Audiokinetic

AAC Parameters

In the AAC Parameters dialog box you can set specific properties for AAC. AAC has the following limitations and characteristics:

Files: The AAC audio format only supports mono, stereo, 0.1, 1.1, 5.0 and 5.1 files. Other channel configurations are downmixed.
Looping and sample accuracy: Looping across the whole file or within regions is supported. However, the encoding process tends to shift the audio content and/or add padding frames, which may cause artifacts when used in a context where sample-accuracy is needed, for example with interactive music, or in continuous random-sequence containers with sample-accurate transitions.
Run-time characteristics: On iOS, AAC sound use hardware-assisted decoding if available. The hardware may only decode one AAC sound at a time. Note that the audio thread CPU usage displayed by Wwise will appear to be very large, but most of this time is actually spent by the hardware decoder, therefore yielding CPU time to other processes. On the other hand, software decoding on iOS is very costly and should be avoided.
Latency: Setup time of AAC voices may be fairly long, especially on iOS, and sometimes also with streamed files on the Mac. Additionally, starting an AAC voice on iOS may cause voice starvation.
Authoring: Currently, AAC sounds cannot be previewed in the Wwise authoring tool.

	Note
	Apple QuickTime 7.6.5 or later is required for AAC conversion.

Interface Element

Description

AAC Encoding Parameters

Quality

Specifies the resulting AAC encoding quality. With most encoding modes, quality maps to a given bitrate. This bitrate is indicated inside the dialog box, next to the quality slider. Higher quality values result in better audio quality at the expense of longer files and increased CPU usage.

Units: None.
Range: 1-16.

Mode

Specifies the AAC encoding mode.

Units: None.

Values: Constant Bitrate, Average Bitrate, Constrained Variable Bitrate and True Variable Bitrate.

Compression

Specifies the AAC encoding compression level. Lower settings result in faster encoding, but reduced audio quality. Using the highest setting is recommended.

Units: None.
Values: Very Low (larger files / fastest), Low, Medium, High, Very High (smaller files / slowest).