Video Streaming - Where's my bottleneck?

[Mr. Tinker]

I've been put in charge of creating/managing a TV station for the school district that I work for. I want to have the ability for live broadcast of games held in the gymnasium (basketball, volleyball).

The problem I face is that the gym is pretty far from where we will be broadcasting, so I need a way to transmit the video signal in near real-time. In other words, I need a way to transmit an analogue video signal across a distance of a few hundred feet.

My tentative solution is this: set up a "mini-studio" in the gym, send the analogue video feed to a canopus ADVC110 firewire device (basically a firewire video signal) and to a computer via firewire, encode with Windows Media Encoder for live broadcast, signal goes across the LAN (could be dedicated) to a computer for decoding and the video-out signal goes to the station modulator for broadcast.

In tests that I've run recently, The encoded image was noticeably lossy but did not suffer from dropped frames. Even using "DVD quality" pre-sets on WME, and even when I bumped the signal up from 2Mbps to 7Mbps the image was still so-so with motion in the frame. So I tried sending the signal full frame, uncompressed along with uncompressed PCM audio.

The bandwidth for this is 110Mbps.

I set up two computers with Gigabyte ethernet controllers (not on CSA) for my test directly linked to each other (computer--ethernet cable--computer). Both computers are as follows: 3.4P4 prescott on an Epox 5epa+ mb(915p chipset), 1gb DDR ram, Marvell Gigabyte ethernet controller. Everybody has the latest drivers and everything.

The uncompressed video stream on the receiving/decoding computer is very choppy, maybe 1 frame a minute, when it actually works. I can't figure out what is causing this. The encoding machine shows a ~75% CPU load with no frames dropped. The dedicated gigabyte ethernet should be able to handle 110Mbps, and the decoding machine hangs at around ~15% CPU load, so WHERE'S THE BOTTLENECK? Why is the video incredibly choppy if no component seems to be at 100% capacity? Maybe I don't have enough ram for the buffer?

Any suggestions are greatly appreciated. I wanted to post this question to the aces of computing bandwidth.

Or, maybe someone knows a better way to send an analogue video signal across a few hundred feet.

Thanks,
Tink.

[Ugly n Grey]

Add a simple booster to the first ten feet of the loop from your camera even a cheap 10dba booster will do it. You should have a lot better reception within 300 feet. It's easier to transmit analog video than just about anything else....

[Mr. Tinker]

The signal will be coming s-video and audio RCA L/R from a Video Mixer. It would be very hard/impossibe/no one would be willing to run new cables through the building.

What kind of cable are you referring to? RJ11?

[Ugly n Grey]

I thought you were running standard coax... low budget, low transmission needs expecially if you sending out over the net, but never mind, I assumed and made an ass of myself .

In any case, Black Box in Canada is where I usually shop for wireless transmission items for video/audio, but I have no idea what your budget is so I'm not even going to start on that.

In terms of your test setup, I would suspect your network first, have you tested the throughtput across the LAN (two cards makes a LAN I suppose :D) thoroughly? Checked it for collisions and noise? Run a sniffer program and see how many packets are being dropped etc...

In theory your setup should work....

[Mr. Tinker]

First of all, I forgot to say thanks last time. Thanks.

$12-15K USD for all equipment this year (includes a lot of other stuff).

I ran a direct link between the two computers. The actual setup would use low cost dedicated gigabyte router(s) or switch(es) with no other computers on it at all because our existing infrastructure is 10/100 as you'd expect.

What kind of programs can I use to run the tests you suggest?

[Mr. Tinker]

P.S. UnG, could you send the link and suggestions for wireless transmission of A/V. I need to find a way to send the signal from the cameras on the floor up to the mini-studio.

[Ugly n Grey]

You are most welcome to whatever little direction I can give.

Well first things first, On the network card side for both units, turn off autonegotiate and set the link speeds manually to the highest available full duplex (also try half duplex). Make sure your crossover cable is rated for the gigabit ethernet. For the sake of argument, disable all protocols other than IP and uninstall QOS if installed. Set all IP variables manually using an assigned address. Test a basic ping and file transfer to from each computer.

When everything is working, install something like Securepoint Network Test Tool 1.5 (or another freeware analyzer) and set it to log and monitor traffic on your network. Start bombarding the network with file transfers, keeping in mind an average ATA hard disk can only read sustained data on an SATA I interface at around 65MB/s (more for better drives). When you are satisfied that the network is OK, try your test again and we'll see what needs to be fixed.

In terms of what wireless devices to use, I am not up to date any more. The last one I hooked up was a line of sight device used for RG-59 coax, but if you call sales at Blackbox.com they probably have a device that can help (they are in PA but are a catalogue outfit).

On other notes, on the fly encoding works better with dedicated encoding cards in my opinion such as those found in HTPC's. There are whole foums dedicated to this such as htpcnews.com, www.htpcforums.com etc....

Again, I think your idea is perfectly reasonable and the tools to support you are already out there. If I can be of help feel free to ask.

Ugly

[Mr. Tinker]

As a follow up, today I found this wonderful freeware program: DVTS (http://www.sfc.wide.ad.jp/DVTS/)

Very easy to use. It sends a digital video signal (firewire IEEE1394) over IP, uses 30mb/s of network bandwidth, runs on many OS's, and video and audio look completely lossless. The "serving" machine uses almost NO cpu, and the client uses less than 20% cpu on a 3.4Ghz P4. Perfect.

[Ugly n Grey]

Is it up and running and working well? Wow, it's been so long I forgot I even subscribed to this thread :)

[Mr. Tinker]

Got it working on our school network in just a couple minutes. Standard def video stream with stereo audio, perfect video quality. I could also use the stream to do captures in AVID as if it's a normal local firewire input. Pretty cool huh?

[Ugly n Grey]

very cool, congratulations :)

[Mr. Tinker]

This little free program saved me a couple thousand in hardware, not to mention cost/time/red tape to run fiber a couple hundred meters.

UnG, could you suggest a good, solid, dependable "I go through concrete walls like tissue paper" wireless AP and NIC that can filter by mac address and sustain at least 30mb/s thoroughtput? You seem to know a lot about networking. Or point me in the right direction.

[Ugly n Grey]

Unfortunately 2.4GHz doesn's pass through walls worth a crap without some kind of signal degradation. My solution in factory settings where there are lots of block walls internally is always the same, whack a cable through the wall and put a repeater on the other side. While signals DO go through walls, there is nothing that doesn't experience ups and downs (spikes) in performance. I've tried every one Cisco and Nortel has been able to dream up for commercial use, so price was no object. It's not that they didn't work, it's just that throughput was so up and down it drove me nuts...wish I had better suggestions