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Date:      Fri, 31 Aug 2001 14:29:48 -0600
From:      "Kenneth D. Merry" <ken@kdm.org>
To:        Nick Sayer <nsayer@FreeBSD.ORG>
Cc:        freebsd-multimedia@FreeBSD.ORG
Subject:   Re: Slow DVD?
Message-ID:  <20010831142948.A57711@panzer.kdm.org>
In-Reply-To: <200108312000.f7VK06d00646@morpheus.kfu.com>; from nsayer@FreeBSD.ORG on Fri, Aug 31, 2001 at 01:00:04PM -0700
References:  <200108312000.f7VK06d00646@morpheus.kfu.com>

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On Fri, Aug 31, 2001 at 13:00:04 -0700, Nick Sayer wrote:
> I have been disappointed so far with just about all the DVD playback options 
> available, but I believe I have an explanation now.
> 
> I have a relatively old DVDROM drive. The virtue of it is that it's 
> regionless. Here's what the kernel has to say:
> 
> cd1 at ahc0 bus 0 target 5 lun 0
> cd1: <PIONEER DVD-ROM DVD-303 1.09> Removable CD-ROM SCSI-2 device 
> cd1: 20.000MB/s transfers (20.000MHz, offset 8)
> 
> If someone were to "rip" a movie using a particularly naughty piece of 
> software, it turns out that xine and vlc can both play the resulting mpg file 
> perfectly.
> 
> If someone were to use naughty versions of xine or vlc, one would find that 
> the playback skipped a lot of frames and looked basically crappy, but the CPU 
> is 60% idle.
> 
> These two circumstances tell me that perhaps the drive itself is the 
> bottleneck. Does anyone know of any magic sysctls I might try on cam to speed 
> things up?

I don't think there's really anything you can do from that angle.  The
drive will likely just go as fast as it can.

The drive specs say that it can do from 2.5-6.0X for DVD-ROM, so that
should be enough.  I would look for some other software issue, perhaps the
amount of buffer the programs keep around.

If you want to see what it thinks is its minimum/maximum read speed, use
cdrecord's '-prcap' option.

If the current read speed isn't the maximum, there may be a way to tweak it
to go faster with the right mode page.

Ken
-- 
Kenneth Merry
ken@kdm.org

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