SDL_mixer: An audio mixer library based on the SDL library

Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>

This software is provided 'as-is', without any express or implied

warranty. In no event will the authors be held liable for any damages

arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,

including commercial applications, and to alter it and redistribute it

freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not

claim that you wrote the original software. If you use this software

in a product, an acknowledgment in the product documentation would be

appreciated but is not required.

2. Altered source versions must be plainly marked as such, and must not be

misrepresented as being the original software.

3. This notice may not be removed or altered from any source distribution.

This is the source needed to decode an AIFF file into a waveform.

It's pretty straightforward once you get going. The only

externally-callable function is Mix_LoadAIFF_RW(), which is meant to

act as identically to SDL_LoadWAV_RW() as possible.

This file by Torbjörn Andersson (torbjorn.andersson@eurotime.se)

8SVX file support added by Marc Le Douarain (mavati@club-internet.fr)

in december 2002.

*/

#include "SDL_mixer.h"

#include "load_aiff.h"

/*********************************************/

/* Define values for AIFF (IFF audio) format */

/*********************************************/

#define FORM 0x4d524f46 /* "FORM" */

#define AIFF 0x46464941 /* "AIFF" */

#define SSND 0x444e5353 /* "SSND" */

#define COMM 0x4d4d4f43 /* "COMM" */

#define _8SVX 0x58565338 /* "8SVX" */

#define VHDR 0x52444856 /* "VHDR" */

#define BODY 0x59444F42 /* "BODY" */

/* This function was taken from libsndfile. I don't pretend to fully

* understand it.

*/

static Uint32 SANE_to_Uint32 (Uint8 *sanebuf)

{

/* Is the frequency outside of what we can represent with Uint32? */

if ( (sanebuf[0] & 0x80) || (sanebuf[0] <= 0x3F) || (sanebuf[0] > 0x40)

|| (sanebuf[0] == 0x40 && sanebuf[1] > 0x1C) )

return 0;

return ((sanebuf[2] << 23) | (sanebuf[3] << 15) | (sanebuf[4] << 7)

| (sanebuf[5] >> 1)) >> (29 - sanebuf[1]);

}

/* This function is based on SDL_LoadWAV_RW(). */

SDL_AudioSpec *Mix_LoadAIFF_RW (SDL_RWops *src, int freesrc,

SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len)

{

int was_error;

int found_SSND;

int found_COMM;

int found_VHDR;

int found_BODY;

Uint32 chunk_type;

Uint32 chunk_length;

long next_chunk;

/* AIFF magic header */

Uint32 FORMchunk;

Uint32 AIFFmagic;

/* SSND chunk */

Uint32 offset;

Uint32 blocksize;

/* COMM format chunk */

Uint16 channels = 0;

Uint32 numsamples = 0;

Uint16 samplesize = 0;

/* Make sure we are passed a valid data source */

was_error = 0;

if ( src == NULL ) {

was_error = 1;

goto done;

}

FORMchunk = SDL_ReadLE32(src);

chunk_length = SDL_ReadBE32(src);

if ( chunk_length == AIFF ) { /* The FORMchunk has already been read */

AIFFmagic = chunk_length;

chunk_length = FORMchunk;

FORMchunk = FORM;

} else {

AIFFmagic = SDL_ReadLE32(src);

}

if ( (FORMchunk != FORM) || ( (AIFFmagic != AIFF) && (AIFFmagic != _8SVX) ) ) {

SDL_SetError("Unrecognized file type (not AIFF nor 8SVX)");

was_error = 1;

goto done;

}

/* TODO: Better santity-checking. */

found_SSND = 0;

found_COMM = 0;

found_VHDR = 0;

found_BODY = 0;

do {

chunk_type = SDL_ReadLE32(src);

chunk_length = SDL_ReadBE32(src);

next_chunk = SDL_RWtell(src) + chunk_length;

/* Paranoia to avoid infinite loops */

if (chunk_length == 0)

break;

switch (chunk_type) {

case SSND:

found_SSND = 1;

offset = SDL_ReadBE32(src);

blocksize = SDL_ReadBE32(src);

start = SDL_RWtell(src) + offset;

break;

case COMM:

found_COMM = 1;

channels = SDL_ReadBE16(src);

numsamples = SDL_ReadBE32(src);

samplesize = SDL_ReadBE16(src);

SDL_RWread(src, sane_freq, sizeof(sane_freq), 1);

frequency = SANE_to_Uint32(sane_freq);

if (frequency == 0) {

SDL_SetError("Bad AIFF sample frequency");

was_error = 1;

goto done;

}

break;

case VHDR:

found_VHDR = 1;

SDL_ReadBE32(src);

SDL_ReadBE32(src);

SDL_ReadBE32(src);

frequency = SDL_ReadBE16(src);

channels = 1;

samplesize = 8;

break;

case BODY:

found_BODY = 1;

numsamples = chunk_length;

start = SDL_RWtell(src);

break;

default:

break;

}

/* a 0 pad byte can be stored for any odd-length chunk */

if (chunk_length&1)

next_chunk++;

} while ( ( ( (AIFFmagic == AIFF) && ( !found_SSND || !found_COMM ) )

|| ( (AIFFmagic == _8SVX ) && ( !found_VHDR || !found_BODY ) ) )

SDL_SetError("Bad AIFF (no SSND chunk)");

was_error = 1;

goto done;

}

SDL_SetError("Bad AIFF (no COMM chunk)");

was_error = 1;

goto done;

}

if ( (AIFFmagic == _8SVX) && !found_VHDR ) {

SDL_SetError("Bad 8SVX (no VHDR chunk)");

was_error = 1;

goto done;

}

if ( (AIFFmagic == _8SVX) && !found_BODY ) {

SDL_SetError("Bad 8SVX (no BODY chunk)");

was_error = 1;

goto done;

}

/* Decode the audio data format */

memset(spec, 0, sizeof(*spec));

spec->freq = frequency;

switch (samplesize) {

case 8:

spec->format = AUDIO_S8;

break;

case 16:

spec->format = AUDIO_S16MSB;

break;

default:

SDL_SetError("Unsupported AIFF samplesize");

was_error = 1;

goto done;

}

spec->channels = (Uint8) channels;

spec->samples = 4096; /* Good default buffer size */

*audio_len = channels * numsamples * (samplesize / 8);

if ( *audio_buf == NULL ) {

SDL_SetError("Out of memory");

return(NULL);

}

if ( SDL_RWread(src, *audio_buf, *audio_len, 1) != 1 ) {

SDL_SetError("Unable to read audio data");

return(NULL);

}

/* Don't return a buffer that isn't a multiple of samplesize */

*audio_len &= ~((samplesize / 8) - 1);

done:

if ( freesrc && src ) {

SDL_RWclose(src);

}

if ( was_error ) {

spec = NULL;

}

return(spec);

}