author Ryan C. Gordon
Thu, 24 Aug 2006 12:10:46 +0000
changeset 1982 3b4ce57c6215
parent 1895 c121d94672cb
child 2049 5f6550e5184f
child 3797 9dc81c6acaf5
permissions -rw-r--r--
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/ 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.
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2006 Sam Lantinga
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Lesser General Public
     7     License as published by the Free Software Foundation; either
     8     version 2.1 of the License, or (at your option) any later version.
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    13     Lesser General Public License for more details.
    15     You should have received a copy of the GNU Lesser General Public
    16     License along with this library; if not, write to the Free Software
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    19     Sam Lantinga
    21 */
    22 #include "SDL_config.h"
    24 #ifndef _SDL_lowaudio_h
    25 #define _SDL_lowaudio_h
    27 #include "../SDL_sysaudio.h"
    29 /* Hidden "this" pointer for the video functions */
    30 #define _THIS	SDL_AudioDevice *this
    32 struct SDL_PrivateAudioData
    33 {
    34     /* The file descriptor for the audio device */
    35     int audio_fd;
    37     SDL_AudioFormat audio_fmt;  /* The app audio format */
    38     Uint8 *mixbuf;              /* The app mixing buffer */
    39     int ulaw_only;              /* Flag -- does hardware only output U-law? */
    40     Uint8 *ulaw_buf;            /* The U-law mixing buffer */
    41     Sint32 written;             /* The number of samples written */
    42     int fragsize;               /* The audio fragment size in samples */
    43     int frequency;              /* The audio frequency in KHz */
    44 };
    46 /* Old variable names */
    47 #define audio_fd		(this->hidden->audio_fd)
    48 #define audio_fmt		(this->hidden->audio_fmt)
    49 #define mixbuf			(this->hidden->mixbuf)
    50 #define ulaw_only		(this->hidden->ulaw_only)
    51 #define ulaw_buf		(this->hidden->ulaw_buf)
    52 #define written			(this->hidden->written)
    53 #define fragsize		(this->hidden->fragsize)
    54 #define frequency		(this->hidden->frequency)
    56 #endif /* _SDL_lowaudio_h */
    57 /* vi: set ts=4 sw=4 expandtab: */