Burnt-in timecode

Burnt-in timecode (BITC), also called burned-in timecode, visual timecode, or window burn, is a human-readable timecode display that is permanently superimposed over the picture area of a video or film image. It usually appears as a numeric string in hours, minutes, seconds, and frames, and is described as “burnt in” because the text becomes part of the visible image pixels rather than remaining separate metadata. Burnt-in timecode is widely used in film, television, and video production for dailies, review copies, logging, quality control, legal reference, and other situations in which a person must be able to identify a specific frame or clip without specialized timecode-reading equipment.

Definition and overview

In professional media workflows, timecode is a system for assigning a unique address to each frame of a moving-image recording. Timecode is usually stored invisibly as metadata: it may be recorded in the vertical blanking interval of a video signal, on a linear audio track, in the data tracks of a digital file, or in a file header. Burnt-in timecode is different in that it is a visible representation of that metadata, rendered into the image itself. Once the timecode has been overwritten onto the picture, it cannot be switched off or removed cleanly without cropping, masking, or otherwise altering the image.

A burnt-in timecode window commonly shows a string such as 01:12:34:15, indicating one hour, twelve minutes, thirty-four seconds, and fifteen frames. The display may also include additional information such as the date, reel number, clip name, source or record timecode, keycode, audio timecode, or camera identifier. The overlay is produced by a timecode inserter, character generator, nonlinear editing system, or transcoding tool during playback, duplication, recording, or file export.

Technical characteristics

Display format

Burnt-in timecode is most often based on SMPTE timecode or EBU timecode. The normal display format is HH:MM:SS:FF, where HH is hours, MM is minutes, SS is seconds, and FF is the frame count within the current second. In drop-frame timecode, used with NTSC frame rates such as 29.97 fps, the separator between seconds and frames is frequently shown as a semicolon rather than a colon—for example, 01:00:00;02—to signal that frame numbers are skipped in a regular pattern. In non-drop-frame timecode, all separators are ordinarily colons.

The frame portion of the display depends on the selected timecode rate. Common rates include 24, 25, 29.97 drop-frame, 29.97 non-drop-frame, and 30 frames per second. In some high-frame-rate workflows, the timecode may count frames at 50, 59.94, or 60 fps, but the visible format generally remains a two-digit frame value within the relevant counting system.

Position, size, and legibility

Burnt-in timecode is usually placed in the lower third or upper area of the frame, often inside the safe-action or safe-title area so that it remains visible on consumer displays. It is commonly rendered in white, yellow, or green characters with a black or semi-transparent background box to maintain legibility over bright and dark picture content. The size and opacity of the burn-in can often be adjusted, but the most reliable practice is to make the digits large enough to survive compression and re-encoding.

Source of the timecode

The timecode that is burnt into an image may come from several possible sources. In traditional tape-based workflows, a timecode reading device could decode linear timecode or vertical interval timecode and feed it to a character generator. In file-based workflows, software reads an embedded timecode track or a sidecar file and composites the desired text during export or playback. The burnt-in value may be the source timecode of the original camera file, the record timecode of a tape, or a timeline timecode from an edit sequence. It is therefore important to label which type of timecode is being displayed, because source, record, and sequence timecode can differ.

Purpose and uses

Dailies and rushes

One of the most common uses of burnt-in timecode is in the production of dailies or rushes. During film and television production, camera footage is transferred or transcoded into review copies that editors, directors, producers, and crew members can watch. These copies often include visible timecode along with other information such as keycode, roll number, scene, take, and camera index. Because the timecode is part of the picture, anyone watching the daily can note an exact frame reference that remains meaningful as the footage moves through offline editing, conforming, and finishing.

Review, approval, and collaboration

In post-production, burnt-in timecode is often applied to review copies for directors, producers, visual-effects artists, colourists, and clients. A reviewer can refer to a precise moment by reading the visible timecode, even if the file is played on a laptop, tablet, or web-based review platform. This reduces ambiguity in comments and change requests. Such copies are sometimes called “dirty” copies because they contain visible overlays, as opposed to “clean” copies that carry no burnt-in text.

Offline editing and proxy workflows

In proxy-based post-production, low-resolution files may be generated for editing while the original high-resolution material is kept offline. Burning timecode into the proxy files allows editors and assistants to verify that the correct source clip is being referenced. The visible timecode can also help with logging, transcriptions, subtitling, and conforming, although automatic conform processes normally rely on the underlying timecode metadata rather than on the visible image.

Broadcast quality control and logging

Broadcasters and post facilities may use burnt-in timecode in quality-control copies, compliance review copies, or logging masters. The visible timecode allows an operator to record exactly when an issue occurs—such as a glitch, missing caption, or audio problem—without needing to open the file in a specialist player. In some cases, multiple rows of burn-in data are displayed, showing timecode, time-of-day, duration, and asset identifiers.

Legal and forensic applications

Burnt-in timecode is also used in forensic video analysis and legal evidence. Copies of surveillance video or other recordings may be produced with visible timecode so that analysts, attorneys, or courts can refer to particular frames. However, burnt-in timecode by itself does not prove that a video is authentic or unaltered. It is a visible label generated from the available timecode source, and it may be incorrect if the source timecode was reset, offset, or otherwise inaccurate.

Archival and access copies

When older tape or film material is digitized, archives sometimes create access copies with burnt-in timecode as a preservation aid. If the original timecode metadata is later lost or cannot be read, the visible timecode still provides a frame reference for researchers. This is a trade-off, because the burn-in remains permanently in the access copy and may obscure part of the original image.

Burnt-in timecode and timecode metadata

Burnt-in timecode should not be confused with timecode that is stored as data. Ancillary timecode, linear timecode, vertical interval timecode, and file-based timecode are all invisible to the viewer and require compatible hardware or software to decode. They can be present, removed, or replaced without altering the visible picture. By contrast, burnt-in timecode is self-contained: it can be read from any video monitor or image frame, but it cannot be removed without damaging the image.

The two forms usually complement each other. In a professional workflow, machine operations such as conforming, synchronizing, and frame-accurate capture use the underlying timecode metadata, while human reviewers use the burnt-in display. If the metadata and the visible timecode movement disagree, the cause is often a problem in the burn-in process, an offset in the timecode source, or a frame-rate conversion error. For this reason, burnt-in timecode should be used as a visual guide rather than as the sole reference for frame-accurate technical operations.

Workflow and creation

Burnt-in timecode can be created in several ways. In traditional videotape and film-transfer workflows, a dedicated timecode inserter read linear timecode or vertical interval timecode and passed the video through a character generator before output. When film dailies were made on tape, the telecine or film scanner often produced a window burn that combined timecode, keycode, and other camera or telecine information.

In modern file-based workflows, nonlinear editing systems and media transcoding tools commonly include a “timecode burn-in,” “window burn,” or “data burn-in” effect. The user selects the type and source of timecode, the position and size of the overlay, the background style, and whether additional metadata should be included. The burn-in is then applied during export, creating a self-contained review file. Some command-line transcoders can also generate such files automatically for large batches of material.

Because burnt-in timecode is created during output, it need not be present in the source recording. A clean master can remain clean while a separate review copy with burnt-in timecode is produced from the same source. This allows a facility to deliver both a clean program and a reference copy without duplicating the timecode burden in the master file.

Limitations and cautionary considerations

The main limitation of burnt-in timecode is its permanence. Since the text is part of the image, it cannot be removed cleanly. It may cover important picture information, interfere with lower-third graphics, subtitles, or captions, and make a copy unsuitable for final broadcast or distribution. It is therefore normally used only for review, dailies, logging, or forensic reference copies.

Burnt-in timecode can also become unreadable after significant recompression or when the image is scaled down. Aspect-ratio conversions, cropping, letterboxing, pillarboxing, and pan-and-scan operations can remove or partially obscure the burn-in window. If a code is placed too close to the edge of the frame, it may be cut off when the file is played on a display that overscans.

Another common problem is confusion between different timecode sources. A file may contain both source timecode and record timecode, and an edit sequence may have its own timeline timecode. If the burn-in window is not clearly labelled, or if the wrong source is selected, the visible numbers may be misleading. Similarly, drop-frame and non-drop-frame timecode must be identified correctly, especially in NTSC-based productions, because small frame-count differences can accumulate over long durations.

Finally, burnt-in timecode should not be treated as a security or authentication measure. It can be copied, cropped, retyped, or recreated just like any other visible part of an image. Its value lies in making a frame reference understandable to a human viewer, not in proving provenance.

Related terms

• Window burn / window dub: a copy of a video or film image with visible text overlays, often including timecode, keycode, and other metadata.
• BITC: common acronym for burnt-in timecode or burned-in timecode.
• Burn-in: the process of permanently compositing text, logos, or data into a video image.
• Clean copy / dirty copy: clean copy refers to a version without visible overlays; dirty copy refers to a version with burnt-in timecode or other burn-ins.
• Keykode: a machine-readable edge code on film that is sometimes displayed alongside timecode in film dailies.
• Source timecode / record timecode: different timecode references that may be carried in the same material and may be selected for burn-in display.

See also

• Timecode
• SMPTE timecode
• Linear timecode
• Vertical interval timecode
• Dailies
• Window burn