Reperformance: HDSDI Metadata SMPTE315M

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Previzion Embedded Metadata

As of build 6710, Previzion’s SDI output has all tracking data embedded in its video outputs. This is valid for both SDI outputs and embeds all tracking data, like x/y/z location, tilt/roll and lens information.

The data is embedded in ANC packages in line 10 using SMPTE 315M-2004 format.  The process of utilizing a recorded video with tracking metadata into Previzion is referred to as reperformance.

This feature allows Previzion users to literally bring their Previzion systems into the post-production environment.

Embedded metadata has the potential to change the way current virtual productions deal with their assets and Lightcraft is working on more tools to improve the VFX world.

The actual specifications can be downloaded from Dashboard through this link.

How does reperformance work?

The embedded metadata is frame accurate and is recorded alongside your footage.  Using a supported recorder and your Previzion system, you can replay “foreground” (a clean green screen feed) and set all your Previzion settings with the advantage of having more time to adjust the settings.

With simply the HD video recorder and your Previzion box, you can replay the clean green footage and set your key, load relevant scenes, move cameras, change lenses (if necessary) and so on.

Reperformance, playing back through Previzion, cannot refine tracking afterwards.  It’s most useful when tracking is working correctly and all that is needed is to key, color and/or add mattes.

For more tools and tracking refinements, consider using a metadata extractor in our Nuke pipeline (see Nuke Embedded Data Import).

How can I confirm I am recording the tracking data?

Since the recorders that are able to capture and store 315M ANC data can’t indicate the presence of SMPTE 315M data, the only reliable way to confirm presence of the data is to play it back into Previzion as indicated below in “Recommended Settings”.

Please note that many video converters, splitters and embedders often strip all ANC data, which may include timecode.  In these cases, make sure to bi-pass such devices to ensure the data is being passed through properly.

Supported Recorders

Lightcraft is actively in conversations with various HDSDI field recorder manufacturers to implement support with SMPTE315M and reperformance.

Please reference the table below to see if your recorder supports this feature:

 ** frame-by-frame tracking position may be recorded as ANC with a few frames offset.  This is not usable for “reperformance,” but it’s usable for tracking data extraction.

We are currently working with video recorder developers to add support to this feature, test and implement recording/playback to their specific recorders.

If you are planning on using a recorder and would like to have this feature supported, please contact support (at) lightcrafttech.com and let us know which recorder you are using.
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Recommended Settings

For this setup, we recommend setting the HDSDI output from Previzion to be set to “Foreground” (clean green feed).

 

All you need to do is plug the recorder, like an AJA KiPro, into your Previzion HDSDI IN 1 and set as:

• Sync: Generated
• Location: Previzion Video
• Lens: Previzion Video

• Video Input Format: the correct video frame rate
• HD-SDI 1: Enabled

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