-allocation
>of disk space to avoid some of this.

My files are all preallocated. You will never be able to keep up with
more than about 4/5 tracks if you allocate the files as you go.

>>Therefore, I feel that this (interleaving) is a crazy design for an
>> HDR system,
>
>100% behind avoiding this - it would be a nightmare for some of the apps I
>have in mind.

Glad to hear someone else agrees with me on this.

--p


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