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/**
*@brief Uninitialize the decoder and free all resources.
*@param avctx codec context
*@return 0 on success, < 0 otherwise
*/
static av_cold int decode_end(AVCodecContext *avctx)
{
WMA3DecodeContext *s = avctx->priv_data;
int i;
av_freep(&s->num_sfb);
av_freep(&s->sfb_offsets);
av_freep(&s->subwoofer_cutoffs);
av_freep(&s->sf_offsets);
for (i=0 ; i<WMAPRO_BLOCK_SIZES ; i++)
ff_mdct_end(&s->mdct_ctx[i]);
return 0;
}
/**
*@brief Calculate a decorrelation matrix from the bitstream parameters.
*@param s codec context
*@param chgroup channel group for which the matrix needs to be calculated
*/
static void decode_decorrelation_matrix(WMA3DecodeContext* s,
WMA3ChannelGroup* chgroup)
{
int i;
int offset = 0;
int8_t rotation_offset[WMAPRO_MAX_CHANNELS * WMAPRO_MAX_CHANNELS];
memset(chgroup->decorrelation_matrix,0,
sizeof(float) *s->num_channels * s->num_channels);
for (i=0;i<chgroup->num_channels * (chgroup->num_channels - 1) >> 1;i++)
rotation_offset[i] = get_bits(&s->gb,6);
for (i=0;i<chgroup->num_channels;i++)
chgroup->decorrelation_matrix[chgroup->num_channels * i + i] =
get_bits1(&s->gb) ? 1.0 : -1.0;
for (i=1;i<chgroup->num_channels;i++) {
int x;
for (x=0;x<i;x++) {
int y;
for (y=0;y < i + 1 ; y++) {
float v1 = chgroup->decorrelation_matrix[x * chgroup->num_channels + y];
float v2 = chgroup->decorrelation_matrix[i * chgroup->num_channels + y];
int n = rotation_offset[offset + x];
float sinv;
float cosv;
if (n<32) {
sinv = sin64[n];
cosv = sin64[32-n];
} else {
sinv = sin64[64-n];
cosv = -sin64[n-32];
}
chgroup->decorrelation_matrix[y + x * chgroup->num_channels] =
(v1 * sinv) - (v2 * cosv);
chgroup->decorrelation_matrix[y + i * chgroup->num_channels] =
(v1 * cosv) + (v2 * sinv);
}
}
offset += i;
}
}
/**
*@brief Reconstruct the individual channel data.
*@param s codec context
*/
static void inverse_channel_transform(WMA3DecodeContext *s)
{
int i;
for (i=0;i<s->num_chgroups;i++) {
if (s->chgroup[i].transform == 1) {
/** M/S stereo decoding */
int16_t* sfb_offsets = s->cur_sfb_offsets;
float* ch0 = *sfb_offsets + s->channel[0].coeffs;
float* ch1 = *sfb_offsets++ + s->channel[1].coeffs;
const char* tb = s->chgroup[i].transform_band;
const char* tb_end = tb + s->num_bands;
while (tb < tb_end) {
const float* ch0_end = s->channel[0].coeffs +
FFMIN(*sfb_offsets,s->subframe_len);
if (*tb++ == 1) {
while (ch0 < ch0_end) {
const float v1 = *ch0;
const float v2 = *ch1;
*ch0++ = v1 - v2;
*ch1++ = v1 + v2;
}
} else {
while (ch0 < ch0_end) {
*ch0++ *= 181.0 / 128;
*ch1++ *= 181.0 / 128;
}
}
++sfb_offsets;
}
} else if (s->chgroup[i].transform) {
float data[WMAPRO_MAX_CHANNELS];
const int num_channels = s->chgroup[i].num_channels;
float** ch_data = s->chgroup[i].channel_data;
float** ch_end = ch_data + num_channels;
const int8_t* tb = s->chgroup[i].transform_band;
int16_t* sfb;
/** multichannel decorrelation */
for (sfb = s->cur_sfb_offsets ;
sfb < s->cur_sfb_offsets + s->num_bands;sfb++) {
if (*tb++ == 1) {
int y;
/** multiply values with the decorrelation_matrix */
for (y=sfb[0];y<FFMIN(sfb[1], s->subframe_len);y++) {
const float* mat = s->chgroup[i].decorrelation_matrix;
const float* data_end= data + num_channels;
float* data_ptr= data;
float** ch;
for (ch = ch_data;ch < ch_end; ch++)
*data_ptr++ = (*ch)[y];
for (ch = ch_data; ch < ch_end; ch++) {
float sum = 0;
data_ptr = data;
while (data_ptr < data_end)
sum += *data_ptr++ * *mat++;
(*ch)[y] = sum;
}
}
}
}
}
}
}
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