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From: Perry Paolantonio <>
Subject: Dynamically adjust tempo based on a reference track?
Date: Sun, 17 Feb 2019 08:53:17 -0500
Message-ID: <> (raw)


I have a situation specific to audio recorded for motion picture sound. There were a couple of different methods to ensure that audio recorded on a tape deck stayed in sync with the picture recorded on the camera. The two most common were Pilotone and Neopilot. (there are others, but these are the most common)

Pilotone used a 50 or 60Hz tone generator in the camera. The camera was physically tethered to the tape deck, and the tone was recorded on a reference track. Back in the studio, the speed of the audio was resolved to match the picture, by adjusting speed constantly on playback to get the reference tone where it was supposed to be. Worked pretty well. 

Neopilot is similar, and was Nagra’s invention, I think. It used a crystal-governed tone generator to make a reference track on the tape, and the camera used a crystal governed motor at the same frequency. This worked really well, since both machines were running at fixed speeds. In fact, you no longer need a nagra to do this, you can use any digital recorder and sync is dead-on.

Anyway, I’m looking for a way to take a recorded reference track and adjust its speed and the speed of the main track to conform to the nominal referece frequency throughout, while taking the audio along for the ride. In theory, this would allow us to capture the audio from any reasonable tape deck that can play back the tracks separately, without having to deal specifically with (harder and harder to find) studio decks such as the Nagra T, which can do this out of the box. 

Is this possible in Sox? If so, how would one go about it? 



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Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-17 13:53 Perry Paolantonio [this message]
2019-02-17 16:07 ` Bouke / VideoToolShed

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