I'll have to play with that -- I've got a capture card I wouldn't mind
dropping in my server box, which is too slow to compress anything real-time,
but it'd be really convenient since the cable modem's in with the server
already, so all I'd have to do is drop a splitter in the closet with them to
get cable inputting to the TV card.

----- Original Message -----
From: "Jason Pepas" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; "David Geoffrion" <[EMAIL PROTECTED]>
Sent: Monday, November 25, 2002 12:37 PM
Subject: Re: [Siglinux] capture tv on one machine, compress on another


On Monday 25 November 2002 04:38 am, David Geoffrion wrote:
> That's really cool.  You don't have any bandwidth issues sending
> uncompressed streams over ethernet?  I'm not sure what the bandwidth
> requirements are for an uncompressed A/V stream, have you tested that over
> wireless?

hmm, well I thought the dumpstream was uncompressed, but it looks like I was
wrong.  I tried using dumpstream and socat to play a video over the network,
and then tried ssh -X.  The dumpstream method used about 50KB/s, and the ssh
-X method used about 1.7MB/s (this was a small resolution asf which was
really compressed).

Of course that's just for video playback of an already compressed stream.
For
video capture, the stream would still be uncompressed.  For 352x240, i think
its about 6MB/s.  I tried an SVCD once (480x480) and that was already
saturating a 100Mbit pipe.  However, ethernet channel bonding is cheap
nowadays, and using three NICs people have achieved sustained bandwidth of
~260Mbit/s, which should be just barely enough to throw an uncompressed
720x480 (DVD resolution) stream over (that's probably the upper limit of
what
you can usefully capture off tv or cable).

for wireless (~11Mbit/s, 1.375MB/s), the best you can hope for uncompressed
would be about 160x120@24fps (~1.3MB/s).  However, you could just dumpstream
the audio, and have that compressed by a sepparate machine over wireless.


But if you are just looking to be able to play a compressed video over
wireless, NFS would use the same bandwidth as the dumpstream & socat method,
and would be a lot easier.

by the way, I have some other notes on neat things you can do with socat:
http://jason.pepas.com/linux/notes/socat.txt

-jason pepas


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