# Import Filtering and Importer Order

### From Audacity Development Manual

## Using the Files of type: ... or Format dropdown menu in the Open and Import Audio Dialogs

The choice made in the "Files of type:" (Windows) or "Format" (Mac OS/X) dropdown menu in these dialogs does two things.

1. It restricts the file list to files of that type (or those supported by that importer), according to the file extension.
2. It chooses which importer to use.

The choices in the "Files of type:" or "Format" dropdown menu are:

- All files
  - All files in the list are selectable, even those not supported by Audacity or FFmpeg
  - The built-in Audacity importers will be tried first, then FFmpeg (if installed)
- All supported files
  - Only those files supported by Audacity or FFmpeg (if installed) are selectable
  - The built-in Audacity importers will be tried first, then FFmpeg
- Audacity Projects - This option is available only when you use the File > Open command
  - Only Audacity project files (.aup) are selectable
  - No importer is involved, since you are opening an Audacity project, not importing an audio file
- WAV, AIF and other uncompressed types
  - Only uncompressed files are selectable
  - The built-in Audacity importers will be tried first, then FFmpeg (if installed)
    - If the built-in Audacity importers are used and "read directly" is chosen in Import / Export Preferences then On-Demand Loading will be used. If the FFmpeg importer is used, On-Demand Loading will not be used.
- Ogg vorbis files, FLAC files, MP3 files
  - Only files of the specified type are selectable
  - The built-in Audacity importers will be tried first, then FFmpeg (if installed)
- List of files in basic text format
  - Only files ending in .lof are selectable. See LOF Files for how to create and use LOF files.
  - The importer used will depend on the files pointed to by the LOF file.
- FFmpeg compatible files - this option is only available if you have installed the optional FFmpeg extension.
  - Any file types supported by FFmpeg are selectable
  - The FFmpeg importer will always be tried first if "Attempt to use filter in OpenFile dialog first" in Extended Import Preferences is checked, otherwise the native importer will be tried first.
    - Note that if this option is chosen and an uncompressed file type is selected from the list, On-Demand Loading will not be used.
- QuickTime files - Mac only
  - Any file type supported by QuickTime is selectable
  - QuickTime will be used to decode the file and send it to Audacity

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