Live streaming - requirements

[mariusblk]

Hello guys, new to this forum and 'industry' of live broadcasting. I have a couple of questions for the ones that experienced it before and know some more things.

I want to make a live broadcast using Windows Media Encoder for maybe 1000 viewers max and i was wondering the following:

1. What internet connection i should use ? Do you think that a 2 Mb/s connection with unlimited bandwidth would be enough ?
2. What video capture card should i use for a 720 kbs stream ?
3. Is there a special PC setup as i've seen that the use of the processor (T7200 from my laptop was showing some times 50% usage)
3. I also read that if you want to place the camcoder too far from the PC ~100 meters there could be a problem in loosing signal through wires is that true ? Should i use some amplifyer or isn't necessary ?

[JohnnyMalaria]

If you are planning to do this as a DIY project then you'll need a Windows Media server (WME only permits 10 connections). If I understand it correctly, you'll need Windows Media Services running on Windows Server. Rather pricey.

http://www.microsoft.com/windows/windowsmedia/forpros/serve/prodinfo2008.aspx

[creamyhorror]

1. What internet connection i should use ? Do you think that a 2 Mb/s connection with unlimited bandwidth would be enough ?

If each viewer takes 200kbps (already very very little), you'll only be able to sustain 10 viewers at most. Multi-streaming from a typical home connection just isn't practical afaik.

[Cornucopia]

That's why what Johnny Malaria said is true.

If you stream in a unicast flow paradigm, your bitrate needs are: Bitrate of media * # of users. That can add up REAL QUICK.
If you stream in a multicast flow paradigm, your bitrate needs are: Bitrate of media + ~5-10% overhead.
Multicast allows you to send the IP addresses of your audience/clients downstream to router nodes where the smart router will "clone" the signal and send it along to those clients that are downstream of it.

Of course, to do Multicast with WMV, I'm pretty sure you'll need Windows Media Server. And as has been said, that gets pricey.

If you don't want to do it yourself, and you can live with a "time delay" on your "live" material, you could set up a connection with a WM Server Online Service and upload it to them (they'll either have the bandwidth, or Multicast, or both).

Scott

[EddyH]

Now here's something I've been wondering about for a while ... shouldn't the point of a live stream be that you just send out singel packets but with multiple addresses, depending on how many people are connected? Sort of like how a regular IP broadcast works? Or does it simply "not work like that"?

When each packet is only ever going to be sent once and there's no saying how many people are going to be demanding it in real-time, it seems wierd to toss out hundreds of copies of exactly the same thing.

But in any case, I'd have horrors over using what sounds like a home-user class connection for any kind of web hosting above and beyond a personal resumé site, possibly with a few photos and small non-streaming videos on it. Uncapped or otherwise, the sheer amount of bandwidth - and fast latency - required makes it totally impractical. Plus even if you CAN broadcast out, each of the incoming connections will demand some kind of overhead, which will affect your outgoing bitrate.

2mbit/sec is barely enough to get good quality video coming in - and you rarely get the same upstream speed as down. Sending out even one copy will be borderline unless it's quite low quality. Worse if you have something like RealVideo surestream (multiple bitrate versions available depending on the viewer's own bandwidth). And if you're having to send out multiple copies on that line, well... do you remember watching Realplayer videos over a 56k modem? It'll be like that. Assuming you have no more than ~40 viewers, a full 2mbit upstream rate, and no extra overheads. There's a few internet radio stations out there being hosted off home connections, but there's probably a reason they run at around 24-48kbit/s...

A typical modern CPU should be perfectly capable of encoding a low-rez, low bitrate video such as that in realtime with space to spare. The main load on the system may come from having to make many duplicates of it, packetise them, send out to all your viewers and keep track of the whole affair. Network ops seem to put great strain on non-server systems for some reason. Possibly PCI(x) bus contention tying up comms for Capcard <> CPU <> RAM <> NIC or something.

EDIT: Just saw the multicast thing. Hmm. Interesting. So might have the bandwidth for it after all, then it just becomes a matter of keeping track of where you're sending it. If you can handle Bittorrent, then it should be possible.
New question: Can VLC support such things? Been thinking of using that as an alternative to the Microsoft version (which the guys here seem hot on for some reason, though it may well tie us to using *spit* WMV).

[mariusblk]

Thanks for the fast answers, and as i discussed with a friend you are right. There are too many steps and a hell of logistics, time spending and huge funds behind a Live Stream as i wanted to make so i guess this goes down first steps. Yet he told me about another sollution using Livestream as they have nice resources using the Premium plans.
And to tell you all about my project i can say that i want to use 4 camcoders linked to 4 PC's as i want 4 angles each of them in separate players. Now as far as i read on their specs this is possible through Network Plan as they provide 10 separate channels though i'll use just 4 of them.

Now the questions are:
1. At 720x576 will the quality of the stream be good enough or i need more - can u recommand me a camcoder and a video capture card for that ?
2. Now my internet connection with 2 Mb/s for each of the PC's will be enough to transmit the live event to their servers ?
3. Will those 1000 Gb of storage be enough for me to record 70 hours of stream ?
4. I heard that there is a maximum distance that u can place the camcoders from the PC's using RCA cables and another less shorter for firewire.

I would be more than excited if u could help me in this matters as i don't want to waste a lot of money for nothing. As i am new to this part of livestreaming is some kindda hard to find all the answers.

[Cornucopia]

Ok, now you're dreaming...

What you'd need would be (at minimum):

4 Pro DV cameras (Genlocked) with Firewire in to one MONSTER PC with multiple cards (DON'T use multiple ports on the same card!!).

Enosoft DV Processor (?) to handle multiple synchronized DV-ins on the same PC.

A Windows Media Streaming server of your own - JUST to be able to live encode multiple streams. Regular WME won't do more than 1 stream at a time.

Then you'll have to stream to an Online Service's "waystation", where they have the bandwidth and CPU capacity to handle requests from 1000s of users in Multicast form.

This all starts to not really be "LIVE" anymore either, with all the latency from the capping, processing/encoding, upload streaming, download streaming, etc.


You need to walk before you can run, as your grand idea would cost you $1000s.

Try using DV processor to create a "Quad-split" (picture in picture with each angle downsized to one the 4 corners). Then you can encode only 1 stream live, etc.


Oh, and re: Maximum Distance,
Yes there is for Firewire (around 15ft?), but you can get "repeater/extenders" for them as well (for $$$).

Might be better if you just used 4 webcams+4 computers (sitting right next to them), encoding live to 4 streams, with 4 network connections, and you create a webpage that allows you to choose 1 of the streams. They won't be synchronized anymore, but who are you trying to please?

Scott

[EddyH]

(removed by author)

[EddyH]

And to tell you all about my project i can say that i want to use 4 camcoders linked to 4 PC's as i want 4 angles each of them in separate players. Now as far as i read on their specs this is possible through Network Plan as they provide 10 separate channels though i'll use just 4 of them.

OK, to read between the lines on this, you're either doing some kind of strange concert or art installation broadcast, OR you're after a way of doing remote CCTV surveillance. In the latter instance, you really don't need such high quality. A lot of still in-place installations I've seen use a common idea of taking four input feeds, cramming them down to (say) 384x288 (basically chucking half of the PAL fields for simplistic deinterlacing, and preserving a moderate amount of horizontal rez - the NTSC equivalent would be 320x240), then arranging them in a 2x2 matrix on the ONE screen (or in the one video feed).

You can get simple 4-way composite video capture cards that will let one PC slurp in all these, and then either the built in software will handle it, or you can pipe it through (say...) Virtualdub and a simple Avisynth script (4x inputs, Reduceby2, stackhorizontal, stackvertical). Reduce the framerate by 3 or 4 times (8.3 / 6.3fps PAL, 10.0 / 7.5fps NTSC), bomp it into an encoder at about 500kbit/s (audio, 22khz mono, 32kbit) with the "quality" slider as high as the PC can manage, throw the result at the internet, and you're done. If you want to get higher quality e.g. for purposes of making out someone's face you can maybe arrange to blow up one of the camera feeds to full screen, full rez - or just put the cameras on PTZ mounts so you can get Perpy McPerperson's face to fill the screen... 320x240 is easily enough for a photofit.

If you ARE doing the arty concerty thing... you MIGHT be able to get away with one PC and a 2mbit link. MIGHT. After a bit of playing with the numbers, you want something like 512x288 for each one (16:9 widescreen, square pixels... if your camera offers 16:9 output), which will allow you to have "full" motion 25fps, similar field-discard deinterlacing, good horizontal rez, and not too much artefacting of the video or (stereo) audio at a combined bitrate of 400-and-some. (Say, 4x450kbit, equalling 1800kbit total... leaving some headroom for control messages, email and the like).

You'll need a pretty good PC (as you're encoding realtime at near-HD resolution, effectively - 1024x576 in total, with 4-8 audio channels), 4 stream support from whatever service you're using (OR: them allowing you to use a single 1024x576 one, which can then be trick-split back to 4 quarter views - again, if it's just on your own machine, AVIsynth can do that), and rock solid knowledge that you're getting 2mbit UPSTREAM and nothing is going to perturb that. Even if you fall back to 1.5mbit, you're ruined.

Now the questions are:
1. At 720x576 will the quality of the stream be good enough or i need more - can u recommand me a camcoder and a video capture card for that ?

Ruddy heck mate, what exactly are you doing, over the internet, that SD broadcast quality might not be good enough? Note that YOUTUBE only recently started offering higher quality than 480x360.... and on a personal note, I've done single-stream encodes (mixed down from a multicamera source) for use on my workplace's own internal media server and website at a YT-HQ-esque 640x360 (and initially an overall bitrate of 800kbit/s) - and effectively been told to "back the quality off already! we're not made of storage/bandwidth!". Note this is at a higher educational institute with multiple servers and at least 100mbit of connectivity in both directions...

Also in the PC realm, that image will be all bent out of shape, particularly if it's widescreen (and unless its surveillance, you probably want 16:9) - do be sure to resize it properly if that's what you get incoming.
Not to mention capture cards are quickly becoming yesterday's news, unless it's, say, HDMI. You can get cameras that connect over USB2 (or 3... or if you really have to, FW400/800) that give just as good a result if not better (because light MPG compression beats a cheap composite decoder hands down, and DV usually does).

If you really want to go HQ, there are plenty of 720p and 1080i hi-def cameras about (and a few 1080p ones - that by using MPG4 still don't take up more data bandwidth* than SD DV) that should be able to connect over USB for live capture. From which you can get a nice clean standard-def image for the time being, with PC-friendly progressive scan, then move up to actual hidef if you decide to stick with this game. Or if you don't, well, you can make some really awesome holiday videos.
(* by which I mean raw, unadulterated, 25 megabit, 12Gb-an-hour DV... the top whack HD encoding that i've seen is something around 21 to 24 megabit... so it'll happily trot down a USB2 cable with oodles of headroom)

((I'll admit, actually - I know of those cameras because I'm considering them for my own work. The sensors in actual 576i DV cams (technically SD-card cams), particularly the affordable ones, are somewhat borderline on resolution and light sensitivity even at 1:1. Try to digizoom on a slightly too-distance audience member in postproduction, like I did, and it looks awful, and at full rez (e.g. putting onto DVD) there's noticable noise, oversharpening and residual MPG encoding artefacts. Plus there's the goddamn interlacing, which means lowering the pixel rez for internet video doesn't bring as much "false" improvement as it should.
If I was to start off with even a 720p source (1080/50p for preference!), a number of these things could be improved; a nice, clean, sharp image at 1x zoom 576i (effectively "oversampling" by 2.2x... or 4.4 using trick interlacing methods) with reduced noise and barely detectable sharpening, with effects amplified in the online version (rather than LOSING rez from deinterlace), and the ability to zoom in by at least 2x before the DVD image approached even the level of the original camera.... and we can then go for proper HD service when the equipment and connectivity to deal with it is finally affordable. Mmmmm))

2. Now my internet connection with 2 Mb/s for each of the PC's will be enough to transmit the live event to their servers ?

Not for four streams with the kind of resolution you seem to be thinking of it won't. Back it off to more sensible, web-friendly settings and you might be OK. Do, do, DO bear in mind that unless you have double dog dribble checked with your ISP that it's a guaranteed 2mbit/s UPload, you will likely have FAR less - largely for this exact reason, to stop everyone and their dog starting their own public access TV station without paying extra for the privelege. My own "10mbit" connection (which is sometimes 8, sometimes 5 and sometimes 2.5mbit download) rarely gets more than about 512kbit upload; I think I once saw 768.... But yes. TWENTY times slower than the best download speed, and still FIVE slower than the worst. And I'm on a good provider. On a non-explicitly "2mbit" link (ie a consumer one with "up to 2mbit/s download") I'd expect to see something like 256-384kbit upload speeds (the higher the download speed, the worse the discrepancy; my original 512kbit line uploaded at 128).[/quote]

3. Will those 1000 Gb of storage be enough for me to record 70 hours of stream ?

Easily. Some rough maths:
2 mega-bit max send rate = 0.25 mega-bytes per second (divided by 8)
Or 15 megabytes / minute, 900 megabytes / hour, or roughly 0.9Gb.
70h x 0.9Gb/h = 63Gb. And you'll almost certainly be transmitting at a lower rate than that even if you do have a full 2mbit uplink, because you have to allow for overheads like control signalling, error correction, congestion etc.
In fact, 1000Gb / 70h = more than 14Gb/h, which would be enough to record "raw" DV (or the aforementioned full-HD) with room to spare.

4. I heard that there is a maximum distance that u can place the camcoders from the PC's using RCA cables and another less shorter for firewire.

Yep. I can't quote them off the top of my head, but Firewire, like USB and eSATA, is pretty short - something like 5 metres, which is NOT much even in a dead-straight line (it won't be). It's meant more as a one-time transfer link rather than for live work, though it can work that way.
Composite video can go for hundreds of metres if you have a good quality, impedence-balanced, oxygen-free, twin shielded cable, but you pay for that in scrappy quality (bad even at 1 metre unless you have pro grade kit, and gets worse with distance). Something like S-Video or analogue component might be a workable compromise (intermediate range and quality) if your kit supports it.
Or... IP cameras running over either UTP (100m max, 100-1000mbit possible, allows Power Over Ethernet), Coaxial (185m, but only 10mbit, unreliable and no power) or Wireless (variable, usually <50m, usually supporting at least 10mbit but prone to speed-eating interference - however, it has the advantage if running cable is difficult but powering them isn't). This could be achieved with "dumb" cameras by having a small, low end computer (say a netbook with a USB capture dongle) local to the camera, connected by ethernet to the one acting as your main local server.

I would be more than excited if u could help me in this matters as i don't want to waste a lot of money for nothing. As i am new to this part of livestreaming is some kindda hard to find all the answers.

Hopefully we've saved you from that, then, unless I'm just being paranoid!
Good luck with it though - I wouldn't wish to crush your spirit of adventure. Just wanna make sure you're heading up Everest with something more than a pair of trainers, summer hat and lunchbox...