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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>
date Thu, 24 Aug 2006 12:10:46 +0000
parents 355632dca928
children
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>SDL_BuildAudioCVT</H1
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><H2
>Name</H2
>SDL_BuildAudioCVT&nbsp;--&nbsp;Initializes a SDL_AudioCVT structure for conversion</DIV
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>Synopsis</H2
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><P
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><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_BuildAudioCVT</B
></CODE
>(SDL_AudioCVT *cvt, Uint16 src_format, Uint8 src_channels, int src_rate, Uint16 dst_format, Uint8 dst_channels, int dst_rate);</CODE
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>Description</H2
><P
>Before an <A
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><SPAN
CLASS="STRUCTNAME"
>SDL_AudioCVT</SPAN
></A
> structure can be used to convert audio data it must be initialized with source and destination information. </P
><P
><TT
CLASS="PARAMETER"
><I
>src_format</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>dst_format</I
></TT
> are the source and destination format of the conversion. (For information on audio formats see <A
HREF="sdlaudiospec.html"
><SPAN
CLASS="STRUCTNAME"
> SDL_AudioSpec</SPAN
></A
>). <TT
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><I
>src_channels</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>dst_channels</I
></TT
> are the number of channels in the source and destination formats. Finally, <TT
CLASS="PARAMETER"
><I
>src_rate</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>dst_rate</I
></TT
> are the frequency or samples-per-second of the source and destination formats. Once again, see <A
HREF="sdlaudiospec.html"
><SPAN
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>SDL_AudioSpec</SPAN
></A
>.</P
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><H2
>Return Values</H2
><P
>Returns <SPAN
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>-1</SPAN
> if the filter could not be built or 1 if it could.</P
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>Examples</H2
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>See <A
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><TT
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>SDL_ConvertAudio</TT
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>.</P
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>SDL_ConvertAudio</TT
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