From 712209d5672b39dd35abb59e8bea7907ac6b219f Mon Sep 17 00:00:00 2001
From: Alex Converse <alex.converse@gmail.com>
Date: Tue, 8 Jun 2010 01:57:06 +0000
Subject: [PATCH] Base downsampled SBR synthesis filterbank on a single IMDCT.
Based on Han-Wen Hsu, et al. "Fast Complex Quadrature Mirror Filterbanks for
MPEG-4 HE-AAC"
Originally committed as revision 23519 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavcodec/aacsbr.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/libavcodec/aacsbr.c b/libavcodec/aacsbr.c
index 4a3377d812f..3cc927a779c 100644
--- a/libavcodec/aacsbr.c
+++ b/libavcodec/aacsbr.c
@@ -1184,21 +1184,22 @@ static void sbr_qmf_synthesis(DSPContext *dsp, FFTContext *mdct,
*v_off -= 128 >> div;
}
v = v0 + *v_off;
+ if (div) {
+ for (n = 0; n < 32; n++) {
+ X[0][i][ n] = -X[0][i][n];
+ X[0][i][32+n] = X[1][i][31-n];
+ }
+ ff_imdct_half(mdct, mdct_buf[0], X[0][i]);
+ for (n = 0; n < 32; n++) {
+ v[ n] = mdct_buf[0][63 - 2*n];
+ v[63 - n] = -mdct_buf[0][62 - 2*n];
+ }
+ } else {
for (n = 1; n < 64 >> div; n+=2) {
X[1][i][n] = -X[1][i][n];
}
- if (div) {
- memset(X[0][i]+32, 0, 32*sizeof(float));
- memset(X[1][i]+32, 0, 32*sizeof(float));
- }
ff_imdct_half(mdct, mdct_buf[0], X[0][i]);
ff_imdct_half(mdct, mdct_buf[1], X[1][i]);
- if (div) {
- for (n = 0; n < 32; n++) {
- v[ n] = -mdct_buf[0][63 - 2*n] + mdct_buf[1][2*n ];
- v[ 63 - n] = mdct_buf[0][62 - 2*n] + mdct_buf[1][2*n + 1];
- }
- } else {
for (n = 0; n < 64; n++) {
v[ n] = -mdct_buf[0][63 - n] + mdct_buf[1][ n ];
v[127 - n] = mdct_buf[0][63 - n] + mdct_buf[1][ n ];
--
GitLab