1 files changed, 148 insertions, 0 deletions
diff --git a/libAACdec/src/ldfiltbank.cpp b/libAACdec/src/ldfiltbank.cpp
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+++ 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);
+}
+
+
+
+