Multiple DV streams

[chriscj]

Hi all,

just wondering about the ability to capture multiple DV streams simultainously and swtich at the same time. The intended application is a live sports switch environment where all cameras come in on DV (would we need one card per camera or can you have multiple inputs from cars with more than one firewire connector?), be switched, and head out in component for archive.

What we would like is for each input to be iso'd and the program out to be recorded (in DV) at the same time. The premise being that we could quickly line up all the footage after the fact and fix any mistakes from the live switch with the iso footage, all in a very short space of time.

What are the performance limitations on something like this? There is only a short mention of this in the VT3 info and it states "several". We'd be looking for around 4 DV ins plus 4 composite ins plus 2 svideo ins, switched and recorded to DV. The analog inputs would either be iso's to tape prior to the VT3 or would just be thrown away (just want to make it clear that I'm not trying to iso analog signals in DV).

Thanks in advance,
Chris

P.S. Paul, is NewTek Europe showing up to IBC this year?

[wvp]

You can connect 4 DV sources (or more) into VT[3]. You can do this with a mutli-input firewire card. Four input cards are pretty common, there is also a 6 input card (see my reply in the hardware section (I think) - do a search for "firewire card"
For iso, you will want to do that in the camera.
In addition to the DV out, you need to connect an analog out to a monitor [for all sources] (you can only see what is on preview & program in the toaster).
You can record your switch to the harddrive or output to an external deck (or both). If to harddrive, the faster the drives, the better. Also for live switching I would get a dual xeon system with 1gb of ram.

[PIZAZZ]

Just wanted to make sure...

You are not planning on putting the switched final up on IMAG/Video Screens are you?

Mixing multiple DV streams has a certain amount of latency involved. Mixing DV and analog sources could have some issues too if say you are using 3 cameras with DV in and 2 Cameras with analog in.

As a person that does a ton of live switching, I would NEVER trust those little DV plugs to stay in at an event. Definitely not going to bulletproof if you are shooting sports unless it is maybe chess or badminton.

What cameras and also more importantly what cables are you planning on using. There is a limit on how far a DV signal can travel safely. I have used and seen the longer DV cables and I just wasn't happy so I went back to SVHS analog and saw no big difference in quality. This is when we use Canon XL1s or similar. For our larger shows we use Sony D35s with CCUs and go component into the SX8.

If we use XL1s or DSR570s, we use the DV output to iso the cameras into a Videonics Firestore at each camera position. We save the cost of ISO tapes and drastically speed up any fixup edits we might have to do.

Just some thoughts and experiences.

[chriscj]

Jef,

Thanks for your response. I'm still curious about recording the multiple streams which no one seems to have touchedo n yet.

In response to your post, we are toying with this as an idea at present and thus all feedback is extremely useful. I'm not overlly worried about the connectors - we're talking fixed camera positions and I'm sure one of our guys can rig something to prevent that problem. As for the cables, we were looking at Laird's DVistance cables, but I'll take a good look at the signal through them at IBC to make sure.

What does worry me is your comment about the latency. Do you mean it's worse than with analog (about 1-2 frames). What about if you switch properly via the preview bus/take? How long does the TBC take to sync up? The reason for the mix is our lipstick cameras only have composite outs.

DV in is only one of the options, I'd prefer a wireless system as all our talkback is wireless and it would make deployment so much easier.

The key thing that I was interested in was the ability to record multiple streams - and as I understood it, DV would be the way to go since you can only have two analog sources at a time. What I'm really after is a way to live switch, and by the end of the swtich have at least one or two cameras that were iso'd directly on to the drives that could be used to fix things or for cutaways or slo-mo rather than doing those live.

Our system is a dual 2.4Ghz Xeon with I think 1.5Gb of RAM.

Take care,
Chris

[PIZAZZ]

Answers to your questions are yes, no, and maybe.... ;)

I would love to say with complete conviction that YES the VT[3] will do all of what you ask for. I just can't though. I have only been able to get 3 DV streams to record simultaneously. We are ONLY running a Dual 2.8ghz with 6 73gig Scsi drives and 2 gigs of Ram.

Because we are both a live event production company and also a Newtek Dealer, I tend to be a little more objective about what I expect 1 box to do. I see advantages in redundancy. I have had SCSI drives crater on me in the field and I if I had everything on that array then oops!! hozed for that show. That is why we try to only scale our equipment to the importance of the show. If it is a one time take, we take every precaution available to implement a backup at every turn. If the show is for example an IMAG event that will never be posted or aired then we don't worry about all the extra junk and travel light.

I like the idea of DV to hard drive a great deal. We are trying to go this route more and more. That is why I suggested using the Firestore as your direct to hard drive recorder. This overhead would be separated from your live switcher and the footage would be still just as quickly usable if you needed to edit after the show.

I understand you are just researching now but be warned the DV 4pin connector is not designed for frequent use. I have had a DSR20 deck and an XL1 both repaired because the jacks wore out from use. The repairs were not cheap either.
The Laird DV cables are similar to the ones we have sold from Videonics. I had a customer with a MXPRODV mixer and insisted on the long DV cables. I tried them out with him and we just weren't that satisfied with the visual quality difference enough to justify the cost of the cable.


As far as Latency,
Analog inputs can be brought down to 2 frames if all the inputs are genlocked together. DV inputs (because of the decoding of the digital signal) tend to be around 7-9 frames sometimes more. That is why I asked if you are going to IMAG screens or not. 2 frames is acceptable but 8 frames to the untrained eye just looks wrong.

If you really want the best of both worlds then I have a suggestion for you. Buy 2 VT[3]s. One would be for your live switching and 1 stream recording and the other would be for 2 other streams and a backup.

This is how we have switch several shows including one for CARA at the INDY 500. Redundancy is a good thing out in the field.