What is TC for?
If you use pro audio gear, or even just a simple external recorder, it's a massive time saver to have a master timecode clock.
For example - although ML has greatly improved the existing audio capabilities of canon cameras, it's still not that great. A step up is to use an external audio recorder - an ok one will give you decent mixing control, xlr inputs with phantom power etc meaning you can use boom mics, radio mics etc. You can also have huge multi channel setups where you might have up to 16 radio mics plugged in to a hard disk recorder. This is all very good but without a means of synchronising this audio with the video it all gets very time consuming when it comes to the edit. You might also have several cameras which all need to use the same timecode clock but that's another story.
Timecode can be encoded into an audio-compatible track and recorded on any device which records audio. A pro camera usually has a socket marked LTC out and whichever timecode the camera is using, be it a preset timecode or 'time-of-day' timecode is generated and 'played' through this device. You plug this into your audio recorder on a spare channel and then you've got a rock solid frame accurate sync track for use in editing.
I use avid and if theres an LTC track on any of my audio feeds I can just click 'read audio timecode' and auxiliary timecode tracking info is made available. Meaning if I jump to 13:21:11:03 on the video track, I can jump to the same place in the audio and instead of using 2 ropey audio tracks I can choose from 16 radio mics, boom mics and whatever else they might have plugged in.
This saves time because otherwise you have to line up the audio to the video by ear - easier if you shot using clapper boards but still pretty time consuming. I shot something a few months ago using a Roland recorder stuck on the top of my 5Diii. I experimented with an iphone app which produced TC audio through the iphone's speaker (I waved it in front of my boom mic and the canon's built in mic whenever i started recording). It was a bit rubbish and I got bored of doing it. The following week I spent a good day synching up my audio with my video before even starting my edit. Something else i noticed is the camera's internal clock wavers quite a bit throughout the day. I was recording audio in hour or two chunks but recording video in 1 to 5 minute chunks and the offset between the audio and video wavered by up to a 2 seconds over an hour.
So, this particular implementation of timecode would involve you plugging a line from the headphone jack of the camera into a spare channel of your audio recorder and enjoying painless editing.
Anyway - TC is really handy depending on what you're shooting.
