SMPTE timecode is a set of cooperating standards to label individual frames of video or film with a timecode defined by the Society of Motion Picture and Television Engineers in the SMPTE 12M specification.

Timecodes are added to film, video or audio material, and have also been adapted to synchronize music. They provide a time reference for editing, synchronisation and identification. Timecode is a form of media metadata. The invention of timecode made modern videotape editing possible, and led eventually to the creation of non-linear editing system

Basic concepts

SMPTE timecode signal compared to the outwardly-similar manchester code.

SMPTE timecodes contains binary coded decimal hour:minute:second:frame identification and 32 bits for use by users. There are also drop-frame and colour framing flags and three extra 'binary group flag' bits used for defining the use of the user bits. The formats of other forms SMPTE timecodes are derived from that of the longitudinal timecode.

Time code can have any of a number of frame rates: common ones are

• 24 frame/s (film)
• 25 frame/s (PAL colour television)
• 29.97 (30/1.001) frame/s (NTSC color television)
• 30 frame/s (American black-and-white television) (almost obsolete)

In general, SMPTE timecode frame rate information is implicit, known from the rate of arrival of the timecode from the medium, or other metadata encoded in the medium. The interpretation of several bits, including the "colour framing" and "drop frame" bits, depends on the underlying data rate. In particular, the drop frame bit is only valid for a nominal frame rate of 30 frame/s: see below for details.

More complex timecodes such as Vertical interval timecode can also include extra information in a variety of encodings.

Contact Information

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Electronic mail 
     mmorel@avidproductions.com

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