The Mode Descriptors

The files in `DEVS:AudioModes' describes the available audio modes that you can chose from in the audio mode requester. All files located in this drawer will be scanned the first time AHI is used, and added to the internal mode database.

The following modes are available for most drivers:

`Mono'

Mono output, all sounds will be centered, and no surround sound is possible.

`Stereo'

Stereo output, but all sounds are either forces to the extreme left or extreme right--centered sounds are not possible, for example. This mode will probably use slightly more CPU power than the "mono" mode. Since all sounds are forced to one of the extreme positions, stereo sounds will play with either the left or the right part muted.

`Stereo++'

Stereo output with free positioning of all sounds--an instrument can be placed anywhere between the two speakers, for example. Unless the program only uses the extremes when positioning a sound, this mode will eat more CPU cycles than the "stereo" mode.

`Fast mono'

`Fast stereo'

`Fast stereo++'

"Fast" modes take some shortcuts in order to reduce the CPU usage. For 8 bit samples, multiplication tables will be used, which speeds up mixing by magnitudes and still gives the same quality with the exception of volume levels--instead of 256 levels only 32 are available. The disadvantage of multiplication tables is that they require a fair amount of free RAM. For 16 bit samples, the shortcuts are a bit more crude: the volume of each sound will be rounded to a power of 2 before it's played. This means that a 16 bit sound will only be played at volume levels of 100%, 50%, 25%, 12.5% etc. If surround sounds are played, the normal (not "fast") mixing routines will be used. You can use the preferences program (see section `Advanced settings' Page) to disable surround sounds for "fast" modes. "Fast" modes are useful if you wish to use as little CPU power as possible, but don't mind spending some memory to reach that goal. They are also very useful when playing 16 bit audio streams--from a sample or MPEG player, for example--since that usually doesn't involve volume scaling and frequency recalculation. However, if used for playing streams, make sure the mixing frequency is the same as the stream frequency!

`HiFi mono'

`HiFi stereo'

`HiFi stereo++'

"HiFi" modes use much better mixing algorithms than the other modes, using 32 bits internally and linear interpolation. They are also much slower than the other modes. "HiFi" modes turn on master volume with clipping automatically (see section `Advanced settings' Page). "HiFi" modes are useful when you're playing music---MIDI songs or modules, for example--and want the best possible quality AHI has to offer.

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