Miles Sound System SDK 7.2a

Sound under Xbox

Discussion

For digital audio output, Miles for Xbox uses the DirectSound system library. Miles is carefully designed to use the powerful built-in hardware on the Xbox to its fullest. You can play hundreds of digital samples at once with no CPU hit at all!

The Miles Sound System on Xbox supports uncompressed, IMA ADPCM, MP3, Ogg Vorbis, and Xbox ADPCM digital sound. IMA, MP3, and Ogg Vorbis are not natively supported by the Xbox, but Miles makes the decompression and streaming to the sound hardware seamless - they just take a little more CPU. In particular, our IMA ADPCM and MP3 decompressors are optimized for the Xbox - MP3 decompression is almost three times faster than WMA compression, for example. Even better, Xbox ADPCM takes no CPU at all to decompress!

Miles on the Xbox also has integrated 2D and 3D sound subsystems. (Note that 3D positioning support works even if you don't open the Xbox driver with the AIL_OPEN_DIGITAL_NEED_HW_3D flag. It's faster if you use hardware 3D positioning, but a driver opened with AIL_OPEN_DIGITAL_NEED_HW_3D makes fewer voices available to the application and won't support certain features like stereo samples and streams.)

The Xbox also supports full 5.1 discrete audio. You can set the volume levels of the 5.1 individual channels with the AIL_set_sample_51_volume_pan or AIL_set_sample_51_volume_levels functions.

The Xbox doesn't have dedicated MIDI hardware, so Miles uses its built-in DLS synthesizer for all MIDI playback. This has the added advantage of allowing you to author custom DLS instrument sets to optimize memory use.

And that's pretty much it - Miles is a piece of cake to use on the Xbox.

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Group: Overview for Microsoft Xbox
Related Functions: AIL_set_sample_51_volume_levels, AIL_set_sample_51_volume_pan