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aac: Don't bias output during the IMDCT if SBR will be used.

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Originally committed as revision 22515 to svn://svn.ffmpeg.org/ffmpeg/trunk
release/0.6
Alex Converse 15 years ago
parent 7c074320ba
commit f8a93a2036
2 changed files with 18 additions and 17 deletions
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  1. 27
      libavcodec/aac.c
  2. 8
      libavcodec/aacsbr.c

27
libavcodec/aac.c
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@ -1719,7 +1719,7 @@ static void apply_tns(float coef[1024], TemporalNoiseShaping *tns,
/**
* Conduct IMDCT and windowing.
*/
static void imdct_and_windowing(AACContext *ac, SingleChannelElement *sce)
static void imdct_and_windowing(AACContext *ac, SingleChannelElement *sce, float bias)
{
IndividualChannelStream *ics = &sce->ics;
float *in = sce->coeffs;
@ -1751,29 +1751,29 @@ static void imdct_and_windowing(AACContext *ac, SingleChannelElement *sce)
*/
if ((ics->window_sequence[1] == ONLY_LONG_SEQUENCE || ics->window_sequence[1] == LONG_STOP_SEQUENCE) &&
(ics->window_sequence[0] == ONLY_LONG_SEQUENCE || ics->window_sequence[0] == LONG_START_SEQUENCE)) {
ac->dsp.vector_fmul_window( out, saved, buf, lwindow_prev, ac->add_bias, 512);
ac->dsp.vector_fmul_window( out, saved, buf, lwindow_prev, bias, 512);
} else {
for (i = 0; i < 448; i++)
out[i] = saved[i] + ac->add_bias;
out[i] = saved[i] + bias;
if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
ac->dsp.vector_fmul_window(out + 448 + 0*128, saved + 448, buf + 0*128, swindow_prev, ac->add_bias, 64);
ac->dsp.vector_fmul_window(out + 448 + 1*128, buf + 0*128 + 64, buf + 1*128, swindow, ac->add_bias, 64);
ac->dsp.vector_fmul_window(out + 448 + 2*128, buf + 1*128 + 64, buf + 2*128, swindow, ac->add_bias, 64);
ac->dsp.vector_fmul_window(out + 448 + 3*128, buf + 2*128 + 64, buf + 3*128, swindow, ac->add_bias, 64);
ac->dsp.vector_fmul_window(temp, buf + 3*128 + 64, buf + 4*128, swindow, ac->add_bias, 64);
ac->dsp.vector_fmul_window(out + 448 + 0*128, saved + 448, buf + 0*128, swindow_prev, bias, 64);
ac->dsp.vector_fmul_window(out + 448 + 1*128, buf + 0*128 + 64, buf + 1*128, swindow, bias, 64);
ac->dsp.vector_fmul_window(out + 448 + 2*128, buf + 1*128 + 64, buf + 2*128, swindow, bias, 64);
ac->dsp.vector_fmul_window(out + 448 + 3*128, buf + 2*128 + 64, buf + 3*128, swindow, bias, 64);
ac->dsp.vector_fmul_window(temp, buf + 3*128 + 64, buf + 4*128, swindow, bias, 64);
memcpy( out + 448 + 4*128, temp, 64 * sizeof(float));
} else {
ac->dsp.vector_fmul_window(out + 448, saved + 448, buf, swindow_prev, ac->add_bias, 64);
ac->dsp.vector_fmul_window(out + 448, saved + 448, buf, swindow_prev, bias, 64);
for (i = 576; i < 1024; i++)
out[i] = buf[i-512] + ac->add_bias;
out[i] = buf[i-512] + bias;
}
}
// buffer update
if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
for (i = 0; i < 64; i++)
saved[i] = temp[64 + i] - ac->add_bias;
saved[i] = temp[64 + i] - bias;
ac->dsp.vector_fmul_window(saved + 64, buf + 4*128 + 64, buf + 5*128, swindow, 0, 64);
ac->dsp.vector_fmul_window(saved + 192, buf + 5*128 + 64, buf + 6*128, swindow, 0, 64);
ac->dsp.vector_fmul_window(saved + 320, buf + 6*128 + 64, buf + 7*128, swindow, 0, 64);
@ -1884,6 +1884,7 @@ static void apply_channel_coupling(AACContext *ac, ChannelElement *cc,
static void spectral_to_sample(AACContext *ac)
{
int i, type;
float imdct_bias = (ac->m4ac.sbr <= 0) ? ac->add_bias : 0.0f;
for (type = 3; type >= 0; type--) {
for (i = 0; i < MAX_ELEM_ID; i++) {
ChannelElement *che = ac->che[type][i];
@ -1897,14 +1898,14 @@ static void spectral_to_sample(AACContext *ac)
if (type <= TYPE_CPE)
apply_channel_coupling(ac, che, type, i, BETWEEN_TNS_AND_IMDCT, apply_dependent_coupling);
if (type != TYPE_CCE || che->coup.coupling_point == AFTER_IMDCT) {
imdct_and_windowing(ac, &che->ch[0]);
imdct_and_windowing(ac, &che->ch[0], imdct_bias);
if (ac->m4ac.sbr > 0) {
ff_sbr_dequant(ac, &che->sbr, type == TYPE_CPE ? TYPE_CPE : TYPE_SCE);
ff_sbr_apply(ac, &che->sbr, 0, che->ch[0].ret, che->ch[0].ret);
}
}
if (type == TYPE_CPE) {
imdct_and_windowing(ac, &che->ch[1]);
imdct_and_windowing(ac, &che->ch[1], imdct_bias);
if (ac->m4ac.sbr > 0)
ff_sbr_apply(ac, &che->sbr, 1, che->ch[1].ret, che->ch[1].ret);
}

8
libavcodec/aacsbr.c
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@ -1126,14 +1126,14 @@ static void sbr_dequant(SpectralBandReplication *sbr, int id_aac)
*/
static void sbr_qmf_analysis(DSPContext *dsp, RDFTContext *rdft, const float *in, float *x,
float z[320], float W[2][32][32][2],
float bias, float scale)
float scale)
{
int i, k;
memcpy(W[0], W[1], sizeof(W[0]));
memcpy(x , x+1024, (320-32)*sizeof(x[0]));
if (scale != 1.0f || bias != 0.0f)
if (scale != 1.0f)
for (i = 0; i < 1024; i++)
x[288 + i] = (in[i] - bias) * scale;
x[288 + i] = in[i] * scale;
else
memcpy(x+288, in, 1024*sizeof(*x));
for (i = 0; i < 32; i++) { // numTimeSlots*RATE = 16*2 as 960 sample frames
@ -1719,7 +1719,7 @@ void ff_sbr_apply(AACContext *ac, SpectralBandReplication *sbr, int ch,
/* decode channel */
sbr_qmf_analysis(&ac->dsp, &sbr->rdft, in, sbr->data[ch].analysis_filterbank_samples,
(float*)sbr->qmf_filter_scratch,
sbr->data[ch].W, ac->add_bias, 1/(-1024 * ac->sf_scale));
sbr->data[ch].W, 1/(-1024 * ac->sf_scale));
sbr_lf_gen(ac, sbr, sbr->X_low, sbr->data[ch].W);
if (sbr->start) {
sbr_hf_inverse_filter(sbr->alpha0, sbr->alpha1, sbr->X_low, sbr->k[0]);

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