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authorAlex Converse <alex.converse@gmail.com>2010-06-07 21:52:08 +0000
committerAlex Converse <alex.converse@gmail.com>2010-06-07 21:52:08 +0000
commit932963b8e2e96b3d8c7506d9cf093b54f89d1e78 (patch)
tree834d494d60c3f8fce93438b53c5f4164698ee984 /libavcodec/aacsbr.c
parent082a0a33c45d9bc4f3a8d9b1365b5416485ed388 (diff)
downloadffmpeg-932963b8e2e96b3d8c7506d9cf093b54f89d1e78.tar.gz
Rewrite the SBR decoder QMF analysis filter on top of the IMDCT instead of the RDFT.
This is based on a procedure to implement the filterbank on the DCT-IV described in Hsu, H.W. et al. "A Complex Quadrature Mirror Filterbanks for MPEG-4 HE-AAC" http://sites.google.com/site/wenchiehlee1020/Papers/ComplexFB_AES_121paper144.pdf Originally committed as revision 23516 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/aacsbr.c')
-rw-r--r--libavcodec/aacsbr.c44
1 files changed, 16 insertions, 28 deletions
diff --git a/libavcodec/aacsbr.c b/libavcodec/aacsbr.c
index 27c379e15b..540c30a5aa 100644
--- a/libavcodec/aacsbr.c
+++ b/libavcodec/aacsbr.c
@@ -71,9 +71,6 @@ enum {
static VLC vlc_sbr[10];
static const int8_t vlc_sbr_lav[10] =
{ 60, 60, 24, 24, 31, 31, 12, 12, 31, 12 };
-static DECLARE_ALIGNED(16, float, analysis_cos_pre)[64];
-static DECLARE_ALIGNED(16, float, analysis_sin_pre)[64];
-static DECLARE_ALIGNED(16, float, analysis_cossin_post)[32][2];
static const DECLARE_ALIGNED(16, float, zero64)[64];
#define SBR_INIT_VLC_STATIC(num, size) \
@@ -116,16 +113,6 @@ av_cold void ff_aac_sbr_init(void)
SBR_INIT_VLC_STATIC(8, 592);
SBR_INIT_VLC_STATIC(9, 512);
- for (n = 0; n < 64; n++) {
- float pre = M_PI * n / 64;
- analysis_cos_pre[n] = cosf(pre);
- analysis_sin_pre[n] = sinf(pre);
- }
- for (k = 0; k < 32; k++) {
- float post = M_PI * (k + 0.5) / 128;
- analysis_cossin_post[k][0] = 4.0 * cosf(post);
- analysis_cossin_post[k][1] = -4.0 * sinf(post);
- }
for (n = 1; n < 320; n++)
sbr_qmf_window_us[320 + n] = sbr_qmf_window_us[320 - n];
sbr_qmf_window_us[384] = -sbr_qmf_window_us[384];
@@ -142,13 +129,13 @@ av_cold void ff_aac_sbr_ctx_init(SpectralBandReplication *sbr)
sbr->data[0].synthesis_filterbank_samples_offset = SBR_SYNTHESIS_BUF_SIZE - (1280 - 128);
sbr->data[1].synthesis_filterbank_samples_offset = SBR_SYNTHESIS_BUF_SIZE - (1280 - 128);
ff_mdct_init(&sbr->mdct, 7, 1, 1.0/64);
- ff_rdft_init(&sbr->rdft, 6, IDFT_R2C);
+ ff_mdct_init(&sbr->mdct_ana, 7, 1, -2.0);
}
av_cold void ff_aac_sbr_ctx_close(SpectralBandReplication *sbr)
{
ff_mdct_end(&sbr->mdct);
- ff_rdft_end(&sbr->rdft);
+ ff_mdct_end(&sbr->mdct_ana);
}
static int qsort_comparison_function_int16(const void *a, const void *b)
@@ -1139,7 +1126,7 @@ static void sbr_dequant(SpectralBandReplication *sbr, int id_aac)
* @param x pointer to the beginning of the first sample window
* @param W array of complex-valued samples split into subbands
*/
-static void sbr_qmf_analysis(DSPContext *dsp, RDFTContext *rdft, const float *in, float *x,
+static void sbr_qmf_analysis(DSPContext *dsp, RDFTContext *mdct, const float *in, float *x,
float z[320], float W[2][32][32][2],
float scale)
{
@@ -1156,19 +1143,20 @@ static void sbr_qmf_analysis(DSPContext *dsp, RDFTContext *rdft, const float *in
dsp->vector_fmul_reverse(z, sbr_qmf_window_ds, x, 320);
for (k = 0; k < 64; k++) {
float f = z[k] + z[k + 64] + z[k + 128] + z[k + 192] + z[k + 256];
- z[k] = f * analysis_cos_pre[k];
- z[k+64] = f;
+ z[k] = f;
}
- ff_rdft_calc(rdft, z);
- re = z[0] * 0.5f;
- im = 0.5f * dsp->scalarproduct_float(z+64, analysis_sin_pre, 64);
- W[1][i][0][0] = re * analysis_cossin_post[0][0] - im * analysis_cossin_post[0][1];
- W[1][i][0][1] = re * analysis_cossin_post[0][1] + im * analysis_cossin_post[0][0];
+ //Shuffle to IMDCT
+ z[64] = z[0];
for (k = 1; k < 32; k++) {
- re = z[2*k ] - re;
- im = z[2*k+1] - im;
- W[1][i][k][0] = re * analysis_cossin_post[k][0] - im * analysis_cossin_post[k][1];
- W[1][i][k][1] = re * analysis_cossin_post[k][1] + im * analysis_cossin_post[k][0];
+ z[64+2*k-1] = z[ k];
+ z[64+2*k ] = -z[64-k];
+ }
+ z[64+63] = z[32];
+
+ ff_imdct_half(mdct, z, z+64);
+ for (k = 0; k < 32; k++) {
+ W[1][i][k][0] = -z[63-k];
+ W[1][i][k][1] = z[k];
}
x += 32;
}
@@ -1730,7 +1718,7 @@ void ff_sbr_apply(AACContext *ac, SpectralBandReplication *sbr, int id_aac,
}
for (ch = 0; ch < nch; ch++) {
/* decode channel */
- sbr_qmf_analysis(&ac->dsp, &sbr->rdft, ch ? R : L, sbr->data[ch].analysis_filterbank_samples,
+ sbr_qmf_analysis(&ac->dsp, &sbr->mdct_ana, ch ? R : L, sbr->data[ch].analysis_filterbank_samples,
(float*)sbr->qmf_filter_scratch,
sbr->data[ch].W, 1/(-1024 * ac->sf_scale));
sbr_lf_gen(ac, sbr, sbr->X_low, sbr->data[ch].W);