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WMA decoder improvement, output closer to the dmo binary. 

Patch by Ian Braithwaite ian braithwaite dot dk

[Ffmpeg-devel] WMA decoder improvement, 2007-03-28 15:50

Originally committed as revision 8627 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Ian Braithwaite 2007-04-04 13:49:55 +00:00 committed by Benjamin Larsson
parent 047549d382
commit 5bd526d9ad
2 changed files with 24 additions and 56 deletions
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1
libavcodec/wma.h
View File

@ -107,6 +107,7 @@ typedef struct WMACodecContext {
int block_pos; ///< current position in frame
uint8_t ms_stereo; ///< true if mid/side stereo mode
uint8_t channel_coded[MAX_CHANNELS]; ///< true if channel is coded
int exponents_bsize[MAX_CHANNELS]; ///< log2 ratio frame/exp. length
DECLARE_ALIGNED_16(float, exponents[MAX_CHANNELS][BLOCK_MAX_SIZE]);
float max_exponent[MAX_CHANNELS];
int16_t coefs1[MAX_CHANNELS][BLOCK_MAX_SIZE];

79
libavcodec/wmadec.c
View File

@ -129,35 +129,6 @@ static int wma_decode_init(AVCodecContext * avctx)
return 0;
}
/**
* interpolate values for a bigger or smaller block. The block must
* have multiple sizes
*/
static void interpolate_array(float *scale, int old_size, int new_size)
{
int i, j, jincr, k;
float v;
if (new_size > old_size) {
jincr = new_size / old_size;
j = new_size;
for(i = old_size - 1; i >=0; i--) {
v = scale[i];
k = jincr;
do {
scale[--j] = v;
} while (--k);
}
} else if (new_size < old_size) {
j = 0;
jincr = old_size / new_size;
for(i = 0; i < new_size; i++) {
scale[i] = scale[j];
j += jincr;
}
}
}
/**
* compute x^-0.25 with an exponent and mantissa table. We use linear
* interpolation to reduce the mantissa table size at a small speed
@ -378,7 +349,7 @@ static void wma_window(WMACodecContext *s, float *out)
static int wma_decode_block(WMACodecContext *s)
{
int n, v, a, ch, code, bsize;
int coef_nb_bits, total_gain, parse_exponents;
int coef_nb_bits, total_gain;
int nb_coefs[MAX_CHANNELS];
float mdct_norm;
@ -493,13 +464,9 @@ static int wma_decode_block(WMACodecContext *s)
}
}
/* exposant can be interpolated in short blocks. */
parse_exponents = 1;
if (s->block_len_bits != s->frame_len_bits) {
parse_exponents = get_bits(&s->gb, 1);
}
if (parse_exponents) {
/* exponents can be reused in short blocks. */
if ((s->block_len_bits == s->frame_len_bits) ||
get_bits(&s->gb, 1)) {
for(ch = 0; ch < s->nb_channels; ch++) {
if (s->channel_coded[ch]) {
if (s->use_exp_vlc) {
@ -508,13 +475,7 @@ static int wma_decode_block(WMACodecContext *s)
} else {
decode_exp_lsp(s, ch);
}
}
}
} else {
for(ch = 0; ch < s->nb_channels; ch++) {
if (s->channel_coded[ch]) {
interpolate_array(s->exponents[ch], 1 << s->prev_block_len_bits,
s->block_len);
s->exponents_bsize[ch] = bsize;
}
}
}
@ -588,12 +549,13 @@ static int wma_decode_block(WMACodecContext *s)
for(ch = 0; ch < s->nb_channels; ch++) {
if (s->channel_coded[ch]) {
int16_t *coefs1;
float *coefs, *exponents, mult, mult1, noise, *exp_ptr;
int i, j, n, n1, last_high_band;
float *coefs, *exponents, mult, mult1, noise;
int i, j, n, n1, last_high_band, esize;
float exp_power[HIGH_BAND_MAX_SIZE];
coefs1 = s->coefs1[ch];
exponents = s->exponents[ch];
esize = s->exponents_bsize[ch];
mult = pow(10, total_gain * 0.05) / s->max_exponent[ch];
mult *= mdct_norm;
coefs = s->coefs[ch];
@ -601,16 +563,16 @@ static int wma_decode_block(WMACodecContext *s)
mult1 = mult;
/* very low freqs : noise */
for(i = 0;i < s->coefs_start; i++) {
*coefs++ = s->noise_table[s->noise_index] * (*exponents++) * mult1;
*coefs++ = s->noise_table[s->noise_index] *
exponents[i<<bsize>>esize] * mult1;
s->noise_index = (s->noise_index + 1) & (NOISE_TAB_SIZE - 1);
}
n1 = s->exponent_high_sizes[bsize];
/* compute power of high bands */
exp_ptr = exponents +
s->high_band_start[bsize] -
s->coefs_start;
exponents = s->exponents[ch] +
(s->high_band_start[bsize]<<bsize);
last_high_band = 0; /* avoid warning */
for(j=0;j<n1;j++) {
n = s->exponent_high_bands[s->frame_len_bits -
@ -619,17 +581,18 @@ static int wma_decode_block(WMACodecContext *s)
float e2, v;
e2 = 0;
for(i = 0;i < n; i++) {
v = exp_ptr[i];
v = exponents[i<<bsize>>esize];
e2 += v * v;
}
exp_power[j] = e2 / n;
last_high_band = j;
tprintf(s->avctx, "%d: power=%f (%d)\n", j, exp_power[j], n);
}
exp_ptr += n;
exponents += n<<bsize;
}
/* main freqs and high freqs */
exponents = s->exponents[ch] + (s->coefs_start<<bsize);
for(j=-1;j<n1;j++) {
if (j < 0) {
n = s->high_band_start[bsize] -
@ -648,21 +611,25 @@ static int wma_decode_block(WMACodecContext *s)
for(i = 0;i < n; i++) {
noise = s->noise_table[s->noise_index];
s->noise_index = (s->noise_index + 1) & (NOISE_TAB_SIZE - 1);
*coefs++ = (*exponents++) * noise * mult1;
*coefs++ = noise *
exponents[i<<bsize>>esize] * mult1;
}
exponents += n<<bsize;
} else {
/* coded values + small noise */
for(i = 0;i < n; i++) {
noise = s->noise_table[s->noise_index];
s->noise_index = (s->noise_index + 1) & (NOISE_TAB_SIZE - 1);
*coefs++ = ((*coefs1++) + noise) * (*exponents++) * mult;
*coefs++ = ((*coefs1++) + noise) *
exponents[i<<bsize>>esize] * mult;
}
exponents += n<<bsize;
}
}
/* very high freqs : noise */
n = s->block_len - s->coefs_end[bsize];
mult1 = mult * exponents[-1];
mult1 = mult * exponents[((-1<<bsize))>>esize];
for(i = 0; i < n; i++) {
*coefs++ = s->noise_table[s->noise_index] * mult1;
s->noise_index = (s->noise_index + 1) & (NOISE_TAB_SIZE - 1);
@ -673,7 +640,7 @@ static int wma_decode_block(WMACodecContext *s)
*coefs++ = 0.0;
n = nb_coefs[ch];
for(i = 0;i < n; i++) {
*coefs++ = coefs1[i] * exponents[i] * mult;
*coefs++ = coefs1[i] * exponents[i<<bsize>>esize] * mult;
}
n = s->block_len - s->coefs_end[bsize];
for(i = 0;i < n; i++)