Frame Lag Introduced by the AF-100?

B

brookstomlinson

Member
Hello all.
I'm a happy af-100 owner. I have a small hd ac7, and just got a samurai blade. When I was doing some test shooting, I noticed there was a frame lag while panning. So when I got back to the shop, I did timecode frame capture, showing the original source, the Af-100 monitor, and the Samurai and the AC7.

Here is what I found out,
Source to Af-100 - 2frame lag
HD-SDI to AC7 - 2 frame lag (4 total)
HD-SDI to Blade - 3 frame lag (5 total)

I also did the same test using my Blackmagic Studio Express
Source to AC7 - 0 Frame lag
Source to Blade - 1 frame lag.

So it looks like the blade introduces one frame of lag on it's own.

So the Af-100 is two frames behind on it's own, and then adds another 2 frames to the HD-SDI out?

Am I doing something wrong? is it a set up on my end? or do I just need to find an HD-SDI inline flux capacitor?


Brooks
 
I dont understand what you mean by frame lag or how and where you are seeing and measuring it.
 
Okay, no problem. To clarify,

On my laptop in after effects, I make a comp that creates a red frame every 5 frames.

I point the af-100 at the laptop.

I attach the Small AC7 via HD-SDI to the Af-100

I have a camera pointed at the screens of the computer, af-100, and the small hd AC7, then I record it. (so the camera records all three screens)

I then bring that footage into an editing program. Once in the editor, I see the red frame come up on the computer. The AF-100 screen is black, the AC7 is black. Move one frame forward on the timeline of the editor, all screens are black. Move one more frame forward on the editor time line (a total of 2 frames) and the Af-100 screen is now red, but the AC7 is still black. Advance another frame (3 total) all screens black. Another frame (total of 4 frames) the AC7 is now red, and all other are black.

So,
frame 1, computer is red. Frame 2,3,4,5 computer is black
frame 1 and 2, the Af-100 monitor is black, frame 3 it is red, frame 4,5 black
frame 1,2,3,4, the AC7 is black, frame 5 the AC7 is red.

that puts the AF-100 screen on a 2 frame delay from reality.
then thru the HD-SDI, it adds another 2 frames, for 4 frames behind reality in total if you have the AC7 attached.

if i use my black magic hyperdeck express to repeat this test. Going out of the HD-SDI to the AC7, it is dead on, frame for frame what the computer is showing.

does that help?
 
The HDSDI has at least a 2 frame lag. If you record your audio on camera, or output through the HDSDI port, you'll never notice the problem. If your HDSDI feeds video to a recorder and the audio goes from mic straight to that recorder, you will have a 2 frame mismatch on your sync.

i don't know anything about your "frame lag". Your test you listed would only work if you could guarentee that you were starting the cameras at the same time.
 
He's test seems right to me, only one camera recording. The OP is simply recording 3 screens with one camera as the control device.

cool little test.
 
XSVpro said:
He's test seems right to me, only one camera recording. The OP is simply recording 3 screens with one camera as the control device.

cool little test.
Click to expand...

Thanks, but I picked up the idea from the blackmagic fourn guys. But they used a still camera an ipad with timecode. I had two video cameras Available so I thought it would be easier to record it.

I'm a little disappointed about the 2 frame lag from the hd-Sdi
 
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