Kramer VP-728 vs. VP-438? Other switchers I should consider?

T

TJ Cornish

Graduate
Jan 13, 2011
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St. Paul, MN
I'm generally familiar with the operation of the Kramer switcher scalers. Looking at the specs, it seems that either the VP-728 or the VP-438 would meet my needs. Is there any reason I should choose one over the other? They seem really similar, and I'm not sure why the VP-728 is more money.

Any other models in the ~$1000 range (less would be great) that I should consider? My requirements are seamless switching between a couple computers, with the possibility of doing crude IMag using pro-sumer cameras. I'm not sure exactly what this might be used for in the future, so more is better, within reason.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

Silas Pradetto said:
There is somewhat significant latency with the 728/729, enough that I can notice it when panning a camera, so IMAG might not be a good plan for that series.
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Generally any switcher setup that isn't genlocked, but instead using frame synchronizers, is going to have substantial latency. If you're serious about IMAG, then your switcher and cameras need genlock facilities, and even then you may need some audio delay for sync. There are also cases where genlockable video output from your computers is appropriate, but for your typical PPT/Keynote the couple extra frames of delay from non-genlocked input is no big deal.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

Agreed. Latency is a requirement of syncing disparate cheapo sources. I would love a set of ful CCU-controlled cameras and the associated high-end switching, but that is ocean-liner class, and I'm looking for about a 15HP Johnson outboard on a 14' boat.

For the youth conference I just finished, it would have been nice to be able to point a camera at the floor where the students were getting pudding dropped on their faces. That's the kind of level I'm looking for - one notch better than using the video projector's remote to switch inputs.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

I actually found the answer to my original question (calling the Mfr - who'da thunk). The 700 series are "seamless" in that they use a frame buffer to prevent the video glitch. The 400 series don't - switching inputs causes a loss of sync. The positive consequence probably - I haven't tested this) is that the 400 series probably has less latency.

We ended up buying a 700 series.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

Hey TJ. I have virtually the same application, so I am interested in how you found using the 700 that you got. Did you end up getting the 728, and did it meet your expectations? How was the switching speed, and did the latency end up to be significant? Anything else that I should be aware of?
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

Sean Verwey said:
Hey TJ. I have virtually the same application, so I am interested in how you found using the 700 that you got. Did you end up getting the 728, and did it meet your expectations? How was the switching speed, and did the latency end up to be significant? Anything else that I should be aware of?
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Whoops - sorry for missing your post. We got I think the VP-730 - a few more inputs than the 728, but basically the same. It has some latency, but if you're not looking at both the stage and the screen at the same time, it's not too bad.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

Steve Ferreira said:
Is it a seamless switch going from IMAG and say a PC or does the IMAG freeze?
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Not 100% sure what you're asking. The VP-7XX series uses what they call "Fade through black" - the old input fades out, the new one fades in. If you're asking does the IMag frame freeze while it's fading out - no. What seamless means is the projector never loses sync - it doesn't turn blue, pop up a menu, glitch white, or whatever your particular projector does when a cable gets unplugged - what the projector sees is a continuous video source at whatever output resolution you set your VP box to.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

TJ Cornish said:
Not 100% sure what you're asking. The VP-7XX series uses what they call "Fade through black" - the old input fades out, the new one fades in. If you're asking does the IMag frame freeze while it's fading out - no. What seamless means is the projector never loses sync - it doesn't turn blue, pop up a menu, glitch white, or whatever your particular projector does when a cable gets unplugged - what the projector sees is a continuous video source at whatever output resolution you set your VP box to.
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Hi TJ,

I was just asking because some switchers freeze the frame on the IMAG when going to a PC, or a dvd to a PC. Doesn't say on their website but I'm guessing it's a single scaler switcher.
Seamless to me means a dual scaler unit that doesn't need to fade to black and then back up to the next source. Any switcher should be able to produce a signal to the projector to stay sync'd without even having an input source attached to it.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

Steve Ferreira said:
Hi TJ,

I was just asking because some switchers freeze the frame on the IMAG when going to a PC, or a dvd to a PC. Doesn't say on their website but I'm guessing it's a single scaler switcher.
Seamless to me means a dual scaler unit that doesn't need to fade to black and then back up to the next source. Any switcher should be able to produce a signal to the projector to stay sync'd without even having an input source attached to it.
Click to expand...

IINAVG (I am not a video guy), but my understanding is that you have to compensate for the differences in where the frame is being scanned at the moment of switching for non-genlocked sources. In other words, if you don't have framebuffer functionality, the video glitches as the projector jumps to where the input is being scanned. As to the implementation of this - I'm not sure, though check the price of this unit vs other fancier switchers and weigh capabilities accordingly.

If I ever think my audio and lighting gear is expensive, I quickly feel a lot better after talking to my video-head friends.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

I am a video guy :)

Frame syncs themselves aren't the problem, a good one will have ≤1 frame of latency.

In a (common) 60fps system, that would be only about 13ms of delay in and of itself.

The real issue is end-to-end latency.

It seems, in general lay-man terms, like we can tolerate up-to about 100ms of delay before it starts to "feel" off. It will take a bit more than that before it visibly "looks" off.

While having fully locked native-res everything is the sure-fire way to be safe, and has other convinces afforded to it, it isn't strictly necessary for a real-world good-enough scenario.

What really kills you is all the up-down-cross conversions.

Often times, between a slow-to-act presentation switcher and halve a dozen up-down-cross conversations, you practically begin having already lost.

These days I go one of two routes pretty much exclusively.

If dealing with IMAG, I go fully HD-SDI. Computers or other non-SDI sources get "real" converters, cameras must have an SDI output. I don't get overly caught up trying to make sure everything is genlocked on the input side. I then use a native HDSDI switcher with frame syncs and SDI out to native SDI displays.

This way I am not dealing with lag from the switcher to the displays, and can afford to have the lag on the front side and run cheaper cameras or do weird conversions as necessary.

If I am not using cameras I obviously have a lot more play, but will make sure to be using scalers with digital outputs capable of driving my primary displays at their native panel resolution.

It gets a bit more tricky when we need cameras, but also the features of the fancier processors (FSN/Spyder/Etc) or we are driving laggy output devices (LED, non-native displays, etc).

In that case we need to be much more careful, but at those dollar values you can afford to hire us :)

In short, frame syncs aren't bad in and of themselves, I in fact use them as a general course of action, however you need to be mindful of the delay of the entire chain.

Karl P
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

TJ Cornish said:
Not 100% sure what you're asking. The VP-7XX series uses what they call "Fade through black" - the old input fades out, the new one fades in. If you're asking does the IMag frame freeze while it's fading out - no. What seamless means is the projector never loses sync - it doesn't turn blue, pop up a menu, glitch white, or whatever your particular projector does when a cable gets unplugged - what the projector sees is a continuous video source at whatever output resolution you set your VP box to.
Click to expand...
I agree with Steve and personally consider a unit with a single scaler a switcher/scaler. The actual switching between inputs occurs before the scaler so the unit may fade through black or freeze the last frame while the scaler input switches then switch back to the live scaler output. In comparison, I view a seamless switcher as having two scalers with the switching happening after the scalers. With a seamless switcher there is no freeze or fade through black required since both signals are already scaled the same and the switch can be 'live'. With those definitions both switcher/scalers and seamless switchers provide a continuous, scaled Program output, the difference is primarily in how they switch between inputs, 'live' versus fade-thru-black/freeze. One other difference is that a seamless switcher also usually provides a continuous, scaled Preview output in addition to the Program output.
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

Brad Weber said:
One other difference is that a seamless switcher also usually provides a continuous, scaled Preview output in addition to the Program output.
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Also of note, due to the structure of a dual/seemless switcher and as a byproduct of their design, they tend to have less delay in them. To be certain that isn't always the case, and even so the delay varies wildly between different manufacturers and models, but nonetheless a consideration to make.

Karl P
 
Re: Kramer VP-728 vs. VP-438? Other switchers I should consider?

Steve Ferreira said:
Hi TJ,

I was just asking because some switchers freeze the frame on the IMAG when going to a PC, or a dvd to a PC. Doesn't say on their website but I'm guessing it's a single scaler switcher.
Seamless to me means a dual scaler unit that doesn't need to fade to black and then back up to the next source. Any switcher should be able to produce a signal to the projector to stay sync'd without even having an input source attached to it.
Click to expand...

I'm pretty certain the 728 does freeze the video for the fade-through-black. We have several single-scaler Kramers (though not a 728) and all do this.

Sorry - been away a while and didn't note the date on this thread.
 
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