Sound_Mode 1 (changes)
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Programmer's SoundDMA Reference Manuals
» Part 15 – SWI Calls
» Sound Sound_Mode
» Sound_Mode 1Sound_Mode
» Sound_Mode 1
Sound_Mode 1
(SWI &40144)
| Entry | |
|---|---|
| R0 | 1 (reason code) |
| R1 | New oversampling state: |
| 0 → disable oversampling | |
| Non-zero → use oversampling where possible |
| Exit | |
|---|---|
| R1 | Previous oversampling state (0=disabled, 1=enabled) |
Use
This SWI is used to control whether automatic oversampling of sound output should be performed.
Notes
If oversampling is enabled, and certain hardware/software requirements are met, then all sound output (8 bit and 16 bit) will be 2x oversampled via linear interpolation. Generally speaking, oversampling will be used if the following requirements are met:
- Oversampling is enabled via this call
- The desired sample rate is under 24kHz
- The hardware supports both the requested sample rate and 2x the requested sample rate
- The buffer size used for 16 bit sound is 2KB or smaller (to allow the oversampled buffer to fit in one 4KB page)
Sound_Mode 0 can be used to read the oversampling state without changing it.
See also
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