vencode.c
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#include "vadpcm.h"
int
vencodeframe(FILE *ofile, short *inBuffer, int *state, int ***coefTable, int order, int npredictors, int nsam)
{
short
ix[FRAMESIZE];
int
prediction[FRAMESIZE],
inVector[FRAMESIZE],
saveState[FRAMESIZE],
optimalp,
scale,
llevel,
ulevel,
i,
j,
k,
ie[FRAMESIZE],
nIter,
max,
cV,
maxClip;
unsigned char
header,
c;
float
e[FRAMESIZE],
se,
min;
/*
* Clear input for nsam less than FRAMESIZE
*/
for (i=nsam; i<FRAMESIZE; i++)
inBuffer[i] = 0;
/*
* Maximum and minimum allowable levels
*/
llevel = - (short) (1L<<(SAMPLEBITS-1));
ulevel = -llevel - 1;
/*
* Find the prediction error for each possible predictor. Uses the
* vector method.
*/
min = 1e30; optimalp = 0;
for (k=0; k<npredictors; k++){
/*
* Set up previous frame outputs - use quantized outputs
*/
for (i=0; i<order; i++)
inVector[i] = state[FRAMESIZE-order+i];
for (i=0; i<VECTORSIZE; i++){
prediction[i] = inner_product(order+i, coefTable[k][i], inVector);
inVector[i+order] = htons(inBuffer[i]) - prediction[i];
e[i] = (float) inVector[i+order];
}
/*
* Set up previous vector outputs, for next lot of VECTORSIZE
*/
for (i=0; i<order; i++)
inVector[i] = prediction[VECTORSIZE-order+i]+inVector[VECTORSIZE+i];
for (i=0; i<VECTORSIZE; i++){
prediction[i+VECTORSIZE] = inner_product(order+i, coefTable[k][i], inVector);
inVector[i+order] = htons(inBuffer[VECTORSIZE+i]) - prediction[i+VECTORSIZE];
e[i+VECTORSIZE] = (float) inVector[i+order];
}
/*
* Now find the error measure for this frame and check
* against the current best.
*/
se = 0;
for (j=0; j<FRAMESIZE; j++)
se += e[j]*e[j];
if (se<min){
min=se;
optimalp = k;
}
}
/*
* Re-calculate final prediction error using optimal predictor
*/
for (i=0; i<order; i++)
inVector[i] = state[FRAMESIZE-order+i];
for (i=0; i<VECTORSIZE; i++){
prediction[i] = inner_product(order+i, coefTable[optimalp][i], inVector);
inVector[i+order] = htons(inBuffer[i]) - prediction[i];
e[i] = (float) inVector[i+order];
}
for (i=0; i<order; i++)
inVector[i] = prediction[VECTORSIZE-order+i]+inVector[VECTORSIZE+i];
for (i=0; i<VECTORSIZE; i++){
prediction[i+VECTORSIZE] = inner_product(order+i, coefTable[optimalp][i], inVector);
inVector[i+order] = htons(inBuffer[VECTORSIZE+i]) - prediction[i+VECTORSIZE];
e[i+VECTORSIZE] = (float) inVector[i+order];
}
/*
* Find range value
*/
clamp(FRAMESIZE, e, ie, 16);
max = 0;
for (i=0; i<FRAMESIZE; i++)
if (fabs(ie[i])>fabs(max))
max = ie[i];
for (scale=0; scale<=MAXSCALE; scale++){
if ((max<=ulevel) && (max>=llevel))
break;
max /= 2;
}
/*
* Final prediction error with a quantizer in the loop
*/
for (i=0; i<FRAMESIZE; i++)
saveState[i] = state[i];
scale--;
nIter = 0;
do {
nIter++;
maxClip = 0;
scale++;
if (scale > MAXSCALE)
scale = MAXSCALE;
for (i=0; i<order; i++)
inVector[i] = saveState[FRAMESIZE-order+i];
for (i=0; i<VECTORSIZE; i++){
prediction[i] = inner_product(order+i, coefTable[optimalp][i], inVector);
se = (float) htons(inBuffer[i]) - prediction[i];
ix[i] = qsample(se, 1<<scale);
cV = (short) clip((int) ix[i], llevel, ulevel) - ix[i];
if (abs(cV) > maxClip)
maxClip = abs(cV);
ix[i] += cV;
inVector[i+order] = ix[i]*(1<<scale);
/*
* Decoder output
*/
state[i] = prediction[i] + inVector[i+order];
}
for (i=0; i<order; i++)
inVector[i] = state[VECTORSIZE-order+i];
for (i=0; i<VECTORSIZE; i++){
prediction[i+VECTORSIZE] = inner_product(order+i, coefTable[optimalp][i], inVector);
se = (float) htons(inBuffer[VECTORSIZE+i]) - prediction[VECTORSIZE+i];
ix[VECTORSIZE+i] = qsample(se, 1<<scale);
cV = (short) clip((int) ix[i+VECTORSIZE], llevel, ulevel) - ix[i+VECTORSIZE];
if (abs(cV) > maxClip)
maxClip = abs(cV);
ix[i+VECTORSIZE] += cV;
inVector[i+order] = ix[VECTORSIZE+i]*(1<<scale);
state[VECTORSIZE+i] = prediction[i+VECTORSIZE] + inVector[i+order];
}
}
while ((maxClip > MAXCLIP) && (nIter < MAXITER));
/*
* Write frame header and bitstream
*/
header = (scale<<4) | ((optimalp) & 0xf);
fwrite(&header, 1, 1, ofile);
for (i=0; i<FRAMESIZE; i+=2){
c = (ix[i]<<4) | (ix[i+1] & 0xf);
fwrite(&c, 1, 1, ofile);
}
}