Posted by Voinin on 05/21/06 05:54

Jeff wrote:
--
Space is big. You just won't believe how vastly, hugely, mind-
bogglingly big it is. I mean, you may think it's a long way down the
road to the chemist's, but that's just peanuts to space. - Douglas
Adams, The Hitchhiker's Guide to the Galaxy
> Voinin <vboing@boing.biz> wrote in news:126usca1t048m9c@corp.supernews.com:
>
>> When I record a DVD I turn verification on. (I got into the habit when
>> I used a tape backup drive back in the day.) When the disc is being
>> burned it starts out at 8x and finishes at 8x. So it seems that during
>> burning it's using CLV mode. However, when the verification process is
>> running the speed varies from slow to about 8x at the end. So it's
>> apparently using CAV mode. But when I rip a single-layer DVD the
>> download speed approaches 16x towards the end of the read. This
>> process, too, apparently uses CAV mode.
>>
>> My question: Why does the verification process take longer to read than
>> it does when burning or when ripping a DVD?
>>
>> FWIW I'm using Nero 7, but this phenomenon happens with other software I
>> have used to burn discs.
>>
>
> Because when you are verifying you are not just reading the DVD, you are
> also reading the same files from the hard drive and spending a bit of time
> comparing the two to see if they match. Your computer is apparently not
> fast enough to do this at the maximum DVD read speed.

Somehow I don't see this, especially since the DVD and the hard drive
are on different IDE busses. The system easily has the throughput to be
able to perform both operations at the same time. Consider also that
reads are much faster than writes and the verification process only
involves reads from both media.

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