Exporting OMF Audio Files

Open Media Framework—or OMF—is a cross-platform file format for exchanging video and audio sequence information between different editing systems. Avid originally developed the OMF file format, and many editing applications have incorporated some level of OMF import and export compatibility. Today, OMF is most often used for transferring audio sequence, track, and clip information from video editing systems to audio post-production applications. OMF can store far more information than traditional EDLs, especially when it comes to audio interchange.

When you export your sequence audio as an OMF file, the resulting OMF file contains a description of your audio edits (the clip In and Out points in the Timeline) along with the audio media files. You can use the OMF Export command if you plan to deliver your audio to an editor using an OMF-compatible digital audio workstation (DAW). Most audio facilities are able to use OMF files.

Using OMF for audio export has several important advantages:

Using OMF files, editors can send edited and synchronized audio tracks to an audio post-production facility, maintaining the original tracks, clip In and Out points, levels, pan, and cross fades. Audio handles can be added so that the audio editor can still trim and add cross fades to the audio as necessary.

Note: When you import OMF files into another application, make sure the sample rate in the application matches the sample rate of your OMF file. If the sample rates don’t match, your audio may be out of sync after it’s imported.

Limitations of OMF Exporting in Final Cut Pro

Before you export an OMF file, consider the following limitations:

  • If you have cross fades in your edit, they are exported as linear cross fades, regardless of what kind of cross fades you use in your edited sequence. Your audio editor can reset these to the correct type within the audio software.

    How well your cross fades import into another application depends on the tool your audio editor uses. Because some OMF importing tools do not handle cross fade objects correctly, you have the option to leave these out when exporting your sequence as an OMF file.

  • OMF export does not include disabled audio tracks (tracks with the Track Visibility control turned off). Any individually disabled audio clips are also ignored.

  • Speed and reverse-speed effects that have been applied to audio clips are permanently applied to the exported audio media files.

  • Nested sequences are mixed together and exported as a single audio media file.

  • Audio filter information cannot be exported in OMF files.

Make sure to test your audio workflow in advance. Not all applications can import audio level and pan information stored in an OMF file.

Exporting Sequence Audio to an OMF File

When you need to transfer your sequence audio to another audio post-production application, you can use the Export Audio to OMF command.

To export audio from a sequence to an OMF file
  1. Select a sequence in the Browser or open a sequence in the Timeline.

  2. In the Timeline, make sure that each audio track you want to export is enabled (the Track Visibility control next to the track is green).

    Figure. Timeline window showing the Track Visibility controls turned on for two tracks.
  3. Choose File > Export > Audio to OMF.

  4. In the OMF Audio Export dialog, choose the options you want, then click OK.

    Figure. OMF Audio Export dialog showing the Rate and Depth pop-up menus and the Handle Length field.
    • Rate: Choose a sample rate that suits what you’re using the audio for. All of the audio you export has the same sample rate. If you use audio with different sample rates, it’s converted.
    • Depth: Choose 16-bit or 24-bit. If you choose 24-bit audio, make sure the application you will use to import the OMF file supports 24-bit audio.

      Note: When exporting to OMF, Final Cut Pro uses the highest quality setting regardless of what you choose from the Audio Playback Quality pop-up menu in the General tab of the User Preferences window.

    • Handle Length: Enter a value in timecode format to add handles to the audio clips. Handles give your audio editor the flexibility needed to fix edits. Handles of 1 to 3 seconds are typical, but it’s best to check with your audio editor.

      Handles are included only when there is additional audio media outside the clip In and Out points. When there is not enough media to create the full handle duration, Final Cut Pro includes as much of a handle as possible.

    • Include Crossfade Transitions: Because some OMF importing tools do not handle cross fade transitions correctly, and many sound editors prefer to create cross fades themselves, you have the option to leave cross fades out when exporting your sequence as an OMF file. When this checkbox is deselected, extra source media is substituted for the duration of the cross fade being left out. How much extra source media is substituted depends on whether the cross fade was edited before, on, or after the edit point. Extra source media included as a result of this option is in addition to extra source media added by the Handle Length option.
    • Include Levels: Audio levels and keyframes are included in the exported OMF file. Even if no audio level keyframes are set, the current level of each clip is exported.
    • Include Pan: Pan settings and keyframes are included in the exported OMF file. Even if no pan keyframes are set, the current pan setting of each clip is exported.
  5. Choose a location and enter a name for the file.

  6. When you’re ready to export, click Save.

OMF Files Have a 2-Gigabyte Limit

OMF files that you create cannot be larger than 2 gigabytes. In most cases, this should not present a problem because 2 gigabytes will accommodate approximately 7 hours of mono audio media (depending on the bit depth and sample rate of your audio). If your sequence exceeds this limit, you will see a warning message before exporting begins.