[streaming] Re: need to set up a US digital TV demo

[Tristan Leteurtre]

On Fri, Aug 08, 2003, Jerry Scharf wrote:
> I am new to the list and did not find any information in the archives. I am 
> trying to create a US terrestrial broadcast comparison and was hoping your 
> software could do this. I have someone who is completely convinced that 
> when you put video on top of IP, it will always look bad. So I want to set 
> up a demo that can show him as close as I can to a identical setup demo.

Indeed ! We can stream DVD-quality videos  over high bandwidth networks
(LAN), and the video plays very smoothly. The bottleneck is not the
technology or the software (videolan does it well !), it is the network.

> What I an thinking of doing is the following (I live near San
> Francisco): Set up an antenna pointing at the local broadcast tower.
> Start with a standard 4:3 aspect ratio NTSC television. Put a splitter
> on the antenna and run one side to the antenna input of the TV. Route
> the other side into a PC based tuner that will extract the transport
> stream of the same station, then put it on the wire as a UDP packet
> stream (about 4Mbps for US terrestrial.) Then have another PC catch
> the UDP stream, decode it and send out a s-video port and back to the
> TV. So you can look at the same broadcast at the same time by flipping
> the TV between the antenna and s-video ports. I want to avoid all
> transcoding so the signal quality will be as good as possible on the
> reconstructed image.

This looks like a very good scheme, and I am sure the demo will prove
the expected results. Nevertheless, speaking of video quality, notice
that the s-video TV output of mass market graphic boards is usually of
bad quality. So you may have a worser image quality (tiny flickers,
jitters) compared to a computer screen.

So to get rid of this problem, you may either use a VGA computer screen
to display the video or use dedicated set-top boxes : some of them have
special video chips to render a good composite TV-output signal.

> I have seen four or five PCI cards that will receive US terrestrial
> digital tv, but nothing that can hook them up to IP streaming software
> or turn it back to video on the other end.

I have personally done this kind of demo using the Hauppauge Nova-T PCI
board, which is supported under Linux with the linuxtv.org drivers, and
using the VideoLAN server vls as a streamer. The digital TV channel were
received from the antenna and live streamed in multicast through a 100
Mbits network. Some computers and set top boxes could play the video
very smoothly in high quality.

> What is at stake here is whether a proposed local fiber plant in Palo
> Alto will use a separate analog video delivery system or use IP. Until
> we can demonstrate that that a digital system looks as good or better,
> we will get an analog system that will soon be obsolete.

So I hope you will be able to set up your demo ! I am quite confident.

Regards,

-- 
Tristan Leteutre
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