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# Timecode sample description

An atom that defines how to interpret time code media data.

## Overview

The timecode sample description contains information that defines how to interpret time code media data. This sample description is based on the standard sample description header, as described in [`Sample description atom`](/documentation/quicktime-file-format/Sample_description_atom).

The data format field in the sample description is always set to `'tmcd'`.

The timecode media handler also adds some of its own fields to the sample description.

## Topics

### Data fields

[`Reserved`](/documentation/quicktime-file-format/Timecode_sample_description/Reserved)

A 32-bit integer that is reserved for future use.

[`Flags`](/documentation/quicktime-file-format/Timecode_sample_description/Flags)

A 32-bit integer containing flags that identify some timecode characteristics.

[`Time scale`](/documentation/quicktime-file-format/Timecode_sample_description/Time_scale)

A 32-bit integer that specifies the time scale for interpreting the frame duration field.

[`Frame duration`](/documentation/quicktime-file-format/Timecode_sample_description/Frame_duration)

A 32-bit integer that indicates how long each frame lasts in real time.

[`Number of frames`](/documentation/quicktime-file-format/Timecode_sample_description/Number_of_frames)

An 8-bit integer that contains the number of frames per second for the timecode format.

[`Reserved`](/documentation/quicktime-file-format/Timecode_sample_description/Reserved2)

An 8-bit quantity.

[`Source reference`](/documentation/quicktime-file-format/Timecode_sample_description/Source_reference)

A user data atom containing information about the source tape.


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