How do Live Switchers Work?
 

I am looking to use a live switcher for a shoot with 2 cameras and one computer monitor that will be outputting video footage (with audio) throughout the shoot.

I do not know quite how switchers work. Is it possible to output three sources (computer, and two hdv cameras) to a switcher and record onto one of the three sources, or is a separate recorder necessary? How can I maintain video and audio sync? Which cables and connectors do I need?

Would a datavideo se-500 or an edirol v-4 work or do I need something more powerful/expensive?

Any information would be appreciated.

A live switcher will take a VIDEO feed from your cameras and allow you to output a VIDEO feed to an external recording device and/or video monitor. In order to use computer video, you will need to get VIDEO, not an RGB signal, out of either the computer video card OR go through a Scan Converter to lower XVGA or whatever resolution to video (640x480). This will potentially wreak havoc on fine line detail and/or text.

Some switchers allow audio to be fed through them and switched ("audio follows video" switching). Or take your audio sources, run them through an audio mixer and loop them into your recorder and/or display/PA.

To avoid down rezing your computer video, getting a more expensive switcher than can accept computer signals in and upres video is possible. Analog Way is one of the leading switcher manufacturers in this application, which then requires you to find a way to record the end product.

when i need the quick&dirty mix, i use a videonics MX1 and a VGAtovideo converter.
All cabling is simple coax. This case is when the video is the main feed and computer is just used for few titles or logos.
If the PC is feeding the main signal (lengthy powerpoint presentation or excel spreadsheet) and video is just for few sequence, i do the reverse.
I use a vga switch allowing to switch between the PC and the output of the videonics table.
you can find for very cheap, converter that convert the video to VGA signal.
it works very well and the nice thing is most vonverter are usually very cheap

Shaun, thanks for the info.

So, generally, a component or s-video (or composite video, I suppose) cable goes from each camera into the switcher, and then is output to the recorder? Can the video output on the switcher go to a computer and record directly into an editing application? (I assume I would need a something-to-firewire cable for that...

Regarding audio, if I run the audio from a mixing board to the same recorder I use to record the output from the switcher, I shouldn't have any sync issues, correct?


Which switchers allow you to use and output hdv sources, such as the Sony HDR-FX1?

I missed this part during my initial response: if you are looking to live switch in HD, not SD, you'll be spending A LOT on a switcher (ie. $10k +) and a lot of the switchers in that price range want HD-SDI video, not analog component.

Input to a computer for recording could certainly be via capture card.

Sync issues should be non-existent or minimal if you keep the paths clean. The more devices either the audio or the video goes through before hitting the recorder, the greater the chance of sync issues. I do conventions in SD routinely and get a FOH (front of house) audio feed from the venue sound reinforcement system and pass it through my audio mixer before hitting the recorder, which is fed the analog output of my video switcher and I've never had sync issues. Of course, your mileage may vary... but if you're recording to NLE, slipping audio relative to video should be very simple IF you run into sync issues.

To the best of my knowledge, there still isn't a SUPER CHEAP video switcher on the market that can handle HD video. Everything I've researched starts around $10k and goes up quickly from there.

This seems to be a common situation..wanting to switch between a couple video feeds and a computer. I recommend as Shaun did to uprez your camera's composite/s-video to that of the computer. Even tho your cameras are HD, you may not be able to afford a hi-res video switcher.

FSR makes a thes combo units that are both a switcher and a scaler (uprez) in one unit that will take various video feeds and let you hard cut between them and VGA from your computer all in a 1U rack unit. If you want to use hi-res video then you need a bigger budget. Eagle and Ross are two I've used with SDI.

This is great info, but I still don't quite understand this concept of scaling ("uprezing"). Does this refer to the fact of matching the resolution of the computer source video to the other two cameras through the switcher?


Could you provide an example of a (sd) mixer that would provide scaling? I looked up FSR switchers and they were in the 20-30K range, a little high for my purposes.

For DV camcorders (or HDV in DV mode) and a Windows system, I have developed a *software* switcher that keeps everything in the DV format. At the moment, it is free (it has a clunky interface at the moment but works). It fully syncs the inputs so that there aren't any glitches when switching.

http://www.enosoft.net/dl.php?filena...erFilter32.msi

Only potential issue right now is taking the audio from the mixing board. However, if you feed it into your computer's line input, you can set things up to replace the audio of the switched video with your desired one.

(The plan is to add many more features and a versatile/easy interface).

First problem with this statement is that you are creating another down-the-line issue for yourself, namely how do you record this signal if you are going to start dealing with greater than SD resolutions (ie. UXGA etc.)?

There aren't any recording solutions that come to mind that will accept RGB signal and if you are getting into switching HD, the price goes up AND the availability of capable record decks goes down (you won't be able to find a switcher that has an HDV out on Firewire - at best, you'd get HD-SDI. Now what deck/format do you record to?)

Shaun,

I think that this is the second problem with my statement, while my first is that I don't understand exactly what scaling is: I assumed it referred to matching the computer's resolution to the other video sources in the switcher, not making it greater-than-sd. Please explain this, as I'm highly confused.

I don't yet have a deck that I record to, I use a Sony HDR-FX1. I'm in the pre-planning stage of shooting a radio show from a studio, and I am looking to understand exactly how switchers work and which products I should be looking at. Given that everything indicates that HD switching will be way too expensive, I'm looking for a switcher that will take at least 2 video sources and 1 computer, and output it to a recorder (I could get a 250GB hard disk recorder for that).

Scaling is changing the resolution. SD in NTSC-land is 640x480 or 720x480. Computers have many resolutions but are mostly (these days) 1024x768 and up.

Uprezing Video is changing it to a higher resolution. If you are switching in Computer resolution and mixing it with SD video and recording SD, you need to downrez your computer or crop it to something that fits in the 720x480 SD resolution. You will need a quality scaler to downrez your computer to video. This is sometimes called a scan converter. Quality matters A LOT when it comes to text. A decent scan converter will cost hundreds of dollars. I've used an Extron in the past and found it quite good. Consumer scan converters for analog TVs (pre-digital) were not so good.

There are a few HD Mixer / Switchers that are fairly common from Edirol, Panasonic and Grass Valley.

I'm currently using, and know a few people with the Edirol V-440HD. It an analog HD mixer so the inputs are Component and RGB (VGA).
It works amazing!

On the used market, you're still talking in the $7-10k range for a V-440HD

A few customers have switched to newer cameras with HD-SDI and are in love with the new Panasonic AV-HS400 Learn about Panasonic's AV-HS400A

The big reason is all digital - HDSDI in's and out with DVI too! Resulting in a beautifully clean signal, especially over long runs. The other cool feature is that you can use one huge monitor, say a 42" Plasma and gang all your Cameras on 1 screen. That makes it easier than lugging around or buying a bunch of monitors.

Here is a video where I use the V-440
YouTube - Our new HD Studio - how we do it.
And an older video with a standard def mixer
Edirol LVS-400 and V-4 Video Mixers

One more option if you do not need to do totally live, and only have two cameras is to add two Blackmagic Intensity Pro cards to a computer and use On-air. That's just $199 per card and it's a recorder. You can feed component or HDMI into those.

Guy,

If I used the Edirol LVS-400 and connected two hdv cameras to it, would I get the same 16:9 aspect ratio but 720/480 resolution? If I also connected a computer to the switcher as a third input, would I need a separate scan converter to downrez its resolution as Les Wilson suggested on this thread?

If I used the Blackmagic cards and On-air, could I switch between the two cameras and a computer source (such as video clips in windows media or quicktime that are opened on the same computer that is running On-air)? Would having two firewire ports work, or are the cards with HDMI/component necessary?

I'm a bit confused with all this but I believe I'm almost there.

The LVS-400 is Standard definition and offers S-Video as well as BNC inputs in a 4:3 aspect ratio. There is a newer mixer by Edirol with a built in scan converter Edirol V-8 Video Mixer - it is also 4:3.
On-air only works with two Intensity Pro cards via HDMI or component. If you want Firewire, hmm.... if this is just for web use, have you seen Telestream Wirecast - Overview and the http://www.newtek.com/tricaster/

1. Are there any SD switchers that output in 16:9 in the same general price range of 1-3K?

2. If I use On-air with the Intensity Pro cards, would I be able to integrate, as a video source, a computer (screen) itself? So, in On-air, would I be able to have 2 video camera inputs and one additional computer as a third "camera"?

To clarify,

I'm looking for a piece of software that will allow me record a multicamera production with several mics, where I am able to switch between two cameras recording in 16:9 HDV, and ideally also a third source, which would be video clips from a computer, and simultaneously record audio output from an audio mixer.

If anybody has had experience with Blackmagic Pro Intensity Cards and the On-air software, or any other possible solution to a multi-camera HD production, please respond!

Panasonics AGMX70 is a very good one with 16:9 SD output (SDI out option can be used with Blackmagic card). You can find a used one for under 3K.

Clarification
 

It seems to me that this thread is suffering the same dilemma of "what camera should I buy" and what mic should I buy" type threads and some clarification would really help here. So with that in mind I would like to ask some questions here. I will note the answers as i perceive them so please correct me if I am wrong.

1. Why are you switching live instead of editing multi-cam? Different switchers serve different needs. Are you outputting live to projectors, live broadcasting, webcasting, trying to provide instant DVDs, avoid editing after the fact, or...

2. What is your budget? (1-3K?) Is renting an option?

3. How many source signals are cameras and what models are you using? (HDR-FX1 noted in thread)

4. What is the purpose of the computer in the chain? Are you feeding in slides like powerpoint or just prerecorded video clips? If only video clips, do you have access to a deck so you could cue the clips from tape?

5. What format are you hoping to output from the mixer? HDV? SD? 4:3? 16:9?

6. Will you be recording tape in the cameras or only recording the master mix?

7. Audio. What kind of audio support do you need? XLR with phantom power for separate mics? Individual audio streams from the cameras? One master audio stream from an audio mixing board or direct box?

I think if you can clarify these points we might be able to help with more targeted responses. Thanks!

Bryan,

1. I am trying to switch and record "live," although the final product will not be shown live. It can be tweaked in post, but editing should be kept to a minimum.

2. The budget is 2-5K.

3. There are 2 cameras in the chain, and both are Sony HDR-FX1 cameras (no genlock).

4. The purpose of the computer is to output prerecorded video clips; I do not have a deck.

5. 16:9 HDV (or theoretically, using On-air, maybe uncompressed HD.

6. This depends on whether the workflow works, or whether we'll have to do editing in post.

7. The audio that will sync with the video will be a master stream output from a mixing board.

I have all but abandoned the idea of doing this with a mixing board, and I'm trying to figure out exactly how On-air, using Blackmagic Intensity pro cards, or another software/hardware solution of this sort, would work.

Here is an article that may be of some interest to you:
Choosing a Video Switcher - From VideoMaker.com - article 12581

I have had limited experience with switchers and have found (for me) it is generally better to rent them because I do not switch live very often. I have worked on a Panasonic switcher (can't remember the model number) and a DataVideo SE-800 but in both cases the mixers operated in SD.

My memory of the FX1 is that it does not have HDMI, is that correct? In order to run 2 of these I am guessing you are planning on running 2 Intensity cards, yes? I have not used an intensity card myself but had a project last year that had me looking at them intently. What i found may not apply to your scenario but I hope it helps... Some issues to take into consideration.

The cards are very finicky about system configuration. For best results do not deviate from the list of supported motherboards and system specs ( Blackmagic Design: Support Detail - from BMD website: support FAQ )

You may have already found this but the user manual can be downloaded (in PDF) from their website at this link: http://www.blackmagic-design.com/dow...sityManual.pdf As best as I can tell, On-Air only supports 2 camera inputs (using 2 intensity cards) which would mean adding all your pre-recorded clips in post. It does allow title overlays on a virtual third input but only 2 video inputs.

The Uncompressed HD is an awesome feature but the file sizes are massive and you need a pretty powerful system to handle it. (The manual has a rough comparison chart of formats and resulting file sizes.)

I had a long chat when I was looking at the intensity with a fellow DVi member who uses it pretty exclusively for live capture and he had some great advice. I will see if I can find that thread for you.

The Sony HDR-FX1 does not have an HDMI output; only component. If you can find the thread that discusses the intensity cards that would be great.

I was recently told that Blackmagic no longer has the On-air software on their products page, and I can't find their contact info to ask about that. Obviously if the On-air software has been discontinued, I need to either get an old version of it or find another software solution.

I've been looking into the Wirecast software, but I am unsure right now as to how professional the results will be. Does anybody have experience with it or other switching software?

I did notice that the website does not mention On-Air anymore, but it is still in the downloadable manual. You can check the website at http://www.blackmagic-design.com .

I am still hunting that thread...if I find it i will post a link...

Having done dozens of these types of shows myself, both as an engineer and TD, if you can rent from a good AV Rental house is the way to go. Getting a switcher and a 'scaler', (often referred to as a video or scan converter) from the rental house, usually a Sony 1024 or an Extron box would be an easy and dependable choice. Add an an audio mixer, voil'a. Explain what you are doing, that's IMPORTANT, if it's a good rental place, you should be well taken care of.

The signal flow goes like this, camera via S-video or component to switcher, computer to Sony or extron box via a vga cable, then out converter box to switcher via S or component cable. All audio to an audio board. Output of board and switcher to video deck. Ask for a switcher that can handle S-video or component, composite video is to be avoided if possible. Also, if the video converter has sizing and position controls, if your computer video is not full screen, those controls can help with that.

There are 'cooler' options, but trying to figure out how/if they'll work, especially on-site can be disastrous. SD video is cheaper for gear rental and is most likely going to be the distribution format anyway. And it's rare that the extra quality/detail of HD will add much to this kind of "Talking Heads w/Legs" kind of show anyway.

A/V rental houses should give you good instructions on set-up and if you need crew, a lot of operators, TD's etc., will know how to work this gear. One caveat, implied by some of the above equipment recommendations-make sure the switcher will internally sync the cameras, they have a 'frame buffer'. That means that neither your switcher or you cameras need external sync. Check with the rental guys to see if your video converter does need sync and where to get it from the switcher(usually 'Black Burst' or 'BB' out).

And make sure you get the cable you need for all your hookups. Long S or component cables for video cameras as well as short cables for the converter. Also, long enough mic cables if you are using your own, and don't forget audio adapters, especially if you are using the house audio feed, to go from XLR, or 1/4" TRS Line or Mic level, or RCA line level to whatever your audio board and/or video record deck needs.

Bit of a list, but that's why you get the big bucks. BTW, the switchers and converters will probably be in the $2-300 range to rent, YMMV. Good Luck

Eric,

Your recommendations and explanations for the equipment involved in an SD live switching production are excellent and well-received. My only quibble is the bit about renting! I am planning on being involved with a production of this sort that will be shot once a week, and at 2-300 a week, in a very short amount of time, buying this equipment would make more sense.

My main requirement for the switcher is that it handle at least 3 sources, and be able to output in 16:9 (but not HD of course, as this thread has convinced me that that is out of my price range).

Could you, or anyone else, recommend switchers and scalers in the 1K-3K range?

One additional question: Even when the switchers have "frame buffers," do the cameras you connect to them have to have black burst out or any such thing (obviously not genlock)? I am using Sony HDR-FX1 cameras.

Frame store synchronizers DON'T require cameras to be genlocked or otherwise sync'd BUT they impart a SLIGHT delay before beginning your transition (whether a cut or dissolve or wipe), which varies from unit to unit. My old Videonics MX-Pro was nearly half a second from hitting "take" or selecting a new output hot on the output buss whereas my Edirol LVS-400 is much quicker. This may cause issues if you don't anticipate the time to sync when directing cameras as one operator may think he/she is clear and move while the transition is still in... um, transition.

As well, 16:9 switching is identical to 4:3 in SD. It's at the display end that you need to worry about it. Preview monitors and display monitors will show images however they are told to. Recording a 16:9 stream switched 4:3 to tape or computer isn't a big deal: just make sure to "tell" the DVD authoring program what aspect the anamorphic footage is.

Didn't realize you wanted to buy... I'm used to a certain level of equipment, not trying to sound snobby, it's just 'where' I work, in big halls. So I'm not familiar with gear in your range, with the exception of the FX1, one of which I own. However, looking around, the Edirol/Roland V8 switcher sounds like a possibly very good choice. Handles both analog video and has a vga input with scaler. You might want to find reviews/user comments on that box. I've never used it. As to 16x9 v 4x3, SD video is 4x3, HD is 16x9 as spec'd. So letterboxing or dialing the fx-1 to DV 4x3 is probably your best bet.

Also, as to Shaun's comment about the lag in switching with 'frame buffer' type switchers... On the cheaper Panasonic and Sony switchers I did indeed find a lag if I switched from one cam to the next -on the same bus. The lag was caused by the frame buffer for that bus trying to re-sync to the new signal. If I switched from bus to bus (and thus, frame buffer to frame buffer), I didn't get the lag. I cannot comment on the Edirol, but it is likely it works the same way.

There are some Kramer, TV One, Knox and other multi-format switchers also in your price range. I don't know if you can do dissolves with all/any of them and some output only hi-res video, not NTSC. So check their specs!

I would not recommend the Sony 1024, there's a 1 sec freeze on the image when you switch from PC to camera. Extron would be much better

I still don't understand the issues regarding aspect ratios.

If I connect 2 Sony HDR-FX1 cameras to the Edirol V8 mixer, or a similar product, do I need to select the DV (in 4:3) mode, which is a huge downgrading of quality on this camera, or can I keep the HDV 16:9 setting, which will be downrezed when output from the mixer, but maintain the aspect ratio?

Not if you're switching composite it's not. PLUS you gain 1 to 2 stops of light by doing so. Recording to tape, you see a huge difference. By the time you get to a composite out downconverted, all things are pretty equal. I know, I do this as part of my business model.

16:9 in SD is strictly a pixel aspect ratio change. If you read my above response, you have all the info you need.

Natan, if you keep the FX-1 in HDV it will downrez the video out of the composite and S-video outputs as letterboxed. You get the 'wider' looking picture, but much of the SD 4x3 frame is taken up with black on the top & bottom, i.e. letterboxed. If you shoot in DV, you get the same frame w/out the letterbox. Either way, it's still 720x480. The one advantage of shooting HDV is that in that mode, you do have HDV on tape as backup.

Some of these decisions as to recording format, HD v SD, 16x9 v 4x3 are determined by the specifications of the gear and your decisions around this are going to have to be based on your and your clients needs. In much of what I've done, recording the shows has been secondary to 'i-mag', or image magnification. Putting the video and computer images on big screens live during the event. So video is switched in SD and uprezzed to 1024x768 or higher and a second switcher switches between the video input and computers. Recording is often secondary. All this to say that different clients/situations emphasize different needs.

At your price point, 4x3 SD is probably what your going to both be able to afford and most likely your best distribution format anyway. So make good use of the 4x3 format, embrace SD ;-)

And, if your client(s) want more, i.e. HD, they can pay more...

BTW, NewTeks' VT5 and Tri-Caster, at higher price points, might be worth a look if you get a bigger budget down the line. You can switch, up & down rezz, record and have digital playback all from the same unit. And I believe they will be offering an HD version of at least one of these boxes soon. I checked out a VT4 once and the video looked very good.

Shaun,

So the bad SD quality that I have seen when recording footage from the HDR-FX1 onto tape does not correspond to the quality it would have if I sent the dv stream via composite or s-video to a switcher and then onto a deck or computer?

Can one send SD footage through component cables? As a corollary, do SD switchers tend to have component, or only composite and S-video?

In your price range, composite and S-video. There is component in SD and the FX-1 can offer it via a menu selection, I believe. But in your price range I doubt you'd find the kind of component switcher you are looking for available.

As I said earlier, use S-video , not composite; composite degrades the signal, especially strong colors, too much.

Natan: first, remember you aren't sending a DV stream out the analog outputs, you're sending the signal from the DSP BEFORE it hits tape (and DV compression). You'll need to plug your camera into a monitor and see what the actual output looks like and whether it meets your needs in DV mode.

In response to Eric's post: yes, S-video will provide superior quality HOWEVER the wires used in S-Video cables are typically 28 gauge and there are four sets of braided conductors in there. IF THERE IS ANY POSSIBILITY of your cables being stepped on or having chairs placed over them or being rolled over by carts DON'T EVEN CONSIDER using S-Video. At best you'll end up with a non-functional cable, at worst (this happened to me in a live switched shoot where I couldn't change cable for 5 hours!), the image will short out and go inverse in chroma. BAD BAD BAD!

If you can hide your cables AND you're willing to spend the premium on S-Video cables, go ahead. If not, composite is your friend, just make sure to use good quality 75 ohm RG-59.

Shaun makes a good point about s-cables. If it was me, and I was going to buy and then often use a multicam system, I would be tempted to create special camera cables, i.e. 2 regular bnc cables taped together per camera and a 2-bnc to S-video adapter at each end. The BNC cables are tougher and you get less signal loss on longer runs, i.e. over 100 feet.

You get the best of both worlds. For me, the difference in signal quality would be worth it.

I still have question regarding aspect ratios.

If I want to switch between two 16:9 (non-letterboxed) sd sources, are there sd switchers that can output the 16:9 non-letterboxed signal?

My biggest issue is getting the non-letterboxed footage.

What switchers could do this?

16:9 SD signals can be switched by ANY video switcher AS LONG AS all inputs are 16:9 anamorphic. At the projection/display or recording side (actually editing side) you need to tell the display or editor that the material is anamorphic to get i to stretch back out to widescreen.

Of course, your iso, preview and program monitors will look funny if they aren't switchable as well.

Shaun,

Thanks for you the quick response. So does a typical, or reasonably logical, workflow consist of the following?

1. Cameras connected directly to switcher (and a computer connected to a scaler, and the scaler to the switcher).
2. Possibly audio equipment connected to the switcher.
3. The switcher connected a a recorder of some kind, possible a hard disk recorder?

Am I missing any necessary elements?

My flow is:
- Cameras/scan converters/playback devices/graphic devices attached to iso monitors
- Iso monitors looped through to switcher inputs
- Switcher preview output to preview monitor
- Switcher program output 1 to recorder
- Switcher program output 2 to program monitor
- Recorder output to separate monitor

Audio:
- all audio sources routed to an audio console and mixed "properly"
- audio output of console sent to recorder
- Recorder audio sent to record monitor for verification

The only REAL problem with this et up is that if one starts adding TOO much in the paths, you can begin to introduce signal delay between the audio and video (although in my experience, it's always been tolerable or non-existent)

Of course, this can get far more convoluted when one starts adding in multiple mix-effects busses, several upstream and downstream keyers, graphics units that generate their own alpha channel etc.

I do several events a year using my own setup as above with great results. Barring cameras, my setup is currently in a 10 rack unit case but I'll be breaking everything out into 2 smaller cases shortly.