Use-Cases

LTC synchronization in action

The other day we received feedback from a client who used LTC synchronization at a large event.
The professionals from Dropin-tv.de used synchronization by sound to broadcast a large scale event from the mountains. Manuel kindly described us a scheme of how it works.

A little bit about LTC

There are several ways to transmit timecode during broadcasting and one of these methods is to transmit via sound - LTC audio. It sounds like a crackling sound.

Transmitting timecode as an audio track has obvious advantages:
  • It does not depend on the video codec. It can be used with any video codec while transmitting timecode via SEI is only provided for h264 and HEVC (SEI method)
  • It can be easily added to encoders that do NOT support timecode generation. For example you can add it to GoPro and LiveU encoders. All you need to do is to apply the appropriate signal to the audio input.
SRTMiniServer can read such audio and synchronization between cameras is performed. Given the capabilities of SRTMiniServer 2.5 it can be done both with SRT and RTMP streams.

Feedback from Manuel (Dropin-tv.de)

I’m writing to share insights about our recent workflow using the SRT Mini Server at one of Europe’s largest snowboarding events and to discuss planned improvements and upcoming projects where we see the SRT Mini Server playing a critical role.

Event Overview

We recently supported one of Europe’s biggest snowboarding events, featuring Slopestyle and Halfpipe competitions over the course of a week, from qualifiers to the finals. With a highly dynamic and challenging environment, we utilized the following workflow to manage our live production needs:

Workflow Details

Camera Setup:
  • We deployed more than 6 cameras on the mountain, all capturing 1080/50p video.
  • Tentacle Sync devices were connected to the audio channel 1 of each camera signal to generate LTC timecode.
Signal Transmission:
  • All SDI camera signals were routed into Teradek Prism Backpacks equipped with 6 LTE modems for bonded transmission.
  • The bonded signals were sent to Teradek Core Cloud, where we accessed individual camera feeds via SRT streams.
SRT Mini Server Integration:
  • The SRT Mini Server was used to receive and synchronize the SRT streams from the Core Cloud.
  • While synchronization was effective, we encountered delays of around 10 seconds, which was manageable during the week but became a challenge during the finals.
  • For the finals, we opted for direct SDI or wireless links for critical camera signals while using SRT for Red cameras dedicated to slow-motion shots, where sync precision was less critical.
Production Workflow:
  • Signals from the SRT Mini Server were output via SDI/NDI to our TriCaster Vizion system, where they were combined into the program output (PGM).

Check out the playlist this explains the setup
https://youtu.be/OFWtuBPjhDQ?si=Lg3a-z1ozktIMxR_

Conclusion

Synchronization of several cameras is an important aspect in sports broadcasts.
Sound synchronization using LTC generators and SRT Mini Server allows you to do this with any cameras and encoders.
How-to