Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_MixAudio.3 @ 1982:3b4ce57c6215
First shot at new audio data types (int32 and float32).
Notable changes:
- Converters between types are autogenerated. Instead of making multiple
passes over the data with seperate filters for endianess, size, signedness,
etc, converting between data types is always one specialized filter. This
simplifies SDL_BuildAudioCVT(), which otherwise had a million edge cases
with the new types, and makes the actually conversions more CPU cache
friendly. Left a stub for adding specific optimized versions of these
routines (SSE/MMX/Altivec, assembler, etc)
- Autogenerated converters are built by SDL/src/audio/sdlgenaudiocvt.pl. This
does not need to be run unless tweaking the code, and thus doesn't need
integration into the build system.
- Went through all the drivers and tried to weed out all the "Uint16"
references that are better specified with the new SDL_AudioFormat typedef.
- Cleaned out a bunch of hardcoded bitwise magic numbers and replaced them
with new SDL_AUDIO_* macros.
- Added initial float32 and int32 support code. Theoretically, existing
drivers will push these through converters to get the data they want to
feed to the hardware.
Still TODO:
- Optimize and debug new converters.
- Update the CoreAudio backend to accept float32 data directly.
- Other backends, too?
- SDL_LoadWAV() needs to be updated to support int32 and float32 .wav files
(both of which exist and can be generated by 'sox' for testing purposes).
- Update the mixer to handle new datatypes.
- Optionally update SDL_sound and SDL_mixer, etc.
author | Ryan C. Gordon <icculus@icculus.org> |
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date | Thu, 24 Aug 2006 12:10:46 +0000 |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
rev | line source |
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1 .TH "SDL_MixAudio" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" |
0 | 2 .SH "NAME" |
3 SDL_MixAudio\- Mix audio data | |
4 .SH "SYNOPSIS" | |
5 .PP | |
6 \fB#include "SDL\&.h" | |
7 .sp | |
8 \fBvoid \fBSDL_MixAudio\fP\fR(\fBUint8 *dst, Uint8 *src, Uint32 len, int volume\fR); | |
9 .SH "DESCRIPTION" | |
10 .PP | |
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11 This function takes two audio buffers of \fBlen\fR bytes each of the playing audio format and mixes them, performing addition, volume adjustment, and overflow clipping\&. The \fBvolume\fR ranges from 0 to \fBSDL_MIX_MAXVOLUME\fP and should be set to the maximum value for full audio volume\&. Note this does not change hardware volume\&. This is provided for convenience -- you can mix your own audio data\&. |
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12 .PP |
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13 .RS |
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14 \fBNote: |
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15 .PP |
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16 Do not use this function for mixing together more than two streams of sample data\&. The output from repeated application of this function may be distorted by clipping, because there is no accumulator with greater range than the input (not to mention this being an inefficient way of doing it)\&. Use mixing functions from SDL_mixer, OpenAL, or write your own mixer instead\&. |
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17 .RE |
0 | 18 .SH "SEE ALSO" |
19 .PP | |
20 \fI\fBSDL_OpenAudio\fP\fR | |
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21 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58 |