Re: [Frameworks] The Digital Video Exhibition Problem: And An Offer To Address It

From: Aaron F. Ross (email suppressed)
Date: Sun Dec 05 2010 - 15:09:46 PST

Brook Hinton <email suppressed> wrote:
>David - that does indeed work, assuming a dead-compatible player.
>Before folks get too over the moon though, it's NOT blu-ray quality,
>though it is a BD spec. I can't remember the bandwidth limitation,
>but I think significantly below the max for Blu-Ray

I looked this up, and the nominal AVCHD-on-DVD bandwidth limit is 18
megabits/sec. The bandwidth limit for the AVCHD format proper is 24
megabits/sec. I've had success burning a 24mb/s file onto DVD media,
and it played fine on my Blu-ray player, but of course your mileage may vary.

Anyway, either 18mb/s or 24mb/s should be enough for most 1080p
footage. It's true that commercial Blu-ray discs can be authored at
up to 72 mb/s, but most of the ones I've seen average about 24 mb/s.
Experimental work with a lot of motion/detail may need a higher
bitrate than 18 or 24, so if that's the case, just encode at a higher
rate and burn onto Blu-ray media.

In any event, encoding issues still exist in the multimedia file
domain. If you want your work to look good, you still have to know
about this stuff and encode your work appropriately.

>I'll end my anti-round-disc diatribe with this and then fall silent:
>in multi-maker exhibition situations i've found DVDs (and by
>extension Blu-Ray) incredibly awkward on a physical level (cueing,
>loading, unloading, etc.)

Well, that does mean the projectionist needs to do changeovers like
in the old days... look at it as job security for projectionists.
:) And of course you need a switcher or two projectors as well, so
it does get expensive for DIY operations. But established
institutions can certainly afford it.

I'm just really down on the whole "dump the files in a playlist and
let it roll" method of exhibition. My main objection is that, even
today, computers don't have much elegance in the way they handle a
discrepancy between source frame rate and display scan rate. In other
words, if the media is encoded at 23.976 fps, and the desktop is
displaying frames at 60 Hz, you're likely to see horrible horizontal
tearing in the middle of the frame, or blurry frame blending. Pick
your poison. With dedicated hardware such as a Blu-ray player, this
is not an issue.


Aaron F. Ross
Digital Arts Guild

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