[HH:MM:SS:FF]

[HH:MM:SS:FF] : Shorthand format for timecode data; HH = hours (2 digits), MM = minutes, SS = seconds, FF = frames. So, a timecode that is displayed as [01:22:34:29] is 1 hour, 22 minutes, 34 seconds, and 29 frames.

Active Picture Area: The portion of the video frame that is displayed on the video monitor that actually has a picture on it.

Application: In this case, the software resident on the PC that communicates directly with the V8 API. This would include a hardware support layer.

AUX port: Transport control port accessory for the Timing Gear^®. Used to control the transport on parallel-wired decks (such as the Tascam DA-30 MkII DAT recorder).

Bi-phase mark code: Formerly known as Manchester coding, this is a self-clocking, phase-insensitive modulation method where a transition always takes place at a clock edge, and an additional transition between the edges marks a logical 1. It is the Nyquist limit of frequency-shift keying. Used as the modulation method for LTC.

Burn-in window: Rectangular window overlay on the video output which displays timecode.

Chase lock: Allows the Timing Gear^® to follow an external timecode input so that the audio in the project will follow that timecode.

Contiguous: Tied together with common boundaries. In our case, it is used to categorize a series of timecode frames that are continuously incrementing or decrementing by a preset amount (normally 1 frame). For example, the series of numbers [1, 2, 3, 4, 5 , 6, 7] is contiguous, where [1, 2, 3, 4, 6, 7, 8] is not (due to the missing ‘5’). Note that this should not be confused with continuous timecode, which deals with the presence or absence of the signal, not the data.

Continuous: In our case, this describes whether a timecode signal is present at all times. For example, most professional VTRs have an LTC output that remains continuous even when the tape is stopped, but a cheaper VCR that simply has LTC recorded on one audio channel will cease sending timecode when the tape is stopped; this would be discontinuous. Careful here not to confuse this with a discontinuity: whether timecode is continuous does not depend on the data, but whether the signal exists. Ugly, I know.

Direction: LTC can be read in either a forward or backward direction. For instance if LTC is striped to a tape, then that tape is reversed and played backwards, the LTC direction would be reverse. This should not be confused with whether the data is incrementing or decrementing, though usually they are the same.

Discontinuity: Break in the expected sequence of timecode data. During normal operation, timecode increments by one frame. If the increment value is suddenly different from the expected value, it is said to be discontinuous. There are two types of discontinuities: a bound event (such as the sequence [1, 2, 3, 4, 5, 99, 7, 8, 9]), or unbound (such as the sequence [1, 2, 3, 4, 36, 37, 38, 39, 40]).

Drop frame: Used to make up the difference between format and framerate in timecode where they are dissimilar. For instance, with 29.97 drop-frame timecode, a total of 108 frames are ‘skipped’ or dropped every hour during the count; this makes up for the tenth-of-a-percent slowdown from 30 fps. You will learn to hate drop-frame before you’re done.

Dropout: Temporary loss of signal or data: a dropout is fairly common in tape-based systems. Also defined as the latter third of "tune in, turn on, …".

Event: A single frame of timecode data described in [HH:MM:SS:FF] format. Used to signal the passing of a specific timecode data frame.

Format: The number of frames per timecode second: this indicates how many frames make up one second of SMPTE time, much in the same way that 60 seconds make up one minute. This number does not change with the speed of the device, and is always an integral number. For instance with 29.97 drop-frame timecode, the timecode framerate is 29.97 frames/sec, while the format is 30 frames/sec, drop frame.

Formatting: The act of preparing a data storage device for writing data. In the case of audio or videotape, it usually means laying down a sync signal along the entire length of the tape to be used.

Frame: The smallest unit of SMPTE timecode; originally taken from the representation of one exposed frame of motion picture data.

Framerate: The number of frames per second of real time: this indicates how many physical frames pass by a given point in one real second, and it depends on the speed of the device generating the timecode. As the device speeds up or slows down, the framerate can change. This number can be fractional.

Framesync: Synchronization "heartbeat": provides the reference for all of the frame-based timing functions of the Timing Gear^®, including LTC output and reading of timecode data from multiple sources.

Freewheel: Replaces the data lost during a dropout with the data that is expected to be there. For instance, the sequence [1, 2, 3, ., ., ., 6, 7, 8, 9] is missing some data; freewheel would replace this data with [1, 2, 3, 4, 5, 6, 7, 8, 9]. Usually a limit is placed on how many frames will be replaced before determining that a serious error has taken place.

Genlock: Generation lock: generates a system clock locked to an external source such as a video signal or word clock. In synchronization terms, makes sure that everything is running at the same rate. See Resolving.

GPI: General Purpose Interface: accessory for the Timing Gear^®, which allows external contact-closure events to be recognized and generated by the Timing Gear^® card. Up to 8 separate inputs and outputs are available simultaneously.

House Sync: Master sync source used to tie several pieces of equipment together. Commonly a video signal that would run throughout an entire facility; could also be a master word clock signal, or in more esoteric situations, a GPS data signal.

Idle: State of timecode where the positional information is staying the same from frame to frame. Indicates that the device generating the timecode is parked in one position, or locked on one frame.

Jam sync: Used to match a timecode generator to a timecode source at a single point. The data from the timecode source is "jammed" into the timecode generator, and the generator starts from that point.

LTC: Longitudinal Time Code (AKA Linear Time Code): Timecode that is written as a series of 80 bits using a modulation scheme known as bi-phase mark encoding. The LTC specification has been ratified by SMPTE, and has been in use for many decades.

MIDI: Musical Instrument Digital Interface: a standardized method of sending data from one device to another via a current-loop optically isolated system. Originally designed for connecting synthesizers together, it has been expanded to provide timecode and machine control functions.

MTC: MIDI Time Code: a specific method of sending timecode positional information via a MIDI port.

NTSC: National Television Systems Committee: the body behind the American color television standard. Sometimes referred to as ‘Never The Same Color’. Ingenious but arcane method of piggybacking color information on the old monochrome video signal, which resulted in the reduction of framerate from 30 fps to 29.97 fps, and the resultant drop-frame timecode.

Offset: Amount that is added to the output of the Timing Gear^®; can be used to alter the timecode output to match an existing project.

PAL: Phase Alternating Line; the colour television system used in most of Europe. 25 frames/sec. No drop frame calculations. Better color.

Pullup/Pulldown: When a motion picture film is transferred to NTSC video, a method called ‘3:2 pulldown’ is used to convert the 24 frames/sec of film to 30 frames/sec of video. Unfortunately, NTSC video runs slightly slower, at 29.97 frames/sec, so to do the transfer, the film projector is slowed down to 23.976 frames/sec to compensate. This slowdown affects the audio that is associated with the film, so audio that was originally shot at 44.1kHz is pulled down to 44.056 kHz to compensate. Alternatively, if the sound originated from the video edit, when it is transferred back to film, it has to be pulled up to 44.144kHz to compensate.

Redundant: See redundant.

Resolving: Using a clock as a reference signal to generate a master clock based on that signal; for instance, using a video black-burst signal to generate a digital audio word clock. See Genlock.

Samplerate: The rate at which audio samples are taken: usually 44.1 kHz or 48 kHz.

SMPTE: Society of Motion Picture and Television Engineers: The governing body behind the standards used in the motion picture and television industries. Sometimes used interchangeably with LTC.

Stable: State of timecode where the positional information data is either changing in the same way, or has been idle for some period of time. Indicates that the device producing the timecode has either reached running speed, or has come to a full stop.

Status: In this case, the status is the state of the timecode data.

Stripe: Striping a tape means laying down a contiguous stream of timecode onto a tape so that it can be used for a reference later on. It is important that the timecode data being laid down is contiguous and does not have any duplicate frames, and if it is to be synchronized with a framesync source, that that source is used to key the generation of the timecode.

TBC: Time Base Corrector: used in video, a device that (digitally) stores a frame of video data and re-clocks it out referenced to a stable timebase, such as a crystal. It is used to eliminate timing jitter that comes from videotape, and is usually included in expensive professional VTRs.

Timecode: A method of providing a specific and unique label to a location in a project. Although it is intended primarily for visually based projects such as motion-picture film or videotape which have very clear delineations of frames, it can be used to provide positional information on linear (tape-based) media as well.

Timing Gear^®: Brand-name synchronization device from Digital Audio Labs. Allows chase lock to SMPTE timecode, as well as resolve to video, house sync, and other sources.

Trauma: As in blunt-force trauma: a medical term describing the results of injury due to banging your head against a wall without protection.

Unstable: State of timecode where the data is in a transitional phase between idle and running. Indicates that the device generating the timecode is changing in speed, either speeding up or slowing down.

Vertical Interval: For our purposes, the area of the video frame outside of the active picture area of the video frame. This is the "black bar" area at the top of the video image, usually just off-screen, and consists of the first twenty lines of video from the top of the image. These lines are usually blank, but can be used to carry information like VITC, closed-caption data, teletext, and the like.

VITC: Vertical Interval Time Code: Timecode that is written in the vertical interval of the video frame. It is written as 90 bits, which allows for some error correction. VITC is written along one line of the video field, with a second duplicate line being written for redundancy.

VTR: Video Tape Recorder: Professional level videotape recorder. Usually comes with features not found on less-expensive consumer-level machines such as a TBC, remote transport control, genlock, and insert editing features.

Word Clock: TTL-level clock used to drive the sample clock and associated systems. Word clock is generally held to be the same as the samplerate; for instance, with a 44.1 kHz samplerate, the word clock is a square wave with a period of 22.676 m s (44.1kHz). Termination of word clock is typically 75 W .