Audio Units allow sound files with different options like audio time stretching and pitch scaling (e.g.timestretch), sample rate conversion, and streaming over a Local Area Network. It comes with a set of AU plug-ins like EQ filters, dynamic processors, delay, reverb, and a Soundbank Synthesizer Instrument.
Audio Units are used in Apple applications such as GarageBand, Soundtrack Pro, Logic Express, Logic Pro, Logic Pro X, Final Cut Pro, audio software developed for macOS such as Amadeus Pro, Ardour, Audio Hijack, Digital Performer, REAPER, and Studio One.
Features of Audio Units
- Write/Read Access: There are three levels of access that offer read-only, write-only, and read/write.
- Scopes: The iOS platform supports the input, output, and global scopes for Audio Units.
- Data Type: Because Audio Units employ a programmatic data type, managing audio data may be done with more freedom.
Audio Unit Plug-Ins
A selection of built-in plug-ins that improve the functionality of audio applications are included with Audio Units:
- EQ filters: Modify the sound's various frequencies.
- Dynamic processors: Control the dynamics of sound, including compression.
- Reverb and delay: Enhance audio recordings with spatial effects.
- Soundbank Synthesizer Synthesized sound production for musical compositions is the instrument.
Applications Using Audio Units
Audio Units are essential to many macOS and Apple apps, including:
- GarageBand: A studio for making music.
- Logic Pro and Logic Pro X are sophisticated suites for audio production.
- Video editing software with built-in audio features is called Final Cut Pro.
- Amadeus Pro, Ardour, Audio Hijack, Digital Performer, REAPER, and Studio One are examples of third-party applications.
AU File Format Specifications
The AU file format uses a simple extensible header, followed by data. The minimum length of header is 28 bytes.
| Offset | Length | Type | Contents |
|---|---|---|---|
| 0 | 4 | character | File magic ".snd" |
| 4 | 4 | unsigned integer | Offset to start of data |
| 8 | 4 | unsigned integer | Number of bytes of data |
| 12 | 4 | unsigned integer | Data format code |
| 16 | 4 | unsigned integer | Sampling rate |
| 20 | 4 | unsigned integer | Number of channels |
| 24 | - | character | Optional text information (minimum 4 bytes) |
Advantages of Audio Units
- Versatility: Virtual instruments and audio effects are only two of the many audio jobs that AU plug-ins may be utilized for.
- Integration: By providing capabilities like loading virtual instruments (like Garritan instruments) and applying audio effects (like Ambience Reverb) without the need for separate programs, Audio Units provide seamless integration with Apple and third-party applications.
- Extensibility: Customizable metadata may be added to AU files by adding optional text content.
Disadvantages of Audio Units
- Editing in the project which contains Audio unit plug-ins can lead to timing issues.
- Maximum number of audio unit that can be used in a project depends on the device in use.
- Loading complex audio units can leads some time even on new devices.
Conclusion
Apple computers' Audio Units (AU) provide a robust foundation for audio processing that makes it possible to manipulate sound files in a flexible and effective manner. They have some advantages, such extension and integration, but they also have some drawbacks, like device limits and possible timing problems. In general, audio units are a useful tool for both enthusiasts and audio professionals.