# MOV/MP4

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These preferences define the default export behaviors for **MOV**, **MP4**, and **MOV Reference** file formats. All options can be overridden per export job.

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**MOV / MP4 Options**

* **Fast Start (BETA)**\
  When enabled, the video/audio index (moov atom) is written at the beginning of the file for faster streaming performance.

  > Applies to both MOV and MP4 exports.
* **Use Resolve 709 (Display) Tag - W**When disabled, the color space in the MOV/MP4 file is set to 1,1,1 to indicate Rec. 709 (for either 709 (Scene) or 709 (Display)). When enabled, the color space is set to 1,2,1 (with “2” indicating an unknown transfer function), and a ‘gama’ atom with a value of 2.4 is added.
* **Use V2 Audio Description (MOV Only)**\
  When enabled, exports will use the **V2 Audio Description** atom. If unchecked, the older **V1 format** will be used.

  > Improves compatibility with newer software workflows.
* **Use Avid DNxHR Legacy Atom (MOV Only)**\
  When enabled, exports using **DNxHR** will use the older **Avid DNxHR Atom Description** for compatibility with legacy systems.

  > When unchecked, the newer format is used.

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**MOV Reference Options**

* **Check Video Frame Size**\
  Validates the frame size for every frame when creating **MOV Reference Files**.

  > Especially useful when referencing MXF files with padded frames.
* **Use URL Instead of Alis**\
  Enables the use of **modern URL-based referencing** rather than the legacy **Alis resource fork format**.

  > Alis remains more widely compatible, but URL is more future-proof.