PDA

View Full Version : Video Delay in VT[3]



David Oliveira
12-02-2004, 03:45 PM
We have a VT[3] delaying the video passing through. It is difficult to measure (in frames) how much is the delay, but it is enough to cause an "out sync" situation with the sound (which is not passing through the board).
We are using the VT[3] just to add GC in live operation...

I have heard that this is being caused by the VT buffers...
The funny side of the problem is that old VT running in an old Amiga platform does not have any delay.

Does anyone have experienced the same problem with the VT[3] ?
Is there any preference that can adjust (or reduce) this ??

wvp
12-02-2004, 05:46 PM
The delay is caused by the video being digitized.
You either need to send the audio mix through the toaster as well as the video or you need to send the toaster video output to an input on an external switcher.

Do a search on this board and you will find other discussions about this (but with the same conclusions)

Jim Capillo
12-02-2004, 09:25 PM
We have a VT[3] delaying the video passing through. It is difficult to measure (in frames) how much is the delay, but it is enough to cause an "out sync" situation with the sound (which is not passing through the board).
We are using the VT[3] just to add GC in live operation...

I have heard that this is being caused by the VT buffers...
The funny side of the problem is that old VT running in an old Amiga platform does not have any delay.

Does anyone have experienced the same problem with the VT[3] ?
Is there any preference that can adjust (or reduce) this ??

It's normal...... there is a delay within the A>D, D>A conversion of just about any video production component. Some are more noticable than others. Actually, as I remember, the OT (Original Toaster) did have a delay if you had a digital effect loaded - do a straight cut or dissolve and there was no delay.

I could be wrong about this, however...... :eek: :D

It really depends on what equipment you are using with the VT. Projectors add considerable delay. Camera delay can be minimized by genlocking them together.

Give us your equipment list and what enviornment you are using the VT in. There are a bunch of talented tech heads here who will help you minimize the delay.....

tonsofpcs
12-02-2004, 11:16 PM
From what I remember, the average delay is something around 400ns, we had audio/video delay lines in our studio (where I work) until we moved completely to the toaster for post (id est not inserting linear on-the-fly)

podro
12-06-2004, 09:06 AM
I have had a 4-5 frame delay with our vt3. we use it in a live imag situation. we just added two new awesome Barco RLM 5 DLP projectors, and the delay is now at 6, and is very very bad. During music, when people on stage are clapping, it's delayed, and the people in the congregation don't know if they need to clap with the screens, or the live music!

I'm considering upgrading to the vt4 for the alpha channel output into our grass valley 110 switcher.

Jim Capillo
12-06-2004, 09:09 AM
I have had a 4-5 frame delay with our vt3. we use it in a live imag situation. we just added two new awesome Barco RLM 5 DLP projectors, and the delay is now at 6, and is very very bad. During music, when people on stage are clapping, it's delayed, and the people in the congregation don't know if they need to clap with the screens, or the live music!

I'm considering upgrading to the vt4 for the alpha channel output into our grass valley 110 switcher.

What are you using for cameras ? Are you using CCU's ? If not, do the cameras have genlock capabilities?

podro
12-06-2004, 09:12 AM
What are you using for cameras ? Are you using CCU's ? If not, do the cameras have genlock capabilities?


4 DSR 390's
4 CCU D-50's genlocked
I switch using the 110, and take the composite into the toaster.
I have the genlock card for the vt3, but when i got it to lock, i didn't see a reduction in the frame delay.

Jim Capillo
12-06-2004, 09:56 AM
That's why you're getting so much delay. Each piece of equipment is creating its own delay. The delay at the 110 is probably small, but by the time the output comes out of the 110 then onto the VT, then onto the projectors, you have a pretty big delay induced.

Not knowing your level of expertise, I'll run through the genlock procedure.

Gen out from the 110 (I assume) to the CCU's. All CCU termination off. Loop genlock thru all the CCU's (1 to 2 to 3 to 4), then gen in to the VT. I didn't have the genlock daughtercard so I don't know the configuration, but if it has a gen out, make sure it is terminated.

One other thing to try is to lock the 110 to the VT. Gen out of the VT to gen in on the 110, then on to the cameras. If you have the cameras locked to the 110, this may help.

alexxi
12-06-2004, 12:11 PM
I have had a 4-5 frame delay with our vt3. we use it in a live imag situation. we just added two new awesome Barco RLM 5 DLP projectors, and the delay is now at 6, and is very very bad. During music, when people on stage are clapping, it's delayed, and the people in the congregation don't know if they need to clap with the screens, or the live music!

I'm considering upgrading to the vt4 for the alpha channel output into our grass valley 110 switcher.

Barco has a 1 Frame delay, this is normal even on the expensive DLP-projectors
110 Grass Valley delay is negligible (1 or 2 Lines)
VT3 under best alignment has 3 frames (this is normal). Only connecting Genlock does help for direct switching on program(but still 4 frames). To deny one additional frame you have to adjust the sync/phase exactly with an external Waveform and Vectorscope.
Maybe you can deny another frame if you change your setting "switdelay" to "0", [default is "1"] in the "newtekrtme.cfg" file.
(You have to kill the "winrtme" process for taking effect)

bg
alexx