Many video editors assume all the roles of a post-production team, such as motion graphics, color correction, and audio mixing. While it is important to be knowledgeable in all of these areas, it is hard to become an expert in everything. Budget permitting, editors are sometimes fortunate enough to collaborate with other professionals with dedicated skillsets.

If you are working with a sound engineer or an audio mixer, you need to know how to share files with them in the best workflow. Many audio mixers today prefer OMFs, which are essentially packaged audio projects. OMF (formerly OMFI) stands for Open Media Framework Interchange, which is a file format designed specifically for transferring digital media between different software applications.

 

 

Advantages Of OMFs

Before OMFs, it was common practice to export isolated audio stems to share with collaborators. That meant more time spent exporting and importing audio, a greater chance of error, and less creative control. Below are the main advantages of an OMF workflow.

  • Retains Highest Quality

OMFs use the WAV or AIFF file types, which are industry-standard uncompressed formats. This means you are guaranteed to use the proper format instead of being faced with more options such as MP3 or M4a, which compress your audio and cause quality loss.

OMFs allow up to 24 bit depth, which is usually the highest quality audio is recorded. The audio waveform of an audio recording is more precise when the bit depth is higher, allowing for finer details and nuanced fluctuations in sound levels.

 

  • Quick & Easy

With the right timeline organization, you can export an OMF in just a few clicks. If you can get in the habit of keeping your audio grouped together by type (dialogue, music, sfx, etc), you won’t have any extra work to do before exporting an OMF.

 

  • Includes Basic Automation

All that work you did with the Pen Tool to duck audio and adjust levels gets transferred to your collaborators! This saves them time (which usually saves you money) and also serves as a non-verbal communication of your creative vision for the audio mix. Panning data is also included.

 

  • Non-Destructive

Since the OMF is robust enough to include volume and panning automation, the original audio remains untouched. Your volume adjustments can be altered or removed at any point, which means that your audio mixer can choose to start from scratch with the highest quality source material.

 

Limitations Of OMFs

  • File Size

The total file size limit for an OMF is 2 GB. While this isn’t an issue for shorter-form edits like commercials and online videos, it can be problematic for feature films, documentaries, and projects with a lot of audio tracks. AAFs* have been designed to overcome this limitation.

 

  • Audio Effects

The majority of audio effects won’t be transferred between programs. For example, if you’ve applied an EQ and reverb effect to some music or sound effects, those effects won’t carry on to programs like Pro Tools or Logic.

 

Preparing Your Timeline

There are a few basic steps to take before exporting an OMF that will make the file interchange process smoother.

  1. Organize your timeline by audio type. Remember that the audio mixer won’t be nearly as familiar with the project as you are, so it is part of your job to lay things out intelligibly.
  2. Set your in and out points to the same timecodes that you’ll use to export your video. This step will influence how the audio clips line up for your mixer.
  3. Remove excess or unneeded audio. Is there a bunch of clips to the right of your out point? What about muted clips in your working area? Deleting anything that might be confusing or extraneous will usually make life easier for the sound mixer. Remember to duplicate your sequence or save a new version of your project in case you need to access previous work. 

 

Exporting An OMF

Once your timeline is organized and cleaned up, you’re now ready to export an OMF.

Click File → Export → OMF. This will bring up the OMF setting dialogue


 

 

Name your OMF. It is usually a good idea to name it identically to your sequence or version.

Choose the sample rate to match your source material. 99% of the time, 48000 Hz will be the right choice.

Choose bit depth. Look at the properties of your audio clips to see what bit depth they have (either 16 or 24). If everything is 16, then that should be your selection. If some clips are 24, or you simply are not sure, select 24 to preserve all the quality form the source recording.

Embed Audio vs. Separate Audio. Embedding audio will package everything neatly into a single OMF file, which is the easiest option. Use the Separate Audio option if your project exceeds the 2 GB limitation.

Trim vs. Copy Audio Files. Trimming audio files will include just the edits in the timeline, while copying audio files provides the sound mixer with the entire source recording. This option trades off file sizes for more source material.

Handle Frames determine how much extra audio to include on either side of a trimmed clip. Increasing the handle size gives an audio mixer more flexibility to work with.

Include Pan –– leave this checked unless you specifically don’t want to share panning information with your mixer.

 

The final step after creating your OMF is to export an accompanying reference video. Audio mixers will then import both the OMF and the video into their software application. It is best practice to keep reference videos small and lightweight so that programs like Pro Tools don’t have to spend valuable computing resources on playing a large video.

* AAF (Advanced Authoring Format) is the successor to OMF and retains even more data between programs. However, it is not yet as reliable across all platforms and operating systems as OMFs, so it is best to ask your audio mixer which file type he/she prefers. The process for exporting an AAF in Premiere is nearly identical to OMFs.