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iac: generate codec tables as they are supposed to be

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Unlike its predecessor, Indeo Audio codec generates tables depending on
sampling rate. Previously decoder used pre-generated tables for 22050 Hz
which obviously doesn't work with other frequencies.

Many thanks to Maxim Poliakovsky for providing all needed information
for this.
This commit is contained in:
Kostya Shishkov 2012-06-08 19:34:46 +02:00
parent e1a3fa5d3a
commit cac4760bf4
2 changed files with 62 additions and 25 deletions
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68
libavcodec/imc.c
View File

@ -114,6 +114,62 @@ static const int vlc_offsets[17] = {
static VLC_TYPE vlc_tables[VLC_TABLES_SIZE][2];
static inline double freq2bark(double freq)
{
return 3.5 * atan((freq / 7500.0) * (freq / 7500.0)) + 13.0 * atan(freq * 0.00076);
}
static av_cold void iac_generate_tabs(IMCContext *q, int sampling_rate)
{
double freqmin[32], freqmid[32], freqmax[32];
double scale = sampling_rate / (256.0 * 2.0 * 2.0);
double nyquist_freq = sampling_rate * 0.5;
double freq, bark, prev_bark = 0, tf, tb;
int i, j;
for (i = 0; i < 32; i++) {
freq = (band_tab[i] + band_tab[i + 1] - 1) * scale;
bark = freq2bark(freq);
if (i > 0) {
tb = bark - prev_bark;
q->weights1[i - 1] = pow(10.0, -1.0 * tb);
q->weights2[i - 1] = pow(10.0, -2.7 * tb);
}
prev_bark = bark;
freqmid[i] = freq;
tf = freq;
while (tf < nyquist_freq) {
tf += 0.5;
tb = freq2bark(tf);
if (tb > bark + 0.5)
break;
}
freqmax[i] = tf;
tf = freq;
while (tf > 0.0) {
tf -= 0.5;
tb = freq2bark(tf);
if (tb <= bark - 0.5)
break;
}
freqmin[i] = tf;
}
for (i = 0; i < 32; i++) {
freq = freqmax[i];
for (j = 31; j > 0 && freq <= freqmid[j]; j--);
q->cyclTab[i] = j + 1;
freq = freqmin[i];
for (j = 0; j < 32 && freq >= freqmid[j]; j++);
q->cyclTab2[i] = j - 1;
}
}
static av_cold int imc_decode_init(AVCodecContext *avctx)
{
int i, j, ret;
@ -173,14 +229,14 @@ static av_cold int imc_decode_init(AVCodecContext *avctx)
}
q->one_div_log2 = 1 / log(2);
memcpy(q->cyclTab, cyclTab, sizeof(cyclTab));
memcpy(q->cyclTab2, cyclTab2, sizeof(cyclTab2));
if (avctx->codec_id == CODEC_ID_IAC) {
q->cyclTab[29] = 31;
q->cyclTab2[31] = 28;
memcpy(q->weights1, iac_weights1, sizeof(iac_weights1));
memcpy(q->weights2, iac_weights2, sizeof(iac_weights2));
}
if (avctx->codec_id == CODEC_ID_IAC) {
iac_generate_tabs(q, avctx->sample_rate);
} else {
memcpy(q->cyclTab, cyclTab, sizeof(cyclTab));
memcpy(q->cyclTab2, cyclTab2, sizeof(cyclTab2));
memcpy(q->weights1, imc_weights1, sizeof(imc_weights1));
memcpy(q->weights2, imc_weights2, sizeof(imc_weights2));
}

19
libavcodec/imcdata.h
View File

@ -44,25 +44,6 @@ static const int8_t cyclTab2[32] = {
12, 13, 14, 15, 16, 17, 17, 18, 19, 20, 21, 22,
23, 24, 25, 26, 27, 28, 29};
static const float iac_weights1[31] = {
0.0538585, 0.0576251, 0.0645592, 0.0494032, 0.0428915, 0.0592188,
0.0604145, 0.0673549, 0.0797351, 0.0972911, 0.119376, 0.144777,
0.17181, 0.198625, 0.242918, 0.262113, 0.278434, 0.310752,
0.319978, 0.328482, 0.354631, 0.380212, 0.388783, 0.400428,
0.43096, 0.462397, 0.479469, 0.499329, 0.534526, 0.568631,
0.589218
};
static const float iac_weights2[31] = {
0.000375307, 0.000450455, 0.000612191, 0.000297262, 0.000202956,
0.000484887, 0.000511777, 0.000686431, 0.00108256, 0.00185267,
0.00321869, 0.00541861, 0.00860266, 0.012726, 0.0219151,
0.0269104, 0.0316774, 0.0426107, 0.046113, 0.0494974,
0.0608692, 0.0734633, 0.0780208, 0.0844921, 0.103034,
0.124606, 0.137421, 0.153336, 0.184296, 0.217792,
0.239742
};
static const float imc_weights1[31] = {
0.119595, 0.123124, 0.129192, 9.97377e-2, 8.1923e-2, 9.61153e-2, 8.77885e-2, 8.61174e-2,
9.00882e-2, 9.91658e-2, 0.112991, 0.131126, 0.152886, 0.177292, 0.221782, 0.244917, 0.267386,