From 712209d5672b39dd35abb59e8bea7907ac6b219f Mon Sep 17 00:00:00 2001 From: Alex Converse Date: Tue, 8 Jun 2010 01:57:06 +0000 Subject: 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 4a3377d..3cc927a 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 ]; -- cgit v1.1