TC from Audio track into Linear TC

[Matt McGowin]

I was wondering how time-code on an audio track is translated into linear time-code.

Any help is appreciated

Matt

[Jeff Wexler]

Timecode as audio on a track IS linear timecode. The "audio" that is smpte timecode plays out as linear audio just like other audio plays out linear. The linear output of the TC audio track has to be read (not listened too) by a TC reader.

[Actualsizeaudio]

This product will stamp QT movies with audio track TC: http://www.videotoolshed.com/product/26/fcp-auxtc-reader

Or if you are looking to for an external box for reading linear TC, there are a bunch, including Digidesign's sync I/O, or a cheap box that works great that I have a few of, the MOTU Digital Timepiece. There are many others, but the boxes I mention generate a clock signal from LTC so you can actually lock another device to the TC printed on the audio track (or coming off the TC track of a tape, or out of the TC out spigot of a recorder, etc).

Basically, timecode on an audio track IS linear TC. For these sync boxes to work you just need to make sure your levels are correctly set.

[cmgoodin]

Thank you for the reply.

How is the time-code on the audio channel read by a TC reader?

Can ProTools 9 read the TC without additional hardware?

LTC (Longitudinal Time Code) on an audio channel is not normally a standard used for sync.  Most Time Code outputs of Digital recorders and Digital cameras is derived from a Metadata stamp and the sample clock of the recording device.

LTC is a hold-over from analog days where it was recorded on a control track of some Tape based audio and Video recorders. It can be used in a facility to synchronize real-time playback of multiple tape machines to a master time signal (Chase lock).  It was also used on audio cassettes given to transcription so a time coded transcription could be generated.  Time Code Readers that read LTC code take the audio signal and  run it through a Schmidt trigger or other type of signal level discriminator and the timing between 0 crossing points of the pulses is measured against the clock rate established in the sync word.  The code itself is a Pulse width modulated 80 bit string of  BCD numbers that are decoded by a micro-controller or microprocessor and output as a ASCII text string or sent as BCD data to a Seven segment display controller to display the time as HH:MM:SS:FF.  Hours minutes seconds and Frames.    For more comprehensive info look up SMPTE Time code or Longitudinal Time code on Wikipedia.

Don't know if Pro Tools 9 decodes LTC on an audio track .    It never did before version 9 without some kind of 3rd party plug in.  Boom Recorder and Gallery's Metacorder can use LTC on an audio input channel to stamp their BWF files.  But I don't believe they  use that code when playing back. They calculate TC based on the time stamp in the header and the sample clock of the file.  As mentioned in another thread on this forum Ambient makes a free app for IOS deivces iPad, iPod, iPhone available for download on the iTunes Store that will decode and display LTC presented to the microphone input of the device.  You do need a special padded cable since most LTC is line level.

----Courtney

[Matthias Richter]

Avid can read the Audio-TC by a function called special - read audiotimecode

FCP needs additional software e.g.AuxTC Reader from videotoolshed

[Andy P]

I don't know about the FCP Aux TC software, but for the Avid procedure it takes some time to convert the audio TC to data. A 40 min tape took 35 min to process, so this may be an issue in the edit if they are deciding which method to use. As stated by others previously,I would say if you're shooting with a 5D, recording a guide mix is more useful than LTC, then use Plural Eyes to sync.

[Actualsizeaudio]

The auxTC software does it in a batch process. It takes but 10 minutes at the most for a days worth of shooting. It is very streamlined, and very forgiving.

Pro Tools 9 can not decode audio TC as far as I know. You need either a Sync I/O, or another box that converts the LTC to MTC (midi time code). These boxes are not expensive, and there a bunch of them.

I've never heard of a plug-in that can analyze a digitized audio file and read it as LTC. Maybe there is such a thing but I've never heard of it.  I once had installed on my machine a really cheap app that turned LTC coming in on the mac's audio input into TC. I just googled looking for it and I can't find it, or rememebr what it was called.........grrrr

[Actualsizeaudio]

I found it!: http://nobusiness-soft.com/smptereader/

Also, it should be mentioned, the AuxTC app way is much quicker to use then Plural Eyes, but requires $250 to leave your pocket, as opposed to the $150 for Plural Eyes.

[Yatess]

Thoughts on this workflow. H4n, 2 iRig Pres, TC Buddy, adaptor cable to connect output of iRig Pres to H4n Ch1&2 (1/8" TRS), iDevice with Movie Slate App. Ch1 will have boom mic, Ch2 will record TC from TC Buddy. Ch 3&4 (rear XLRs) will have two lavs. iDevice, receiving TC via WIFI, wiil be attached to manual slate converting it to a smart slate. This all works well in theory and on the bench. I haven't worked in post with content using this method though. I use FCPX. Any thoughts on post workflow? I use a SD 744t and 552 mixer normally but I'll be traveling overseas and want to travel light as well not put my main audio kit at risk.

Scott

[studiomprd]

" Any thoughts on post workflow? "

TEST IT

do a workflow test.

[Marc Wielage]

iDevice, receiving TC via WIFI, wiil be attached to manual slate converting it to a smart slate. This all works well in theory and on the bench. 

 

I'm not happy with the viewable TC numbers of iPhones or iPads in bright sunlight or bright set lights; they can work fine in moderate room lighting. I think a traditional Denecke or Ambient slate is far more reliable. If you're cramped for space, get a Denecke TS-C. 

 

Note there's always the potential for WiFi interference and/or dropouts, though TC Buddy should keep chugging along if it encounters a data packet loss. 

 

I've always been vexed by ideas that work well on the bench, then when I get in the actual situation, I encounter challenges I never could have imagined -- like idiots who drop stuff, batteries that fail early, snarled cables, etc.  

[chris_bollard]

Just finished a network pilot that was 2/3 shot on 5D, two cameras natch.

We were filming in a small family home so I had to strip my kit down to fit a 601 so I didn't block doorways and the hallway so my Tc slate wasn't first option.

After some tests and chat with post I went with a idevice Tc display, bit fiddly but worked; I suggested plural eyes and they got that and were ultimately happy to run with that (still shooting visual Tc too when possible)

LTC does work but needs to be tested and record levels set