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Hi Braintrust,

I have been trying to send LTC from a Watchpax 60 on an audio track to play a large number of discrete audio files using a pre-recorded SMPTE file. When I do, the file plays "dirty"; I get a lot of dropped frames, and the equipment I am trying to sync (Q-SYS) stutters. I was using an attached Scarlett 820i, but bypassed it for default audio output as a test; no change in result. The audio line is running direct from Watchout to an IO frame with no other equipment in line. I've tried multiple SMPTE files from multiple sources; all have the same problem, and all of them work when I play directly from another source. I'm making heavy use of asynchronous playback through auxiliary timelines, so syncing Watchout to Q-SYS or an alternative SMPTE source isn't going to work in my situation. The file, Watchout, and Q-SYS are all set to 48k.

Is there some larger issue getting SMPTE to output from Watchout, or some trick to it I should be aware of?


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  • Dataton Partner

Have you tried to read the signal with a second computer running the timecode reader software which comes with WATCHOUT? This could give you some indication on the signal quality. I have seen one situation many, many years ago where a lighting console had problems to read a timecode from a file in WATCHOUT. The reason was a very small timing detection window on the receiver side which normally is a bit wider in most devices. The solution back then was to use a Rosendahl MIF3 which was able to read and re-clock the signal.

Since WATCHOUT is constantly re-syncing all player instances of a WATCHOUT cluster you will probably see some tiny jittering in the timing of the timecode signal.

Another option would be to check the signal shape using an oscilloscope. If it looks more or less like rectangles it should be fine. If it doesn't, it will probably fail. The reason here is often some (audio) device in the signal flow which doesn't forward a clean rectangular wave. I have seen isolation transformers destroying the rectangular signal.

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  • 2 weeks later...

LTC playback in WO and interlocking with peripherals is also used in the field.

In my case, I had a similar experience when the LTC signal had insufficient volume or the original level of the LTC was broken due to simultaneous playback with other sources. Or the level is broken because the volume is too high.

Try creating a new separate show to test or control the LTC code in preview mode in a production program.

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  • 2 weeks later...

Just to clarify, I never did find a solution to this. I played with volume levels with little difference. This was tested in a new show file with no change. All the files were WAV 48k 32bit float. All other audio would come out fine. 

I ended up installing additional Scarletts receiving audio through ADAT to expand my analog output to the quantity I required (we had left open QSC amplifier input channels, so I populated there).


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