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MadWrapper.cpp
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MadWrapper.cpp
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/* -*- C++ -*-
*
* MadWrapper.cpp - SMPEG compatible wrapper functions for MAD: Mpeg Audio Decoder
*
* Copyright (c) 2001-2005 Ogapee. All rights reserved.
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "MadWrapper.h"
#include <mad.h>
#define DEFAULT_AUDIOBUF 4096
#define INPUT_BUFFER_SIZE (5*8192)
static inline unsigned short MadFixedToUshort( mad_fixed_t Fixed )
{
if (Fixed >= MAD_F_ONE)
Fixed = MAD_F_ONE - 1;
else if (Fixed < -MAD_F_ONE)
Fixed = -MAD_F_ONE;
Fixed = Fixed >> (MAD_F_FRACBITS-15);
return ((unsigned short)Fixed);
}
struct _MAD_WRAPPER{
SDL_RWops *src;
Uint32 length;
struct mad_stream Stream;
struct mad_frame Frame;
struct mad_synth Synth;
bool is_playing;
int volume;
unsigned char *input_buf;
unsigned char *output_buf;
long output_buf_index;
};
typedef struct _MAD_WRAPPER MAD_WRAPPER;
static MAD_WRAPPER* init( SDL_RWops *src )
{
MAD_WRAPPER *mad = new MAD_WRAPPER;
SDL_RWseek( src, 0, SEEK_END );
mad->length = SDL_RWtell( src );
SDL_RWseek( src, 0, SEEK_SET );
mad->src = src;
mad_stream_init( &mad->Stream );
mad_frame_init( &mad->Frame );
mad_synth_init( &mad->Synth );
mad->volume = 64;
mad->input_buf = new unsigned char[ INPUT_BUFFER_SIZE ];
mad->output_buf = new unsigned char[ 1152*4*5 ]; /* 1152 because that's what mad has as a max; *4 because */
mad->output_buf_index = 0;
mad->is_playing = false;
return mad;
}
MAD_WRAPPER* MAD_WRAPPER_new( const char *file, void* info, int sdl_audio )
{
SDL_RWops *src;
src = SDL_RWFromFile( file, "rb" );
if ( !src ) return NULL;
return init( src );
}
MAD_WRAPPER* MAD_WRAPPER_new_rwops( SDL_RWops *src, void* info, int sdl_audio )
{
return init( src );
}
int MAD_WRAPPER_playAudio( void *userdata, Uint8 *stream, int len )
{
MAD_WRAPPER *mad = (MAD_WRAPPER*)userdata;
if ( !mad->is_playing ) return -1; // pause
size_t ReadSize = 1, Remaining;
unsigned char *ReadStart;
do{
if( mad->Stream.buffer==NULL || mad->Stream.error==MAD_ERROR_BUFLEN ){
if ( mad->Stream.next_frame != NULL ){
Remaining = mad->Stream.bufend - mad->Stream.next_frame;
memmove( mad->input_buf, mad->Stream.next_frame, Remaining);
ReadStart = mad->input_buf + Remaining;
ReadSize = INPUT_BUFFER_SIZE - Remaining;
}
else{
ReadSize = INPUT_BUFFER_SIZE;
ReadStart = mad->input_buf;
Remaining = 0;
}
ReadSize = SDL_RWread( mad->src, ReadStart, 1, ReadSize );
if ( ReadSize <= 0 ) break; // end of stream
mad_stream_buffer( &mad->Stream, mad->input_buf, ReadSize + Remaining );
mad->Stream.error = MAD_ERROR_NONE;
}
if ( mad_frame_decode( &mad->Frame,&mad->Stream ) ){
if ( MAD_RECOVERABLE( mad->Stream.error ) ||
mad->Stream.error == MAD_ERROR_BUFLEN ){
continue;
}
else{
fprintf( stderr, "unrecoverable frame level error (%s).\n",
mad_stream_errorstr(&mad->Stream) );
return 0; // error
}
}
#if defined(PDA) && !defined(PSP)
if ( mad->Frame.header.samplerate == 44100 )
mad->Frame.options |= MAD_OPTION_HALFSAMPLERATE;
#endif
mad_synth_frame( &mad->Synth, &mad->Frame );
char *ptr = (char*)mad->output_buf + mad->output_buf_index;
for ( int i=0 ; i<mad->Synth.pcm.length ; i++ ){
unsigned short Sample;
/* Left channel */
Sample=MadFixedToUshort( mad->Synth.pcm.samples[0][i] );
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
*(ptr++) = Sample & 0xff;
*(ptr++) = Sample >> 8;
#else
*(ptr++) = Sample >> 8;
*(ptr++) = Sample & 0xff;
#endif
/* Right channel, if exist. */
if ( MAD_NCHANNELS(&mad->Frame.header)==2 )
Sample=MadFixedToUshort( mad->Synth.pcm.samples[1][i] );
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
*(ptr++) = Sample & 0xff;
*(ptr++) = Sample >> 8;
#else
*(ptr++) = Sample >> 8;
*(ptr++) = Sample&0xff;
#endif
}
mad->output_buf_index += mad->Synth.pcm.length * 4;
}
while( mad->output_buf_index < len );
if ( ReadSize <= 0 ) return 0; // end of stream
if ( mad->output_buf_index > len ){
SDL_MixAudio( stream, mad->output_buf, len, mad->volume );
memmove( mad->output_buf, mad->output_buf + len, mad->output_buf_index - len );
mad->output_buf_index -= len;
}
else{
SDL_MixAudio( stream, mad->output_buf, mad->output_buf_index, mad->volume );
len = mad->output_buf_index;
mad->output_buf_index = 0;
}
return len;
}
void MAD_WRAPPER_play( MAD_WRAPPER *mad )
{
mad->is_playing = true;
}
void MAD_WRAPPER_stop( MAD_WRAPPER *mad )
{
mad->is_playing = false;
}
void MAD_WRAPPER_delete( MAD_WRAPPER *mad )
{
mad_synth_finish( &mad->Synth );
mad_frame_finish( &mad->Frame );
mad_stream_finish( &mad->Stream );
delete[] mad->input_buf;
delete[] mad->output_buf;
SDL_FreeRW( mad->src );
delete mad;
}
void MAD_WRAPPER_setvolume( MAD_WRAPPER *mad, int volume )
{
if ( (volume >= 0) && (volume <= 100) ) {
mad->volume = (volume*SDL_MIX_MAXVOLUME) / 100;
}
}
const char* MAD_WRAPPER_error( MAD_WRAPPER *mad )
{
if ( mad ) return NULL;
return "Mad open error";
}
#ifdef DEBUG_MAD
void mp3callback( void *userdata, Uint8 *stream, int len )
{
if ( MAD_WRAPPER_playAudio( userdata, stream, len ) == 0 ){
printf("end of file\n");
exit(0);
}
}
int main(void)
{
if ( SDL_Init( SDL_INIT_TIMER | SDL_INIT_AUDIO ) < 0 ){
fprintf(stderr,
"Couldn't initialize SDL: %s\n", SDL_GetError());
exit(1);
}
SDL_AudioSpec audio_format;
MAD_WRAPPER *mad = MAD_WRAPPER_new( "travel.mp3", NULL, 0 );
MAD_WRAPPER_play( mad );
Mix_HookMusic( mp3callback, mad );
if ( Mix_OpenAudio( 44100, MIX_DEFAULT_FORMAT, MIX_DEFAULT_CHANNELS, DEFAULT_AUDIOBUF ) < 0 ){
fprintf(stderr, "Couldn't open audio device!\n"
" reason: [%s].\n", SDL_GetError());
exit(-1);
}
else{
int freq;
Uint16 format;
int channels;
Mix_QuerySpec( &freq, &format, &channels);
printf("Audio: %d Hz %d bit %s\n", freq,
(format&0xFF),
(channels > 1) ? "stereo" : "mono");
audio_format.format = format;
audio_format.freq = freq;
audio_format.channels = channels;
}
getchar();
MAD_WRAPPER_stop( mad );
MAD_WRAPPER_delete( mad );
}
#endif