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Sam Lantinga - Sun Jul 2 14:16:44 PDT 2000
 * Added support for the Ogg Vorbis music format: http://www.vorbis.org/
 * Cleaned up the streaming wave code a bit
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Sam Lantinga committed Jul 3, 2000
1 parent 7adf3f7 commit 9c21f8e47ef58e80548769e98d95ea986cae769f

File 6 of 9 in 9c21f8e

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/*
MIXERLIB: An audio mixer library based on the SDL library
Copyright (C) 1997-1999 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
5635-34 Springhouse Dr.
Pleasanton, CA 94588 (USA)
slouken@devolution.com
*/

#ifdef OGG_MUSIC

/* This file supports Ogg Vorbis music streams */

#include <stdio.h>
#include <string.h>

#include "SDL_mixer.h"
#include "music_ogg.h"

/* This is the format of the audio mixer data */
static SDL_AudioSpec mixer;

/* Initialize the Ogg Vorbis player, with the given mixer settings
This function returns 0, or -1 if there was an error.
*/
int OGG_init(SDL_AudioSpec *mixerfmt)
{
mixer = *mixerfmt;
return(0);
}

/* Set the volume for an OGG stream */
void OGG_setvolume(OGG_music *music, int volume)
{
music->volume = volume;
}

/* Load an OGG stream from the given file */
OGG_music *OGG_new(const char *file)
{
OGG_music *music;
FILE *fp;

music = (OGG_music *)malloc(sizeof *music);
if ( music ) {
/* Initialize the music structure */
memset(music, 0, (sizeof *music));
OGG_stop(music);
OGG_setvolume(music, MIX_MAX_VOLUME);
music->section = -1;

fp = fopen(file, "rb");
if ( fp == NULL ) {
SDL_SetError("Couldn't open %s", file);
free(music);
return(NULL);
}
if ( ov_open(fp, &music->vf, NULL, 0) < 0 ) {
SDL_SetError("Not an Ogg Vorbis audio stream");
free(music);
fclose(fp);
return(NULL);
}
} else {
SDL_OutOfMemory();
}
return(music);
}

/* Start playback of a given OGG stream */
void OGG_play(OGG_music *music)
{
music->playing = 1;
}

/* Return non-zero if a stream is currently playing */
int OGG_playing(OGG_music *music)
{
return(music->playing);
}

/* Read some Ogg stream data and convert it for output */
static void OGG_getsome(OGG_music *music)
{
int section;
int len;
char data[4096];
SDL_AudioCVT *cvt;

len = ov_read(&music->vf, data, sizeof(data), 0, 2, 1, &section);
if ( len <= 0 ) {
if ( len == 0 ) {
music->playing = 0;
}
return;
}
cvt = &music->cvt;
if ( section != music->section ) {
vorbis_info *vi;

vi = ov_info(&music->vf, -1);
SDL_BuildAudioCVT(cvt, AUDIO_S16, vi->channels, vi->rate,
mixer.format,mixer.channels,mixer.freq);
if ( cvt->buf ) {
free(cvt->buf);
}
cvt->buf = (Uint8 *)malloc(sizeof(data)*cvt->len_mult);
music->section = section;
}
if ( cvt->buf ) {
memcpy(cvt->buf, data, len);
if ( cvt->needed ) {
cvt->len = len;
SDL_ConvertAudio(cvt);
} else {
cvt->len_cvt = len;
}
music->len_available = music->cvt.len_cvt;
music->snd_available = music->cvt.buf;
} else {
SDL_OutOfMemory();
music->playing = 0;
}
}

/* Play some of a stream previously started with OGG_play() */
void OGG_playAudio(OGG_music *music, Uint8 *snd, int len)
{
int mixable;

while ( (len > 0) && music->playing ) {
if ( ! music->len_available ) {
OGG_getsome(music);
}
mixable = len;
if ( mixable > music->len_available ) {
mixable = music->len_available;
}
if ( music->volume == MIX_MAX_VOLUME ) {
memcpy(snd, music->snd_available, mixable);
} else {
SDL_MixAudio(snd, music->snd_available, mixable,
music->volume);
}
music->len_available -= mixable;
music->snd_available += mixable;
len -= mixable;
snd += mixable;
}
}

/* Stop playback of a stream previously started with OGG_play() */
void OGG_stop(OGG_music *music)
{
music->playing = 0;
}

/* Close the given OGG stream */
void OGG_delete(OGG_music *music)
{
if ( music ) {
if ( music->cvt.buf ) {
free(music->cvt.buf);
}
ov_clear(&music->vf);
free(music);
}
}

#endif /* OGG_MUSIC */

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