Last Updated 5 hours ago
Filmmaking Dictionary: Number 2 / 2-Pop (Sync Mark)
Definition
A 2-pop is a brief synchronization reference placed two seconds before the agreed start of programme picture. It commonly pairs a one-frame visual mark with a one-frame audio tone, often at 1 kHz, so picture and sound can be aligned during post-production.
The name refers to its position before the start, not to a tone lasting two seconds. The mark belongs in the leader or turnover material specified by the workflow; it is not normally part of the audience-facing programme.
Where It Goes
In a straightforward 24 fps example, if first picture begins at 01:00:00:00, the pop is placed at 00:59:58:00. It sits 48 frames before first picture. Use the project’s agreed frame rate, timecode convention and leader template rather than moving the mark by eye.
The visual mark and the audio event must refer to the same frame boundary. If an export shifts the audio or picture, comparing those events gives the receiving team a clear reference for the offset.
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Why Sound Post Uses It
A sound editor may receive a reference movie and separate audio files or an edit interchange file. A matching pop helps establish whether those elements share the same start alignment. It is especially useful when different applications interpret file start times or leader lengths differently.
A head pop cannot prove that the whole programme remains synchronized. A file can start correctly and drift later because of an incorrect frame-rate or sample-rate interpretation. A tail reference, dialogue checks and the delivery team’s normal quality control address those additional problems.
Turnover Checks
- Confirm the first-picture timecode and the project’s exact frame rate.
- Check that picture and audio reference events line up on the intended frame.
- Use the tone level and leader format requested by the sound team.
- Keep all exported versions consistent with the same approved reference.
- Remove or retain leader according to the final delivery requirements.
Common Mistakes
- Making the tone two seconds long.
- Assuming a 2-pop is the same as a sustained line-up tone.
- Moving first picture while leaving the pop at its old position.
- Using a correct head pop as proof that no sync drift exists.
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Frequently Asked Questions
Is the pop a loudness calibration signal?
Its main purpose is synchronization. Sustained reference tone and programme loudness measurements serve different purposes.
Should every exported video include one?
No. Use the version and leader required by the receiving department or delivery specification.
Related Terms
Browse all terms starting with 2 or return to the filmmaking dictionary.