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authorDave Burke <daveburke@google.com>2012-04-17 09:51:45 -0700
committerDave Burke <daveburke@google.com>2012-04-17 23:04:43 -0700
commit9bf37cc9712506b2483650c82d3c41152337ef7e (patch)
tree77db44e2bae06e3d144b255628be2b7a55c581d3 /libAACdec/src/ldfiltbank.cpp
parenta37315fe10ee143d6d0b28c19d41a476a23e63ea (diff)
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Fraunhofer AAC codec.
License boilerplate update to follow. Change-Id: I2810460c11a58b6d148d84673cc031f3685e79b5
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diff --git a/libAACdec/src/ldfiltbank.cpp b/libAACdec/src/ldfiltbank.cpp
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+/***************************************************************************\
+ *
+ * (C) copyright Fraunhofer - IIS (2006)
+ All Rights Reserved
+
+ Please be advised that this software and/or program delivery is
+ Confidential Information of Fraunhofer and subject to and covered by the
+
+ Fraunhofer IIS Software Evaluation Agreement
+ between Google Inc. and Fraunhofer
+ effective and in full force since March 1, 2012.
+
+ You may use this software and/or program only under the terms and
+ conditions described in the above mentioned Fraunhofer IIS Software
+ Evaluation Agreement. Any other and/or further use requires a separate agreement.
+
+*
+ * filename: ldfiltbank.c
+ * project : MPEG-4 Audio Decoder
+ * contents/description: low delay filterbank
+ *
+ * This software and/or program is protected by copyright law and
+ * international treaties. Any reproduction or distribution of this
+ * software and/or program, or any portion of it, may result in severe
+ * civil and criminal penalties, and will be prosecuted to the maximum
+ * extent possible under law.
+ *
+ * $Id$
+ *
+\***************************************************************************/
+
+#include "ldfiltbank.h"
+
+
+#include "aac_rom.h"
+#include "dct.h"
+#include "FDK_tools_rom.h"
+#include "mdct.h"
+
+#define LDFB_HEADROOM 2
+
+static void multE2_DinvF_fdk(INT_PCM *output, FIXP_DBL* x, const FIXP_WTB* fb, FIXP_DBL* z, const int N, const int stride)
+{
+ int i, scale;
+
+ /* scale for FIXP_DBL -> INT_PCM conversion. */
+ scale = (DFRACT_BITS - SAMPLE_BITS) - LDFB_HEADROOM;
+
+ for(i=0;i<N/4;i++)
+ {
+ FIXP_DBL z0, z2, tmp;
+
+ z2 = x[N/2+i];
+ z0 = z2 + ( fMultDiv2(z[N/2+i], fb[2*N + i]) >> (-WTS2-1) );
+
+ z[N/2+i] = x[N/2-1-i] + ( fMultDiv2(z[N + i], fb[2*N + N/2 + i]) >> (-WTS2-1) );
+
+ tmp = ( fMultDiv2(z[N/2+i], fb[N+N/2-1-i]) + fMultDiv2(z[i], fb[N+N/2+i]) ) ;
+
+#if (SAMPLE_BITS <= 16)
+ FDK_ASSERT( (-WTS1-1 + scale) >= 0);
+ output[(N*3/4-1-i)*stride] = (INT_PCM)SATURATE_RIGHT_SHIFT(tmp, -WTS1-1 + scale, SAMPLE_BITS);
+#else
+ FDK_ASSERT( (WTS1+1 - scale) >= 0);
+ output[(N*3/4-1-i)*stride] = (INT_PCM)SATURATE_LEFT_SHIFT(tmp, WTS1+1 - scale, SAMPLE_BITS);
+#endif
+
+ z[i] = z0;
+ z[N + i] = z2;
+ }
+
+ for(i=N/4;i<N/2;i++)
+ {
+ FIXP_DBL z0, z2, tmp0, tmp1;
+
+ z2 = x[N/2+i];
+ z0 = z2 + ( fMultDiv2(z[N/2+i], fb[2*N + i]) >> (-WTS2-1) );
+
+ z[N/2+i] = x[N/2-1-i] + ( fMultDiv2(z[N + i], fb[2*N + N/2 + i]) >> (-WTS2-1) );
+
+ tmp0 = ( fMultDiv2(z[N/2+i], fb[N/2-1-i]) + fMultDiv2(z[i], fb[N/2+i]) ) ;
+ tmp1 = ( fMultDiv2(z[N/2+i], fb[N+N/2-1-i]) + fMultDiv2(z[i], fb[N+N/2+i]) ) ;
+
+#if (SAMPLE_BITS <= 16)
+ FDK_ASSERT( (-WTS0-1 + scale) >= 0);
+ output[(i-N/4)*stride] = (INT_PCM)SATURATE_RIGHT_SHIFT(tmp0, -WTS0-1 + scale, SAMPLE_BITS);
+ output[(N*3/4-1-i)*stride] = (INT_PCM)SATURATE_RIGHT_SHIFT(tmp1, -WTS1-1 + scale, SAMPLE_BITS);
+#else
+ FDK_ASSERT( (WTS0+1 - scale) >= 0);
+ output[(i-N/4)*stride] = (INT_PCM)SATURATE_LEFT_SHIFT(tmp0, WTS0+1 - scale, SAMPLE_BITS);
+ output[(N*3/4-1-i)*stride] = (INT_PCM)SATURATE_LEFT_SHIFT(tmp1, WTS1+1 - scale, SAMPLE_BITS);
+#endif
+ z[i] = z0;
+ z[N + i] = z2;
+ }
+
+ /* Exchange quarter parts of x to bring them in the "right" order */
+ for(i=0;i<N/4;i++)
+ {
+ FIXP_DBL tmp0 = fMultDiv2(z[i], fb[N/2+i]);
+
+#if (SAMPLE_BITS <= 16)
+ FDK_ASSERT( (-WTS0-1 + scale) >= 0);
+ output[(N*3/4 + i)*stride] = (INT_PCM)SATURATE_RIGHT_SHIFT(tmp0, -WTS0-1 + scale, SAMPLE_BITS);
+#else
+ FDK_ASSERT( (WTS0+1 - scale) >= 0);
+ output[(N*3/4 + i)*stride] = (INT_PCM)SATURATE_LEFT_SHIFT(tmp0, WTS0+1 - scale, SAMPLE_BITS);
+#endif
+ }
+}
+
+int InvMdctTransformLowDelay_fdk (FIXP_DBL *mdctData, const int mdctData_e, INT_PCM *output, FIXP_DBL *fs_buffer, const int stride, const int N) {
+
+ const FIXP_WTB *coef;
+ FIXP_DBL gain = (FIXP_DBL)0;
+ int scale = mdctData_e + MDCT_OUT_HEADROOM - LDFB_HEADROOM; /* The LDFB_HEADROOM is compensated inside multE2_DinvF_fdk() below */
+
+ /* Select LD window slope */
+ if (N == 512)
+ coef = (FIXP_WTB*)LowDelaySynthesis512;
+ else
+ coef = (FIXP_WTB*)LowDelaySynthesis480;
+
+ /*
+ Apply exponent and 1/N factor.
+ Note: "scale" is off by one because for LD_MDCT the window length is twice
+ the window length of a regular MDCT. This is corrected inside multE2_DinvF_fdk().
+ Refer to ISO/IEC 14496-3:2009 page 277, chapter 4.6.20.2 "Low Delay Window".
+ */
+ imdct_gain(&gain, &scale, N);
+
+ dct_IV(mdctData, N, &scale);
+
+ if (gain != (FIXP_DBL)0) {
+ scaleValuesWithFactor(mdctData, gain, N, scale);
+ } else {
+ scaleValues(mdctData, N, scale);
+ }
+
+ /* Since all exponent and factors have been applied, current exponent is zero. */
+ multE2_DinvF_fdk(output, mdctData, coef, fs_buffer, N, stride);
+
+ return (1);
+}
+
+
+
+