Mini convertor latency

Does anyone know the exact latency of the mini convertors (I have the analogue to SDI and SDI to HDMI)?

I know there is some but I dont have the gear with me to decide on preparations for a job. Also does anyone know of any SDI to HDMI convertors with no (I know not possible) to minimal delay- suitable for live use?

Fred

The conversion from sdi to hdmi and the other way should not add any noticable latency.
Only thing that happens is it goes from a serial signal to a chopped up (multiplexed) signal over 4 twisted pairs or the other way around when you go from HDMI to SDI.

I go out the analog components of my JVC HD200 cameras into an Analog to SDI, into an ATEM 1 and I'm 2 frames latent in 720P60, I attribute 1 to the converter and one to the ATEM "frame sync".

[Chris Pearse]

Hi Fred

The Mini Converter SDI to HDMI has a delay of less than a single line of video, except when it needs to convert PsF to P, which will take one frame. The Analog to SDI has a four line delay.

Thanks everyone for your answers, now I have to look elsewhere for the delay.

Cheers

Fred

The Analog to SDI has a four line delay.

Are you sure about this?

I have tested these and concluded that it adds lines rather than frames for Analogue to SDI.

I was told that it is the UpDownCross converter that add 4 frames of delay.

Tim

[Chris Pearse]

Hi Tim,

This was the information provided to me by the engineers. As far as I am aware, the Mini Converters that convert between SDI and either HDMI or Analog will never take more than a few lines to convert. Typically I think the only time we're really taking more than a frame to convert is when we're performing some kind of framesize/rate conversion. For example with the SDI to Analog or HDMI to SDI with processing enabled (I don't have a figure for this I'm afraid), or the UpDownCross, which will indeed add a few frames delay.

I have tested these and concluded that it adds lines rather than frames for Analogue to SDI.

Isn't that exactly what he wrote?

The Analog to SDI has a four line delay.

I have tested these and concluded that it adds lines rather than frames for Analogue to SDI.

Isn't that exactly what he wrote?

The Analog to SDI has a four line delay.

Apologies.

In my head I read that as four frames delay.

It must be that the latency between my eyes and brain was quite high yesterday

Sorry for any confusion caused.

Tim

No worries I just wondered if it was me who missed something.

When hunting for latency don't forget that the camera adds 1 frame to the path.

In the days of tube cameras and tube displays a beam scanned the face of the pickup tube and that modulated the signal on the wire that then modulated the beam scanning the phosphor of the CRT.
(a very simplified description) That means there is only wire delays in the path so the timing seen on the monitor is as close to realtime as we can get.

With the advent of chip sensors the photosites have to absorb the light for the frame time and then transfer that charge to the matrix to be scanned out onto the wire. That means that the signal on the wire is 1 frame later than the light hitting the sensor. When that signal gets to a flat panel monitor it has to get fully buffered before it is displayed, that means the light emitted from the display is a minimum of 2 frames delayed from the light that hits the lens.

Toss in a frame sync device or some sort of conversion and more frames are added to the delay path.

Your existential question for the day is: What is real time?