ref: 2515cb2de68b10eff93b876159dcbf180474f146
dir: /src/ima_rw.c/
/*
ima_rw.c -- codex utilities for WAV_FORMAT_IMA_ADPCM
Copyright (C) 1999 Stanley J. Brooks <stabro@megsinet.net>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <sys/types.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "st_i.h"
#include "ima_rw.h"
/*
*
* Lookup tables for IMA ADPCM format
*
*/
#define ISSTMAX 88
static const int imaStepSizeTable[ISSTMAX + 1] = {
7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 21, 23, 25, 28, 31, 34,
37, 41, 45, 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143,
157, 173, 190, 209, 230, 253, 279, 307, 337, 371, 408, 449, 494,
544, 598, 658, 724, 796, 876, 963, 1060, 1166, 1282, 1411, 1552,
1707, 1878, 2066, 2272, 2499, 2749, 3024, 3327, 3660, 4026,
4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493, 10442,
11487, 12635, 13899, 15289, 16818, 18500, 20350, 22385, 24623,
27086, 29794, 32767
};
#define imaStateAdjust(c) (((c)<4)? -1:(2*(c)-6))
/* +0 - +3, decrease step size */
/* +4 - +7, increase step size */
/* -0 - -3, decrease step size */
/* -4 - -7, increase step size */
static unsigned char imaStateAdjustTable[ISSTMAX+1][8];
void initImaTable(void)
{
int i,j,k;
for (i=0; i<=ISSTMAX; i++) {
for (j=0; j<8; j++) {
k = i + imaStateAdjust(j);
if (k<0) k=0;
else if (k>ISSTMAX) k=ISSTMAX;
imaStateAdjustTable[i][j] = k;
}
}
}
static void ImaExpandS(
int ch, /* channel number to decode, REQUIRE 0 <= ch < chans */
int chans, /* total channels */
const unsigned char *ibuff,/* input buffer[blockAlign] */
SAMPL *obuff, /* obuff[n] will be output samples */
int n, /* samples to decode PER channel, REQUIRE n % 8 == 1 */
int o_inc /* index difference between successive output samples */
)
{
const unsigned char *ip;
int i_inc;
SAMPL *op;
int i, val, state;
ip = ibuff + 4*ch; /* input pointer to 4-byte block state-initializer */
i_inc = 4*(chans-1); /* amount by which to incr ip after each 4-byte read */
val = (short)(ip[0] + (ip[1]<<8)); /* need cast for sign-extend */
state = ip[2];
if (state > ISSTMAX) {
st_warn("IMA_ADPCM block ch%d initial-state (%d) out of range", ch, state);
state = 0;
}
/* specs say to ignore ip[3] , but write it as 0 */
ip += 4+i_inc;
op = obuff;
*op = val; /* 1st output sample for this channel */
op += o_inc;
for (i = 1; i < n; i++) {
int step,dp,c,cm;
if (i&1) { /* 1st of pair */
cm = *ip & 0x0f;
} else {
cm = (*ip++)>>4;
if ((i&7) == 0) /* ends the 8-sample input block for this channel */
ip += i_inc; /* skip ip for next group */
}
step = imaStepSizeTable[state];
/* Update the state for the next sample */
c = cm & 0x07;
state = imaStateAdjustTable[state][c];
dp = 0;
if (c & 4) dp += step;
step = step >> 1;
if (c & 2) dp += step;
step = step >> 1;
if (c & 1) dp += step;
step = step >> 1;
dp += step;
if (c != cm) {
val -= dp;
if (val<-0x8000) val = -0x8000;
} else {
val += dp;
if (val>0x7fff) val = 0x7fff;
}
*op = val;
op += o_inc;
}
return;
}
/* ImaBlockExpandI() outputs interleaved samples into one output buffer */
void ImaBlockExpandI(
int chans, /* total channels */
const unsigned char *ibuff,/* input buffer[blockAlign] */
SAMPL *obuff, /* output samples, n*chans */
int n /* samples to decode PER channel, REQUIRE n % 8 == 1 */
)
{
int ch;
for (ch=0; ch<chans; ch++)
ImaExpandS(ch, chans, ibuff, obuff+ch, n, chans);
}
/* ImaBlockExpandM() outputs non-interleaved samples into chan separate output buffers */
void ImaBlockExpandM(
int chans, /* total channels */
const unsigned char *ibuff,/* input buffer[blockAlign] */
SAMPL **obuffs, /* chan output sample buffers, each takes n samples */
int n /* samples to decode PER channel, REQUIRE n % 8 == 1 */
)
{
int ch;
for (ch=0; ch<chans; ch++)
ImaExpandS(ch, chans, ibuff, obuffs[ch], n, 1);
}
static int ImaMashS(
int ch, /* channel number to encode, REQUIRE 0 <= ch < chans */
int chans, /* total channels */
SAMPL v0, /* value to use as starting prediction0 */
const SAMPL *ibuff, /* ibuff[] is interleaved input samples */
int n, /* samples to encode PER channel, REQUIRE n % 8 == 1 */
int *st, /* input/output state, REQUIRE 0 <= *st <= ISSTMAX */
unsigned char *obuff /* output buffer[blockAlign], or NULL for no output */
)
{
const SAMPL *ip, *itop;
unsigned char *op;
int o_inc = 0; /* set 0 only to shut up gcc's 'might be uninitialized' */
int i, val;
int state;
double d2; /* long long is okay also, speed abt the same */
ip = ibuff + ch; /* point ip to 1st input sample for this channel */
itop = ibuff + n*chans;
val = *ip - v0; ip += chans;/* 1st input sample for this channel */
d2 = val*val;/* d2 will be sum of squares of errors, given input v0 and *st */
val = v0;
op = obuff; /* output pointer (or NULL) */
if (op) { /* NULL means don't output, just compute the rms error */
op += 4*ch; /* where to put this channel's 4-byte block state-initializer */
o_inc = 4*(chans-1); /* amount by which to incr op after each 4-byte written */
*op++ = val; *op++ = val>>8;
*op++ = *st; *op++ = 0; /* they could have put a mid-block state-correction here */
op += o_inc; /* _sigh_ NEVER waste a byte. It's a rule! */
}
state = *st;
for (i = 0; ip < itop; ip+=chans) {
int step,d,dp,c;
d = *ip - val; /* difference between last prediction and current sample */
step = imaStepSizeTable[state];
c = (abs(d)<<2)/step;
if (c > 7) c = 7;
/* Update the state for the next sample */
state = imaStateAdjustTable[state][c];
if (op) { /* if we want output, put it in proper place */
int cm = c;
if (d<0) cm |= 8;
if (i&1) { /* odd numbered output */
*op++ |= (cm<<4);
if (i == 7) /* ends the 8-sample output block for this channel */
op += o_inc; /* skip op for next group */
} else {
*op = cm;
}
i = (i+1) & 0x07;
}
dp = 0;
if (c & 4) dp += step;
step = step >> 1;
if (c & 2) dp += step;
step = step >> 1;
if (c & 1) dp += step;
step = step >> 1;
dp += step;
if (d<0) {
val -= dp;
if (val<-0x8000) val = -0x8000;
} else {
val += dp;
if (val>0x7fff) val = 0x7fff;
}
{
int x = *ip - val;
d2 += x*x;
}
}
d2 /= n; /* be sure it's non-negative */
*st = state;
return (int) sqrt(d2);
}
/* mash one channel... if you want to use opt>0, 9 is a reasonable value */
inline static void ImaMashChannel(
int ch, /* channel number to encode, REQUIRE 0 <= ch < chans */
int chans, /* total channels */
const SAMPL *ip, /* ip[] is interleaved input samples */
int n, /* samples to encode PER channel, REQUIRE n % 8 == 1 */
int *st, /* input/output state, REQUIRE 0 <= *st <= ISSTMAX */
unsigned char *obuff, /* output buffer[blockAlign] */
int opt /* non-zero allows some cpu-intensive code to improve output */
)
{
int snext,d;
int s0,d0;
int s32,d32;
s32 = s0 = *st;
if (opt>0) {
int low,hi,w;
int low0,hi0;
snext = s0;
d32 = d0 = ImaMashS(ch, chans, ip[0], ip,n,&snext, NULL);
w = 0;
low=hi=s0;
low0 = low-opt; if (low0<0) low0=0;
hi0 = hi+opt; if (hi0>ISSTMAX) hi0=ISSTMAX;
while (low>low0 || hi<hi0) {
if (!w && low>low0) {
int d;
snext = --low;
d = ImaMashS(ch, chans, ip[0], ip,n,&snext, NULL);
if (d<d0) {
d0=d; s0=low;
low0 = low-opt; if (low0<0) low0=0;
hi0 = low+opt; if (hi0>ISSTMAX) hi0=ISSTMAX;
}
}
if (w && hi<hi0) {
int d;
snext = ++hi;
d = ImaMashS(ch, chans, ip[0], ip,n,&snext, NULL);
if (d<d0) {
d0=d; s0=hi;
low0 = hi-opt; if (low0<0) low0=0;
hi0 = hi+opt; if (hi0>ISSTMAX) hi0=ISSTMAX;
}
}
w=1-w;
}
*st = s0;
}
d = ImaMashS(ch, chans, ip[0], ip,n,st, obuff);
}
/* mash one block. if you want to use opt>0, 9 is a reasonable value */
void ImaBlockMashI(
int chans, /* total channels */
const SAMPL *ip, /* ip[] is interleaved input samples */
int n, /* samples to encode PER channel, REQUIRE n % 8 == 1 */
int *st, /* input/output state, REQUIRE 0 <= *st <= ISSTMAX */
unsigned char *obuff, /* output buffer[blockAlign] */
int opt /* non-zero allows some cpu-intensive code to improve output */
)
{
int ch;
for (ch=0; ch<chans; ch++)
ImaMashChannel(ch, chans, ip, n, st+ch, obuff, opt);
}
/*
* ImaSamplesIn(dataLen, chans, blockAlign, samplesPerBlock)
* returns the number of samples/channel which would go
* in the dataLen, given the other parameters ...
* if input samplesPerBlock is 0, then returns the max
* samplesPerBlock which would go into a block of size blockAlign
* Yes, it is confusing.
*/
st_size_t ImaSamplesIn(
st_size_t dataLen,
unsigned short chans,
unsigned short blockAlign,
unsigned short samplesPerBlock
)
{
st_size_t m, n;
if (samplesPerBlock) {
n = (dataLen / blockAlign) * samplesPerBlock;
m = (dataLen % blockAlign);
} else {
n = 0;
m = blockAlign;
}
if (m >= (st_size_t)4*chans) {
m -= 4*chans; /* number of bytes beyond block-header */
m /= 4*chans; /* number of 4-byte blocks/channel beyond header */
m = 8*m + 1; /* samples/chan beyond header + 1 in header */
if (samplesPerBlock && m > samplesPerBlock) m = samplesPerBlock;
n += m;
}
return n;
/*wSamplesPerBlock = ((wBlockAlign - 4*wChannels)/(4*wChannels))*8 + 1;*/
}
/*
* st_size_t ImaBytesPerBlock(chans, samplesPerBlock)
* return minimum blocksize which would be required
* to encode number of chans with given samplesPerBlock
*/
st_size_t ImaBytesPerBlock(
unsigned short chans,
unsigned short samplesPerBlock
)
{
st_size_t n;
/* per channel, ima has blocks of len 4, the 1st has 1st sample, the others
* up to 8 samples per block,
* so number of later blocks is (nsamp-1 + 7)/8, total blocks/chan is
* (nsamp-1+7)/8 + 1 = (nsamp+14)/8
*/
n = ((st_size_t)samplesPerBlock + 14)/8 * 4 * chans;
return n;
}