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WebStreaming - and live video production

"I can help to guide you along the learning curve"  - writes Martin Kay
 

Working out what you need in order to set up for live video production can be quite a daunting task, not to mention the operational techniques that will be required to use it. What I mean by "live video production" is any sort of live transmission (typically over the internet these days), or video recording, that comprises more than a single source. In other words, anything that goes beyond recording direct onto a camera, or transmitting the direct output of a single camera. The "live" element is the switching and combining of multiple feeds, either from cameras, pre-recorded video playback, text-based captions, graphics & computer output and other remote feeds. At one time this would have required a fully-manned purpose-built TV studio or Outside Broadcast unit, but these days the entry-level hardware requirements are far more modest, and a surprising amount can be achieved by a single operator.

Live video streaming and vision switching on a PC using VidBlaster

Finding the balance between hardware and software

Blackmagic Decklink Mini Recorder HDMI SDI capture cardHardware will usually only do what it does when you buy it, so the argument goes, but software is far more more versatile and can be continually updated to provide improved features. Computers have changed the face of broadcasting in so many ways, and the benefits have certainly filtered down to all levels of video production, giving lower-budget users functionality that was once the exclusive domain of the TV networks. But it would be a mistake to think that computers are the answer to everything production-related, and that it's just a matter of finding the right app. Handling multiple streams of video in real-time, particularly at HD resolutions and frame rates, is not something you should expect to do on every laptop (yet), for example, and is one reason why there is still a place for some dedicated hardware. Off-loading the tasks which require the most "brute-force" to external hardware will leave the computer with more resources to do the things it's good at, one of which is providing a highly customisable work surface from which to control everything. But that in itself is another reason why there's still a place for hardware. There's only so much that can be done with one pair of hands using a keyboard and a mouse, or even a touch-screen. And not every task lends itself to these sorts of controls.

Audio mixer slider fadersLive audio mixing is a prime example of something for which hardware still offers a very effective solution. A row of sliding faders offers a tactile multi-finger user interface which is hard to beat at a practical level. Also, audio equipment generally is now at a fairly mature stage in it's development, with the possible exception of radio transceiver units, and any investment in things like good quality microphones, headphones and mixers is unlikely result in the same sort of rapid obsolescence as experienced with other electronic items like computers, phones, TVs and cameras. As such, buying used equipment is a perfectly viable option, and most of my personal professional audio kit was either bought new 20+ years ago, or has been bought as used items (mainly from ebay) more recently.

VidBlaster software vision switcher in action for sports broadcasting

VidBlaster and vMix - a video production control room in software

Two of the software solutions I've used are VidBlaster and vMix, both of which are innovative vision control systems for Windows PCs that emulate many of the functions found in a TV studio or OB production control room video mixer. You can read a more general overview of vMix on the vMix page.

So how do you get the best out of something like vMix? The first thing to realise is that the processing power required is directly proportional to the product of the frame size, frame rate and number of source modules in use. So broadly speaking, if you want to have quite a few HD video sources, You'll need at least a quad-core i7, perhaps even a hex-core i7 or an i9 with up upwards of 10 cores. More RAM, or fast disks (eg SSDs) won't help with the basic video throughput either if your CPU isn't powerful enough, although you will benefit a bit from having faster RAM, and SSDs will be make a difference if you're doing video replays or making multi-channel ISO recordings. However, the one other component which will make a significant difference to performance in vMix is the graphics card, and something from the Nvidia GTX range, with 3GB or more RAM, from the GTX 1066 up to the GTX3080, will give hardware acceleration to both image processing and video encoding.   VS 626 HDMI Scaler & Frame-rate Converter

Another way of optimising performance is to try to ensure that all your video sources are actually delivering video to the computer at the same resolution and frame rate as you set for the profile. Any mis-matching video sources can be scaled in software, but if you feed in full HD video at 1920x1080 when you only need 1280x720, then you're giving the computer more work to do, if it's possible to set the source to 1280x720. This is where off-loading such tasks to hardware can bring benefits, with HDMI Scalers like the TV One VS-626 (aka Atlona HD-560) providing both up/down re-sizing and frame rate conversion when needed.

Of course the different ways of getting video into the PC will also have an influence on the end result, and not just in terms of video quality. Different devices can introduce differing amounts of video delay which will cause problems with audio lip-sync. Startech PEXHDCAP HDMI & DVI/VGA/analogue PCIe capture cardDigital video processing inevitably causes some delay between input and output, but as long as it's constant for all sources then usually it can be dealt with by the addition of a single audio delay line. What is not so easy to deal with is having multiple camera coverage where each camera feed has been given a different delay by the particular input method or device used. In this respect, it's best for all devices to be connected through the same type of interface, either by using multiple capture cards of the same type, or cards which can handle multiple simultaneous channels. As a rule, internal cards which connect to the PCI or PCIe bus usually introduce the lowest delay, along with USB3 which is a very fast external serial bus. Other USB devices (of the EzCap type, which has SD composite and S-Video inputs), use the slower USB2 interface and introduce a little more delay. Firewire/1394 also inherently introduces an even longer delay when used for video transfer, and IP cameras are likely to be even further behind due to the buffering that's often required.
(to be continued, maybe) 

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What we're about . . .      ZEN is not a traditional Audio-Visual dealer who started selling computers, nor is it a computer shop that also sells video products. You won't get any salesmen giving you the "hard-sell" when you call, just straightforward advice and information - which for some callers is the knowledge that they don't need to buy whatever it is they thought they needed! Above all you'll be dealing with someone with a wide range of experience and knowledge of both PCs and video production. We're not the biggest, nor necessarily the cheapest, but we are one of the longest established computer/video specialists in the UK.

Company history . . .      ZEN was started in the 1980s by Martin Kay, then working for ITV at Granada's Manchester studios, who built his first 6502-based computer in 1979 from an Ohio Scientific kit, bought in the USA whilst working as a Sound Recordist on a film shoot for World In Action. With the advent of the Amiga, which could be gen-locked to a video source, Martin started writing a variety of video-related software. This included subtitling & tele-prompting, ident clocks, scoring software for sports & gameshows, and specialist software to mimic other computer displays for use in TV film dramas like Cracker, Prime Suspect and A Touch of Frost. Martin left Granada in 1993 to concentrate on his computer-video activities with ZEN, following a natural path into non-linear editing systems, for many years the main business activity, although he still maintains an active interest in video production.

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Revised: 20 July, 2022