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Using timecode, LTC, SMPTE on a film set
Hi I’m getting into recording and editing audio for film and video, and I’m trying to understand about timecodes and SMPTE and LTC, etc. I have experience in the studio with music production. I also have live music/sound experience. I have a couple of questions that I was hoping to get some help with. I’ve tried doing some googling myself, but I can’t find any good introductory articles.
1) How do timecodes work on film, especially when syncing camera footage and audio when a separate audio recording unit is used? How does SMPTE and LTC work? I looked up some of this info on Wikipedia but the articles are fairly technical and not that helpful for someone who is new to the industry.
2) Where does the clapper fit in with respect to syncing audio and video? I always thought the clapper was used to sync the start of each take by lining up the clap sound on the audio file with the clap motion on the video file. Of course this manual process can be tedious when working with multiple cameras/angles and many scenes and takes. But if the clapper is used to manually sync audio and video, what’s the point of a timecode, and especially a timecode generator?
3) What should I look for when buying a recording unit for on-location recording? I understand this is better than using the camera’s built-in audio recorder as most non-pro cameras (DSLRs, digital camcorders, etc.) will have fairly poor built-in pre-amps. Should I consider buying a separate pre-amp in addition to a recording unit? Or will most pro units have a decent built-in pre-amp?
Thank you so much for any help you can give me.
David H. Watson
dEhiN Entertainment -
15 Replies
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HI. SMPTE is the name for a standard which includes LTC (Longitudinal timecode, CTRL(control track) , ViTC (vertical interval timecode. Userbitas are also definable.
Its use is much more on the video side of things rather than film. LTC is an audio signal but when it moves very slowly in editing, the signal becomes unreadable, so the VITC (embedded tc on top of picture remains valid). TC readers switch between LTC and VITC automatically. Timecode really comes into its own when hooked up to a timecode reader of some sort.
The clapper is a manual process by and large, although syncing softwares do exist to sync up sep sound and picturs, but they dont use tc i dont believe, but the audio signal.
Pluraleyes is one such utility.
Thje clapper has written on it the scene and take no amongst other things. The clap sound is a large short transient that allows the sound file to be accurately synched to the picture having 1st read the take no and scene data etc.Hope that helps.
Peter
Post Production Dubbing Mixer
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Time-code is a way of “stamping” a clock time to be used as a reference point in media data.
Normally “time of day” is used in 24hr mode, so ALL the recorders (camera/s, video + audio) have the same time-code at the same time during a shoot so shots can be retrieved at a later time.
LTC (longitudinal / linear TC) is now a thing of the past and suited to tape based shooting.
During a shoot all recorders are referenced to a master time clock [normally the main camera or TC slate], all the recorders then operate in ‘free run’ mode and every few hours [meal & coffee breaks] they are then jambed synced to maintain alignment or via a RF time code sender.
The DA or ‘script chick’ and use a standard digital wrist watch to then log the useable takes as this will be set to time of day which is also TC time.
In post all the required material audio / video is brought into an editing time line using the TC as an alignment tool, clapper boards etc are then used to perfectly align the various tracks.DSLR cameras do not have time-code so other methods are used to sync the audio to video.
I hope this basic overview helps with your question….
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[Peter Groom] “Its use is much more on the video side of things rather than film.”
Hi Peter, I assume you are referring to LTC/ViTC/CTRL? If so, then what is generally used in film to sync?
David H. Watson
dEhiN Entertainment -
Hi Brian thanks for your response. It does help but I have a few follow-up questions:
[Brian Reynolds] “During a shoot all recorders are referenced to a master time clock [normally the main camera or TC slate], all the recorders then operate in ‘free run’ mode and every few hours [meal & coffee breaks] they are then jambed synced to maintain alignment or via a RF time code sender.”
Is this the case with LTC? You mentioned LTC is now a thing of the past. In that case, does the above still apply today to whatever TC format is used?
[Brian Reynolds] “The DA or ‘script chick’ “
Sorry to sound like a newbie, but what does DA stand for? I’ve heard the term script chick, and I think it’s the person (traditionally a women I guess?) who makes sure the filming is going according to script. Is that the same as continuity supervisor?
Also nowadays how are things done? Do all recorders still operate in ‘free run’ mode or are they more tightly synced?
Where does SMPTE come in? If I understand Peter correctly, SMPTE is the overall standard while LTC/ViTC/CTRL are specific methods of implementing the standard?
David H. Watson
dEhiN Entertainment -
SMPTE = Society of Motion Picture and Television Engineers.
The organization that comes / came up with various standards for Film / TV
https://en.wikipedia.org/wiki/SMPTEDA= Directors Assistant… amazing people for keeping shoots on time and under control which leaves the Director to do the ‘creative’ things.
PA= Producers assistant more involved in the management / financial side of a production.
Continuity Supervisor= making sure people are standing, wearing, holding, facing and looking where they should.LTC= (longitudinal / linear TC) this is normally recorded on one of the audio tracks in a tape based studio, in an audio multi track recording it would be placed on the last track of the machine ie track 16 or 24 etc then you need to leave the adjacent track empty as a guard track as the TC audio could bleed through a bit to the adjacent track. Giving a 16 track studio 14 usable tracks or 22 usable in a 24 track studio.
ViTC= vertical interval time code puts the information in the video control pulses.
CNTRL= probably uses the ‘control track’ of the videotape some how to embed the information there.
Digital card / hard drive recording has changed a lot of things but the basic principle stays the same of ‘time stamping’ data.Free Run would need to be used unless you have a CONSTANT input of TC data, so even with RF systems they often operate as Free Run/ jamb mode which will use the constant feed until or if there is a dropout with the input signal then it will continue to free run.
For example… top of the range units from Ambient Recording….
https://www.ambient.de/en/products/ambient-recording/clockit-timecode.html
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Wow, thanks Brian!
David H. Watson
dEhiN Entertainment -
David why the interest on time code are you looking at using it in a production and do you have any specific set up questions or to just expand your knowledge base?
The difference between Knowledge and Wisdom is… Knowledge is the knowing of facts…. Wisdom is the sensible application of good quality knowledge…
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More to expand my knowledge base; as I think I mentioned I am coming from a music production background. I want to get into video/film production, and am learning as much of the ropes as I can. I have joined a volunteer film production group to achieve this. But since I have a good audio/music production background, the group is looking to me as the “expert” on sound. So in addition to expanding my knowledge base, I am trying to learn as much as I can about the specifics of sound/audio production for film, including things like on-set/location recording.
Specifically with time code, I was considering whether it’s worth it for the group to use a TC system for syncing or stick to manual using the clapper. I’m thinking the manual should work for now. The group primarily produces short films and uses 2 cameras at most. We recently purchased a separate portable recorder, but before the mic(s) were feeding directly into the camera being used, which ranged from pros like RED to DSLRs to HD camcorders. (The cinematographers on each production used whatever camera they owned).
David H. Watson
dEhiN Entertainment -
My suggestion is go a manual clapperboard system to start with.
I do TV,Film & Radio audio 6 days a week and the last time I did a full TC job was about 6 months ago with 8 cameras and 2x 16 track Mac PC based recorders for a kids hidden camera prank show.
The camera TC was set to 01:[then clock minutes] for camera 1, 02:[then clock minutes]for camera 2, 03:[then clock minutes]for camera 3 etc. This was done for later card / camera identification.
In post prod an ‘offset’ was then added to each file to suit as to time match the video from each camera…… BUT prior to that I hadn’t done a serious TC job for 10+ years.A lot of commercial jobs I do on a day by day basis are DSLR and SD or CF audio record (NON TC). Or direct to broadcast video camera with a backup record (that has never been needed also NON TC).
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Hello David and welcome to the Cow Audio Forum.
You’ve been given some really good advice here.
One point in your last post. Seldom do mics get plugged directly into cameras in professional work.
Mics go to a mixer and then to camera. Mixers are more than knobs that let you vary the volume.
1. They let you vary volumes without shaking the camera or getting in the way of the camera op.
2. You may need to do that a lot with some people. I ride gain even if one person is talking if their voice fades on the end of each line. You can only do this in a relatively quiet environment, otherwise you bring up the ambient noise.
3. Mixer preamps (good ones) sound better than camera preamps.
4. Good mixers have input transformers that scrape off RF before it get into your audio.
5. Good mixers have limiters that allow you to record hotter, keeping your audio further above the noise floor without distorting.
6. Good mixers have EQ that lets you roll of LF HVAC noise before it gets into your audio.
7. Good mixers have mulitple outputs so you can feed more than one camera, or separate recorder simultaneously.
8. Good mixers make your sound better. If they didn’t pros wouldn’t use them.Regards,
Ty Ford
Cow Audio Forum Leader
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