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IDProjectCategoryView StatusLast Update
0005909ardourbugspublic2014-04-16 01:39
Reporterunfa Assigned To 
PrioritynormalSeveritymajorReproducibilityrandom
Status newResolutionopen 
Product Version3.0 
Summary0005909: LTC timecode signal disappears when transport starts
DescriptionI'm running Ardour3.5.308~dfsg-1 (built using 3.5.308~dfsg-1 and GCC version 4.8.2) under Ubuntu Studio 14.04 beta 2.

I wanted to make some tests with Ardour's LTC timecode functions - I tried to record Ardour's LTC output with Audacity, planning to later play it back and see if Ardour's transport will "replay" it's motion according to captured timecode information.

However the only timecode I was able to get was 00:00:00:00s sent while the transport was stopped.

As soon as I pressed play and my I heard my recorded session, Audacity showed up waveforms of all captured Ardour's output, but the track with LTC timecode immediately went silent, while it was displaying the timecode waveform when Ardour's transport was stopped.

What am I doing wrong? Or is this a bug?

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*Update: I tried again to confirm if it works or not, and it seems to function properly this time.

Here's a video showing the quick test I did:
http://youtu.be/dWeXH4cJrZk

As you can see this time it works.

What can I do if this happens again to help track down the problem?
TagsNo tags attached.

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x42

2014-04-16 01:39

administrator   ~0015746

You've got the LTC "sync locked" option set in which case ardour won't vari-speed.

Hover the mouse over the option in the preference and read the tooltip. It is intended for soundcards that are synced with word-clock to an external timecode generator. Similarly sending timecode while stopped is only recommended if you have a video-player that will unspool the tape if it does not receive LTC. Slaving Ardour to steady LTC will increase the time to initial sync.

Further information is also available at http://manual.ardour.org/synchronization/timecode-generators-and-slaves/

Audacity's jack support is bad at best, it does not honor jack port latencies and due to portaudio's push and buffer mechanism adds some random latency every time you play/stop audacity. It is entirely unsuitable for validation. I highly recommend to use a proper jack application for everything but basic testing.

FWIW, Ardour3's LTC slave and generator have been verified using hardware:
http://gareus.org/wiki/a3extsync#measurements

Issue History

Date Modified Username Field Change
2014-04-16 00:23 unfa New Issue
2014-04-16 01:39 x42 Note Added: 0015746