private int decodeFrame(int frameStart) {
int nbFrames;
if (ctx.header.errorProtection != 0) {
br.skip(16);
}
switch (ctx.header.layer) {
case 1:
nbFrames = decodeLayer1();
break;
case 2:
nbFrames = decodeLayer2();
break;
case 3:
default:
nbFrames = decodeLayer3(frameStart);
break;
}
if (nbFrames < 0) {
return nbFrames;
}
// get output buffer
if (ctx.samples == null) {
ctx.samples = new float[ctx.header.nbChannels][ctx.header.maxSamples];
}
// apply the synthesis filter
for (int ch = 0; ch < ctx.header.nbChannels; ch++) {
int sampleStride = 1;
int samplesPtr = 0;
for (int i = 0; i < nbFrames; i++) {
Mp3Dsp.synthFilter(
ctx, ch, ctx.samples[ch], samplesPtr, sampleStride, ctx.sbSamples[ch], i * SBLIMIT);
samplesPtr += 32 * sampleStride;
}
}
return nbFrames * 32 * 4 * ctx.header.nbChannels;
}
private void initStatic() {
if (initializedTables) {
return;
}
// scale factors table for layer 1/2
for (int i = 0; i < 64; i++) {
// 1.0 (i = 3) is normalized to 2 ^ FRAC_BITS
int shift = i / 3;
int mod = i % 3;
scale_factor_modshift[i] = mod | (shift << 2);
}
// scale factor multiply for layer 1
for (int i = 0; i < 15; i++) {
int n = i + 2;
int norm = (int) (((1L << n) * FRAC_ONE) / ((1 << n) - 1));
scale_factor_mult[i][0] = (int) (norm * 1.0f * 2.0f);
scale_factor_mult[i][1] = (int) (norm * 0.7937005259f * 2.0f);
scale_factor_mult[i][2] = (int) (norm * 0.6299605249f * 2.0f);
}
Mp3Dsp.synthInit(Mp3Dsp.mpa_synth_window);
// Huffman decode tables
for (int i = 1; i < 16; i++) {
HuffTable h = Mp3Data.mpa_huff_tables[i];
int[] tmpBits = new int[512];
int[] tmpCodes = new int[512];
int xsize = h.xsize;
int j = 0;
for (int x = 0; x < xsize; x++) {
for (int y = 0; y < xsize; y++) {
tmpBits[(x << 5) | y | ((x != 0 && y != 0) ? 16 : 0)] = h.bits[j];
tmpCodes[(x << 5) | y | ((x != 0 && y != 0) ? 16 : 0)] = h.codes[j++];
}
}
huff_vlc[i] = new VLC();
huff_vlc[i].initVLCSparse(7, 512, tmpBits, tmpCodes, null);
}
for (int i = 0; i < 2; i++) {
huff_quad_vlc[i] = new VLC();
huff_quad_vlc[i].initVLCSparse(i == 0 ? 7 : 4, 16, mpa_quad_bits[i], mpa_quad_codes[i], null);
}
for (int i = 0; i < 9; i++) {
int k = 0;
for (int j = 0; j < 22; j++) {
band_index_long[i][j] = k;
k += band_size_long[i][j];
}
band_index_long[i][22] = k;
}
Mp3Data.tableinit();
Mp3Dsp.initMpadspTabs();
for (int i = 0; i < 4; i++) {
if (mp3_quant_bits[i] < 0) {
for (int j = 0; j < (1 << (-mp3_quant_bits[i] + 1)); j++) {
int val = j;
int steps = Mp3Data.mp3_quant_steps[i];
int val1 = val % steps;
val /= steps;
int val2 = val % steps;
int val3 = val / steps;
division_tabs[i][j] = val1 + (val2 << 4) + (val3 << 8);
}
}
}
for (int i = 0; i < 7; i++) {
float v;
if (i != 6) {
float f = (float) Math.tan(i * Math.PI / 12.0);
v = f / (1f + f);
} else {
v = 1f;
}
is_table[0][i] = v;
is_table[1][6 - i] = v;
}
// invalid values
for (int i = 7; i < 16; i++) {
is_table[0][i] = 0f;
is_table[1][i] = 0f;
}
for (int i = 0; i < 16; i++) {
for (int j = 0; j < 2; j++) {
int e = -(j + 1) * ((i + 1) >> 1);
double f = pow(2.0, e / 4.0);
int k = i & 1;
is_table_lsf[j][k ^ 1][i] = (float) f;
is_table_lsf[j][k][i] = 1f;
}
}
for (int i = 0; i < 8; i++) {
float ci = ci_table[i];
float cs = (float) (1.0 / Math.sqrt(1.0 + ci * ci));
float ca = cs * ci;
csa_table[i][0] = cs;
csa_table[i][1] = ca;
csa_table[i][2] = ca + cs;
csa_table[i][3] = ca - cs;
}
initializedTables = true;
}
private void computeImdct(Granule g, float[] sbSamples, int sbSamplesOffset, float[] mdctbuf) {
float out2[] = new float[12];
// find last non zero block
int ptr = 576;
int ptr1 = 2 * 18;
float[] p = g.sbHybrid;
while (ptr >= ptr1) {
ptr -= 6;
if (p[ptr] != 0f
|| p[ptr + 1] != 0f
|| p[ptr + 2] != 0f
|| p[ptr + 3] != 0f
|| p[ptr + 4] != 0f
|| p[ptr + 5] != 0f) {
break;
}
}
int sblimit = ptr / 18 + 1;
int mdctLongEnd;
if (g.blockType == 2) {
if (g.switchPoint != 0) {
mdctLongEnd = 2;
} else {
mdctLongEnd = 0;
}
} else {
mdctLongEnd = sblimit;
}
Mp3Dsp.imdct36Blocks(
sbSamples,
sbSamplesOffset,
mdctbuf,
0,
g.sbHybrid,
0,
mdctLongEnd,
g.switchPoint,
g.blockType);
int buf = 4 * 18 * (mdctLongEnd >> 2) + (mdctLongEnd & 3);
ptr = 18 * mdctLongEnd;
for (int j = mdctLongEnd; j < sblimit; j++) {
// select frequency inversion
float win[] = mdct_win[2 + (4 & -(j & 1))];
int outPtr = j;
for (int i = 0; i < 6; i++) {
sbSamples[outPtr] = mdctbuf[buf + 4 * i];
outPtr += SBLIMIT;
}
imdct12(out2, 0, g.sbHybrid, ptr + 0);
for (int i = 0; i < 6; i++) {
sbSamples[outPtr] = out2[i] * win[i] + mdctbuf[buf + 4 * (i + 6 * 1)];
mdctbuf[buf + 4 * (i + 6 * 2)] = out2[i + 6] * win[i + 6];
outPtr += SBLIMIT;
}
imdct12(out2, 0, g.sbHybrid, ptr + 1);
for (int i = 0; i < 6; i++) {
sbSamples[outPtr] = out2[i] * win[i] + mdctbuf[buf + 4 * (i + 6 * 2)];
mdctbuf[buf + 4 * (i + 6 * 0)] = out2[i + 6] * win[i + 6];
outPtr += SBLIMIT;
}
imdct12(out2, 0, g.sbHybrid, ptr + 2);
for (int i = 0; i < 6; i++) {
mdctbuf[buf + 4 * (i + 6 * 0)] = out2[i] * win[i] + mdctbuf[buf + 4 * (i + 6 * 0)];
mdctbuf[buf + 4 * (i + 6 * 1)] = out2[i + 6] * win[i + 6];
mdctbuf[buf + 4 * (i + 6 * 2)] = 0f;
}
ptr += 18;
buf += (j & 3) != 3 ? 1 : (4 * 18 - 3);
}
// zero bands
for (int j = sblimit; j < SBLIMIT; j++) {
// overlap
int outPtr = j;
for (int i = 0; i < 18; i++) {
sbSamples[outPtr] = mdctbuf[buf + 4 * i];
mdctbuf[buf + 4 * i] = 0f;
outPtr += SBLIMIT;
}
buf += (j & 3) != 3 ? 1 : (4 * 18 - 3);
}
}