Cafe Sound System Overview



AX is the heart of the Cafe sound system. AX is a thin, low-level driver that provides the following:

The remaining audio libraries in the SDK are optional. They build on the functionality of the AX library.

For more information about the Cafe audio features, see Sound Technical Features.

For information about how AX is executed in the context of the Cafe system and how application code interacts with AX, see the AX Programming Model.

For information about the AX voice generation and mixer procedures, see the AX Rendering Model.


The AXFX module provides Reverb, Delay, and Chorus effects for AX. These are implemented as PCC application processor algorithms and applied using the AX AUX buses. Use these premade effects to help you create custom effects, and apply them as needed.

For more information about AXFX, see AX AUX Bus Effects Overview.


MIX is an abstraction layer for AX that provides panning, surround panning, and fader controls for AX voices.

For more information about MIX, see Mixer Overview.


The AX Articulator (AXART) library builds upon the MIX abstraction, providing more complex controls for mixing. With AXART, you may apply any number of articulators to a single voice to achieve volume, pan, pitch, LFO, envelope, and 3D sound effects.

For more information about AXART, see Voice Articulator Overview.


The SYN library provides synthesizer functionality. It may be used with SEQ to play standard MIDI files.

For more information about SYN, see Synthesizer Overview.


The SEQ library provides sequencing functionality. It may be used with SYN to play standard MIDI files.

For more information about SEQ, see Sequencer Overview.

A new and enhanced sound-2 library is released recently with a set of new features and performance improvements. It will replace the legacy sound-1 library after a short-term transition period. Developers are highly recommended to use the new sound-2 library. Refer to Sound Library for more information.


The Cafe SDK provides a set of applications that demonstrate how to use the provided libraries. For information about the demos, see the Sound System Demos.

Tool Chain


The DSPADPCM tool compresses audio files into DSP-ADPCM format. The DSP tool in Cafe supports decompression of this format allowing the DSP to take the decompression processing load from the CPU.

For more information, see the DSPADPCM Overview.


The Sound Pipeline (SP) provides PC-based tools and runtime functions that manage sound samples for use with AX. The SP PC tools convert sets of standard sound files into binary packages. The runtime functions pull audio data from these packages and set voices up to play it.

For more information about SP, see the Sound Pipeline Overview.


RPL Modules

The Cafe audio driver is two RPL modules that are required by Cafe audio system to function properly. Source code for the high-level AX application components (excluding the AXFX Effects Library) in snd_user.rpl is included. Developers may examine and customize this code as needed. Source code and PC tools may be found in the following folders that are located in the $CAFE_ROOT/system/src/demo/snd_user_rpl/ directory:

A makefile is included for rebuilding the snd_user.rpl module. Developers may create a customized version of snd_user.rpl to use instead of the one in the SDK. The recommended customization steps are:

Revision History

2013-10-30 Copy-edits.
2013-10-15 Added Organization section.
2013-05-08 Automated cleanup pass.
2013-02-15 Edit pass.
2012-08-01 Cleanup Pass.
2011-02-21 Initial version.