[K12OSN] RE: K12OSN Digest, Vol 16, Issue 15

[Rob Owens]

If this is meant to play on regular tv sets, then DVD
quality is probably not necessary.  A regular
(non-high-definition) has the same resolution as VHS
(approximately).  DVD's look better than VHS on a
regular TV because it is a better medium (less noise,
better color representation, etc), but not necessarily
because of its higher resolution.

Off the top of my head (might not be exact, but pretty
close):

VHS / standard TV  --  352x240
DVD                --  720x480

A DVD resolution file has double the pixels in both
directions, so it ends up being 4 times the size of a
VHS resolution file.  There's also bitrate and frames
per second to consider, both of which contribute to
file size.  In general, I think it's safe to reduce
the bitrate from the dvd standard, which is something
like 7000 kbps.  For web video, folks often consider
it acceptable to cut the framerate in half.  This
results is slightly jumpy video, which might not be
acceptable in a school setting.

-Rob

--- Sean Harbour <SHarbour at nwresd.k12.or.us> wrote:
> 
> I tried it out on my home network this weekend. A
> DVD quality file will not stream smoothly over a
> 10Mb hd link. Almost, but not quite. 100 Mb hd works
> fine. I would expect 1 or 2, possibly 3 clients on
> 802.11g would work also at DVD quality. It really is
> pretty slick, the quality is excellent. Plus,
> multicasting is out, the students need to be able to
> rewind and replay individually on demand. I've
> almost got it working on a PowerPC client also, it
> looks promising. Hopefully this week.
> 
> Sean Harbour
>   sharbour at nwresd.k12.or.us
> 
> > _______________________________________________
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> K12OSN at redhat.com
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