RP-NDI-AUX-TC_2024_11

proposal for carriage of Auxilliary Timecode information in NDI

This page contains a technical proposal which is not currently a published or formal standard. If you have comments or feedback on the content of this proposal PLEASE contact us with your contribution.

 

This proposal defines a standardised wrapper to carry auxilliary timecode over NDI by way of a recommended practice technical note.

 

Basic Premise:

NDI already carries Timecode in its Video and Audio Packets, but there is only a single timecode field in each packet. In some cases there may be a need to carry an auxilliary timecode along with the primary timecode.

This can be used when converting SDI signals which carry multiple timecode sources, or it could be used for something like a countdown timecode, which shows remaining time, or elapsed time for a given stream - for example playback of media, or an action replay

 

Video-Frame Attached Example

In this proposal, the metadata is sent using the NDI per-frame metadata messages attached to discrete video frames which is already defined in the NDI Protocol.

 

 

Example :

ndi_video_frame.p_metadata =

<ndi_metadata type=”AUXILLIARY_TIMECODE” version=”1.0.0″>

     <label>LTC</label>

     <timecode>13453466568678</timecode>

</ndi_metadata>

 

The timecode field uses the standard NDI 10,000,000 units per second - since the Unix epoch to represent time. The same format as the standard timecode and timestamp fields in NDI.

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