Transcoding / Streaming HDTV?

[scgroup]

I am seeking some advice about HDTV from the encoding and streaming
experts on this forum.

I live in a rural area near Reno, Nevada, USA, have a small apartment
in Paris, and enjoy watching American satellite TV while in Paris. My
present system provides decent quality from NTSC sources, streaming
WMV9-encoded video at about 2.6 Mbps. I'd like to upgrade to HDTV,
mostly for sporting events broadcast in 720p (~18 Mbps MPEG-2 stream),
though the system would ideally also be 1080i capable.

The present Internet connection in Reno is a 5.8 GHz wireless link to
a small ISP that primarily serves business customers. Outside of
business hours, I can upload at ~5 Mbps, with the possibility of speed
upgrades. In Paris, there is ADSL from Free Telecom.

In attempting to design the new system, I'm facing serious challenges
concerning transcoding performance and Internet bandwidth. Under
consideration are 5-, 10-, and 20-Mbps systems.

5 Mbps:

I transcoded some HD test clips to H.264 (also VC-1/WMV9 and RV10) at
5 Mbps, and the quality is impressive. This would be a good solution,
if it could somehow work in real time. It's compatible with my
current Internet connections and doesn't frivolously waste lots of
bandwidth across the Atlantic. Trouble is, on my present PC here
(Athlon 2200+), VLC takes ~10 seconds for each second of video. I
suppose that a recent processor would run 2 to 2.5 times faster, and
another factor of almost two could be gained from a dual-core CPU.
But that still leaves me with less than half the needed horsepower.
Does VLC (or some other transcoder) support multiprocessor systems, or
have a way to distribute the transcoding load among several networked
servers? If so, how much "iron" is needed to reliably transcode HDTV
in real time?

10 Mbps:

IMO, one needs 8-10 Mbps to get equivalent quality in MPEG-4. On my
test machine, transcoding takes VLC ~2 seconds for each second of
video. So, I assume that a fast dual-core or hyperthreading CPU could
keep up with no trouble. Can someone please confirm that? With this
approach, I'd need some Internet upgrades. The Reno side is no
problem, because the ISP is getting a faster pipe from their upstream
carrier. In Paris, replacing my ancient modem/router with an ADSL2+
unit should give ~12 Mbps useful download speed (1619 meter loop).
Have any of you streamed HD over ADSL2+?

20 Mbps:

This is the ugly solution: no transcoding, just beef up the Internet
service to support the raw MPEG-2 stream from the satellite.
Obviously, that would give the best quality, but it seems a shame to
push 18 Mbps across the pond just to watch TV. Also, it's expensive.
In Reno, not only would the radio link need to be upgraded, but I'd
have to do some marketing for the ISP, so they'd have enough business
to justify a fatter pipe! In Paris, I'd have to get a second account
from Free. How would I combine the two links? Is there a software
solution (with sufficient performance) where the VLC player could have
two NICs, or two IP addresses on one NIC? Or, would I need to buy a
router that can do multilink VPN?

Which, if any, of the above scenarios make sense? Any suggestions
will be greatly appreciated.

Thanks,

Stewart

[cygwin98]

If you have a dual-core Pentium D 3.0Ghz+ or Pentium 4 3.6Ghz+, I am
pretty sure that you can achieve real-time encoding into mpeg4 at 8Mbps.
Make sure that you enable multithreading support in VLC though.

[The DJ]

Ehm. you should try that first. i have no idea about the reliability of a 10Mbs stream over wireless links and what not. But i wouldn't put my money into it just yet.

[scgroup]

Many thanks for the replies. I am happy to hear that the transcoder can
use multiple threads. (The documentation only speaks about separate
threads for different tasks, e.g. one for decoding and another for video
output.) Since I'll be assembling a new system for this task, I'm curious
what OS you recommend.

The network side is not a problem for me. I don't stream in the usual
sense; the server transcodes to a file. There is a home grown UDP-based
FTP program that follows the growing file and moves it over the link,
using a large window and selective retransmission. At the receiving end,
I wait about 10 minutes before starting the player. This allows for normal
bouts of network congestion. On very rare occasions, the player reaches
the end of the growing file and stops. No big deal, I wait a few minutes,
start it up again, seek to the right place, and continue watching.

I have been watching the SD content on my PC monitor, but would like to
get a big LCD panel for HD. What display cards with DVI or HDMI output
do you recommend for HD playback? (The PC is already set up dual boot
Windows XP / Fedora Core 3.)