By default X2Pro will extract the audio from your media files and embed it all in your AAF.  The advantages of using this method are numerous, for example:

• You will have a single file containing everything you need to work with the audio in Pro Tools. This single file can easily be moved between machines (e.g. sent to a different location for audio finishing).
• When the file is opened in Pro Tools, all the audio will be automatically extracted from the AAF and the user will not need to do any relinking.
• Pro Tools will be able to access all the audio because X2Pro will have converted it all to single-channel PCM.

X2Pro can be set to reference WAV audio instead of embedding it the AAF. This can result in a smaller AAF file, and may be necessary for some DAWs, but the clips must be relinked when the AAF is opened. Obviously if the media is not available on the machine that opens the AAF, it will not be possible to relink.

Because of limitations in various DAWs (including Pro Tools), X2Pro will not reference any non-WAV audio (and by default will not reference multi-channel WAV files either).

When X2Pro encounters media that can’t be referenced, the default behaviour is for X2Pro to embed the audio in the AAF. This setting can be changed in the preferences, so that X2Pro will not create the AAF and will instead show an error message explaining what clips couldn’t be referenced.

The error message “not a WAV file or too many audio channels” means that

• X2Pro is set to “Reference WAV files in place”
• X2Pro is set to “Generate an error and don’t create AAF file” when encountering media that can’t be referenced
• Your project contains audio that X2Pro is not able to reference. For example a mov/r3d file, or a multi-channel WAV file if X2Pro is set to not “Reference multi-channel WAV files”.

There are a few ways of getting past this error message:

1. Uncheck the option to "Reference WAV files in place" (this is the default setting). This will mean all audio is embedded in the AAF file. The AAF file will be larger than if you were to reference the WAV files, but it will be much easier to open in Pro Tools because you won't have manually link clips to WAV files when you open the AAF. It will also be easier to send the AAF elsewhere for finishing because it will contain all the audio and your project in a single file.
2. Under "Handling media that can't be referenced" in the preferences, choose to "Embed the media, optionally trimming" (this is the default setting). With this option selected, audio that can be referenced will be, and all other audio will be embedded in the AAF. This will ensure that Pro Tools or any other DAW is able to access all the audio that you have used in your project.
3. If your audio is all WAV, but some/all of the WAV files are multi-channel and you know that your DAW can handle multi-channel referenced WAV files (Pro Tools can’t), you can change a setting in the X2Pro preferences to “Reference multi-channel WAV files”. You should only use this option if you know that your DAW supports multi channel WAV files. Pro Tools 10 does not.
4. If your project contains audio from a mix of WAVs and other file types (even if the audio from non-WAV files is silent), but you are only interested in the WAV audio; disable all the non-wav audio in your FCP X project before exporting the FCPXML and set X2Pro to “Discard disabled clips”