Used in

television production A television show – or simply TV show – is any content produced for viewing on a television set which can be broadcast via over-the-air, satellite, or cable, excluding breaking news, advertisements, or trailers that are typically placed be ...

and

filmmaking Filmmaking (film production) is the process by which a motion picture is produced. Filmmaking involves a number of complex and discrete stages, starting with an initial story, idea, or commission. It then continues through screenwriting, cast ...

post-production Post-production is part of the process of filmmaking, video production, audio production, and photography. Post-production includes all stages of production occurring after principal photography or recording individual program segments. Th ...

, a 2-pop is a 1 kHz tone that is one frame long and placed 2 seconds before the start of a program. It is a simple and effective method of ensuring

synchronization Synchronization is the coordination of events to operate a system in unison. For example, the conductor of an orchestra keeps the orchestra synchronized or ''in time''. Systems that operate with all parts in synchrony are said to be synchronou ...

between sound and picture in a video or film. A 2-pop is typically placed at the end of a visual

countdown A countdown is a sequence of backward counting to indicate the time remaining before an event is scheduled to occur. NASA commonly employs the terms "L-minus" and "T-minus" during the preparation for and anticipation of a rocket launch, and ev ...

. Only the first frame of the "2" is shown, and the remainder of the 2 seconds prior to the program is black. This provides a unique point of reference where the frame-long image and frame-long sound should align, similar to the way a film

clapperboard A clapperboard (also known by various other names including dumb slate) is a device used in filmmaking and video production to assist in synchronizing of picture and sound, and to designate and mark the various scenes and takes as they are ...

is used to generate a synchronization point. For example, in a television or video program the first frame of action (FFOA) starts at one hour (typically timecode of 01:00:00:00 in the US, and 10:00:00:00 in the UK), preceding that, 1 frame (or the 2-pop) of tone would be placed at timecode 00:59:58:00 or exactly 2 seconds before first picture. Alternately, in film post-production the leader starts at 01:00:00:00 (or 0+00 feet if using feet and frames as is common in the United States), the 2-pop starts at 01:00:06:00 (or 9+00), and the first frame of action (FFOA) starts at 01:00:08:00 (or 12+00). A 2-pop is useful whenever picture and sound are handled separately. For example, projecting work-in-progress in the pre-video days involved a

film projector A movie projector is an opto-mechanical device for displaying motion picture film by projecting it onto a screen. Most of the optical and mechanical elements, except for the illumination and sound devices, are present in movie cameras. Modern ...

linked to a magnetic

dubber Dubber is a cloud based call recording software which operates as a software-as-service (SaaS) and voice data offering. Dubber was founded in Melbourne, Australia in 2011 by James Slaney, Steve McGovern and Adrian Di Pietrantonio, and predominan ...

, onto which the separate soundtrack reel was loaded. Aligning them by the 2-pop would ensure proper synchronization during playback. A modern scenario would involve sending a soundtrack to a separate facility for a sound mix. The returned product is a computer audio file, which then needs to be synchronized again with the picture.

Sample sound

Whereas laying down

bars and tone SMPTE color bars are a television test pattern used where the NTSC video standard is utilized, including countries in North America. The Society of Motion Picture and Television Engineers (SMPTE) refers to the pattern as Engineering Guideline ( ...

prior to program start establishes video and audio

calibration In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of kno ...

levels on the tape, the 2-pop is primarily used for picture and sound

. Therefore, while the

loudness In acoustics, loudness is the subjective perception of sound pressure. More formally, it is defined as, "That attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud". The relation of ph ...

of the 2-pop may be the same as the

audio level in use, this is not a requirement. The loudness level should be sufficient to be heard clearly.

References

External links

What is 2-Pop & How is it used?
Henri Rapp Recording Television terminology Film and video technology {{film-tech-stub