Blackmagic Forum

Hello admins and community,

This is the question I would like to rise related to a DeckLink device:

Is Output Synchronized with their Input?

To be more specific:
* I refer to a DeckLink device in duplex mode and
* without any signal present in the reference input

From another point of view:

1. What happens when an app is generating an output stream without any input signal present (in his input pair of duplex mode device) and without reference signal in the ref in connector?

2. What happens when an app is generating an output stream with an input signal present (in his input pair of duplex mode device) and without reference signal in the ref in connector?

3. What happens when an app is generating an output stream with an input signal present (in his input pair of duplex mode device) and with reference signal in the ref in connector? (this is easy to answer!)

Thank you in advance,

Gabriel Solsona

Hi Gabriel,

In general, the output will be generated with reference to the internal clock or the reference input (if available and compatible with the output video mode).

The video input does not have an impact on video output timing, and input and output may use different video rates (e.g. it is possible to capture 1080p29.97 while outputting 1080p25).

1. What happens when an app is generating an output stream without any input signal present (in his input pair of duplex mode device) and without reference signal in the ref in connector?

The output will be generated with reference to the internal clock on the device.

2. What happens when an app is generating an output stream with an input signal present (in his input pair of duplex mode device) and without reference signal in the ref in connector?

The output will be generated with reference to the internal clock on the device. The presence of an input signal will not change the output timing [1].

3. What happens when an app is generating an output stream with an input signal present (in his input pair of duplex mode device) and with reference signal in the ref in connector? (this is easy to answer!)

The output will be generated with reference to the reference input (genlock) assuming the reference input is compatible with the active video output mode.

Hope that helps,

-nick

[1] Output video timing will be related to the video input when performing an Internal Keying operation.

Hi Nick,
So, I would like to sync output video timing related to the video input because I want to insert additional info from the app to the video input towards the audio output.

What would be the best API configuration option? Configuring as a internal keying operation?

Gabriel