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More patches from Frank.
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@icculus
icculus committed Jun 21, 2002
1 parent 1f7f425 commit 1b3231c
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Showing 3 changed files with 110 additions and 85 deletions.
97 changes: 48 additions & 49 deletions alt_audio_convert.c
View file
Expand Up @@ -26,7 +26,6 @@
*/

#include "alt_audio_convert.h"
#include <stdlib.h>
#include <math.h>

/* just to make sure this is defined... */
Expand All @@ -35,8 +34,8 @@
#define min(x, y) ( ((x) < (y)) ? (x) : (y) )
#endif

#ifndef max
#define max(x, y) ( ((x) > (y)) ? (x) : (y) )
#ifndef abs
#define abs(x) ( ((x) > (0)) ? (x) : -(x) )
#endif


Expand All @@ -49,17 +48,6 @@
#define IS_SYSENDIAN(x) ((~AUDIO_U16SYS ^ (x).format) & 0x1000)


/*-------------------------------------------------------------------------*/
/* this filter (Kaiser-window beta=6.8) gives a decent -80dB attentuation */
static const int filter[_fsize / 2] =
{
0, 20798, 0, -6764, 0, 3863, 0, -2560,
0, 1800, 0, -1295, 0, 936, 0, -671,
0, 474, 0, -326, 0, 217, 0, -138,
0, 83, 0, -46, 0, 23, 0, -9
};


/*-------------------------------------------------------------------------*/
/* the purpose of the RateConverterBuffer is to provide a continous storage
for head and tail of the (sample)-buffer. This allows a simple and
Expand Down Expand Up @@ -87,15 +75,15 @@ static const int filter[_fsize / 2] =
incremented or decremented depending on down or up conversion and the
first two input value are taken into account. This procedure repeats
until the filter has processed all zeroes. The distance of the pointer
movement is stored in flength.
movement is stored in flength, always positive.
Further a pointer cinp to the sample buffer itself is stored. The pointer
to the sample buffer is shifted too, so that on the first use of this
pointer the filter is complete in the sample buffer. The pointer moves
over the sample buffer until it reaches the other end. The distance of
the movement is stored in clength.
Finally the decay of the filter is done by linp, llength like finp,
Finally the decay of the filter is done by linp and llength like finp,
flength, but in reverse order.
buffer denotes the start or the end of the output buffer, depending
Expand All @@ -106,7 +94,7 @@ static const int filter[_fsize / 2] =

typedef struct
{
Sint16 inbuffer[6*_fsize];
Sint16 inbuffer[24*_fsize];
Sint16 *finp, *cinp, *linp;
Sint16 *buffer;
int flength, clength, llength;
Expand Down Expand Up @@ -361,51 +349,64 @@ static int minus5dB( AdapterC Data, int length )
}

/*-------------------------------------------------------------------------*/
enum RateConverterType { varRate = 0, hlfRate = 1, dblRate = 2 };
static void initRateConverterBuffer( RateConverterBuffer *rcb,
AdapterC* Data, int length, int rel_size )
AdapterC* Data, int length, RateConverterType r, int rel_size )
{
int size, slength;
int den, num;
int size, dir;
int den[] = { 0, 1, 2};
int num[] = { 0, 2, 1};
int i;

den = Data->filter->denominator;
num = Data->filter->numerator;
size = _fsize * rel_size;
den[0] = Data->filter->denominator;
num[0] = Data->filter->numerator;

size = 2 * _fsize * abs(rel_size);
dir = rel_size > 0 ? 1 : 0;
length >>= 1;
slength = rel_size > 0 ? length : -length;

rcb->buffer = (Sint16*)( Data->buffer );

if( Data->mode & SDL_AI_Loop )
{
// !!!FIXME: modulo length, take scale into account
// !!!FIXME: modulo length, take scale into account,
// check against the 'else' part
for( i = 0; i < size; i++ )
{
rcb->inbuffer[i] = rcb->buffer[length-size+i];
rcb->inbuffer[i+size] = rcb->buffer[i];
}
rcb->finp = rcb->linp = rcb->inbuffer + size;
if( size < 0 )
rcb->buffer += num * ( length + 2 * size ) / den;
rcb->buffer += num[r] * ( length + 2 * size ) / den[r];
}
else
{
for( i = 0; i < size; i++ )
{
int j;
j = length-size+i;
rcb->inbuffer[i] = j < 0 ? 0 : rcb->buffer[j];
int k;
k = length-size+i;
rcb->inbuffer[i] = k < 0 ? 0 : rcb->buffer[k];
rcb->inbuffer[i+size] = 0;
rcb->inbuffer[i+2*size] = i < length ? rcb->buffer[i] : 0;
}
// !!!FIXME: take lenght < size into account
rcb->finp = rcb->inbuffer + abs( 3*size/2 ) + size/2;
rcb->linp = rcb->inbuffer + abs( 3*size/2 ) - size/2;
rcb->flength = rcb->llength = 2*size;
rcb->clength = slength - 2*size;
rcb->flength = rcb->llength = size;
rcb->clength = length - size;

if( size < 0 )
rcb->buffer += num * ( length + 2 * size ) / den;
if( dir )
{
rcb->finp = rcb->inbuffer + 5*size/2;
rcb->cinp = rcb->buffer + length - size/2;
rcb->linp = rcb->inbuffer + 3*size/2;
rcb->buffer += den[r] * ( length + size ) / num[r];
}
else
{
rcb->finp = rcb->inbuffer + size/2;
rcb->cinp = rcb->buffer + size/2;
rcb->linp = rcb->inbuffer + 3*size/2;
}
}
}

Expand Down Expand Up @@ -436,14 +437,14 @@ static int doRateConversion( RateConverterBuffer* rcb,
static int doubleRateMono( AdapterC Data, int length )
{
RateConverterBuffer rcb;
initRateConverterBuffer( &rcb, &Data, length, 1 );
initRateConverterBuffer( &rcb, &Data, length, dblRate, 1 );
return doRateConversion( &rcb, doubleRate1, NULL );
}

static int doubleRateStereo( AdapterC Data, int length )
{
RateConverterBuffer rcb;
initRateConverterBuffer( &rcb, &Data, length, 2 );
initRateConverterBuffer( &rcb, &Data, length, dblRate, 2 );
doRateConversion( &rcb, doubleRate2, NULL );
nextRateConverterBuffer( &rcb );
return 2 + doRateConversion( &rcb, doubleRate2, NULL );
Expand All @@ -453,14 +454,14 @@ static int doubleRateStereo( AdapterC Data, int length )
static int halfRateMono( AdapterC Data, int length )
{
RateConverterBuffer rcb;
initRateConverterBuffer( &rcb, &Data, length, -1 );
initRateConverterBuffer( &rcb, &Data, length, hlfRate, -1 );
return doRateConversion( &rcb, halfRate1, NULL );
}

static int halfRateStereo( AdapterC Data, int length )
{
RateConverterBuffer rcb;
initRateConverterBuffer( &rcb, &Data, length, -2 );
initRateConverterBuffer( &rcb, &Data, length, hlfRate, -2 );
doRateConversion( &rcb, halfRate2, NULL );
nextRateConverterBuffer( &rcb );
return 2 + doRateConversion( &rcb, halfRate2, NULL );
Expand All @@ -470,14 +471,14 @@ static int halfRateStereo( AdapterC Data, int length )
static int increaseRateMono( AdapterC Data, int length )
{
RateConverterBuffer rcb;
initRateConverterBuffer( &rcb, &Data, length, 2 );
initRateConverterBuffer( &rcb, &Data, length, varRate, 2 );
return doRateConversion( &rcb, increaseRate1, Data.filter );
}

static int increaseRateStereo( AdapterC Data, int length )
{
RateConverterBuffer rcb;
initRateConverterBuffer( &rcb, &Data, length, 4 );
initRateConverterBuffer( &rcb, &Data, length, varRate, 4 );
doRateConversion( &rcb, increaseRate2, Data.filter );
nextRateConverterBuffer( &rcb );
return 2 + doRateConversion( &rcb, increaseRate2, Data.filter );
Expand All @@ -487,14 +488,14 @@ static int increaseRateStereo( AdapterC Data, int length )
static int decreaseRateMono( AdapterC Data, int length )
{
RateConverterBuffer rcb;
initRateConverterBuffer( &rcb, &Data, length, -2 );
initRateConverterBuffer( &rcb, &Data, length, varRate, -2 );
return doRateConversion( &rcb, decreaseRate1, Data.filter );
}

static int decreaseRateStereo( AdapterC Data, int length )
{
RateConverterBuffer rcb;
initRateConverterBuffer( &rcb, &Data, length, -4 );
initRateConverterBuffer( &rcb, &Data, length, varRate, -4 );
doRateConversion( &rcb, decreaseRate2, Data.filter );
nextRateConverterBuffer( &rcb );
return doRateConversion( &rcb, decreaseRate2, Data.filter );
Expand Down Expand Up @@ -535,7 +536,7 @@ static Fraction findFraction( float Value )
float RelErr, BestErr = 0;
if( Value < 31/64. || Value > 64/31. ) return Result;

for( n = 0; n < sizeof(frac); num=frac[n++] )
for( n = 0; n < SDL_TABLESIZE(frac); num=frac[n++] )
{
if( num < 0 ) den++;
RelErr = Value * num / den;
Expand Down Expand Up @@ -609,10 +610,10 @@ static void setupVarFilter( VarFilter* filter,
if( phase >= n )
{
phase -= d;
filter->incr[i] = Direction.incr;
filter->incr[i] = abs(Direction.incr);
}
else
filter->incr[i] = 1+Direction.incr;
filter->incr[i] = abs(1+Direction.incr);

calculateVarFilter( filter->c[i], Ratio, phase/(float)n,
Direction.scale );
Expand Down Expand Up @@ -899,13 +900,11 @@ static void show_AudioCVT( Sound_AudioCVT *Data )
AdapterDesc(decreaseRateStereo),
{ NULL, "----------NULL-----------" }
};
const int AdapterDescMax = sizeof(AdapterDescription)
/ sizeof(*AdapterDescription);

fprintf( stderr, "\nAdapter List: \n" );
for( i = 0; i < 32; i++ )
{
for( j = 0; j < AdapterDescMax; j++ )
for( j = 0; j < SDL_TABLESIZE(AdapterDescription); j++ )
{
if( Data->adapter[i] == AdapterDescription[j].adapter )
{
Expand Down
10 changes: 5 additions & 5 deletions alt_audio_convert.h
View file
Expand Up @@ -25,16 +25,16 @@
* (This code blatantly abducted for SDL_sound. Thanks, Frank! --ryan.)
*/

#ifndef _INCLUDE_ALT_AUDIO_CONVERT_H_
#define _INCLUDE_ALT_AUDIO_CONVERT_H_
#ifndef _INCLUDE_AUDIO_CONVERT_H_
#define _INCLUDE_AUDIO_CONVERT_H_

#include "SDL_audio.h"
#define Sound_AI_Loop 0x2
#define _fsize 64
#define _fsize 32


typedef struct{
Sint16 c[16][2*_fsize];
Sint16 c[16][4*_fsize];
char incr[16];
int denominator;
int numerator;
Expand Down Expand Up @@ -74,5 +74,5 @@ extern DECLSPEC int Sound_BuildAudioCVT( Sound_AudioCVT *Data,
Uint16 src_format, Uint8 src_channels, int src_rate,
Uint16 dst_format, Uint8 dst_channels, int dst_rate );

#endif /* _INCLUDE_ALT_AUDIO_CONVERT_H_ */
#endif /* _INCLUDE_AUDIO_CONVERT_H_ */

Expand Down

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