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+/******************************** MPEG Audio Encoder **************************
+
+ (C) Copyright Fraunhofer IIS (1997)
+ 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.
+
+
+ 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.
+
+ $Id$
+ Initial author: M. Werner
+ contents/description: Chaos measure calculation
+
+******************************************************************************/
+
+#include "chaosmeasure.h"
+
+/*****************************************************************************
+ functionname: FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast
+ description: Eberlein method of chaos measure calculation by high-pass
+ filtering amplitude spectrum
+ A special case of FDKaacEnc_CalculateChaosMeasureTonalGeneric --
+ highly optimized
+*****************************************************************************/
+static void
+FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast( FIXP_DBL *RESTRICT paMDCTDataNM0,
+ INT numberOfLines,
+ FIXP_DBL *RESTRICT chaosMeasure )
+{
+ INT i, j;
+
+ /* calculate chaos measure by "peak filter" */
+ for (i=0; i<2; i++) {
+ /* make even and odd pass through data */
+ FIXP_DBL left,center; /* left, center tap of filter */
+
+ left = (FIXP_DBL)((LONG)paMDCTDataNM0[i]^((LONG)paMDCTDataNM0[i]>>(DFRACT_BITS-1)));
+ center = (FIXP_DBL)((LONG)paMDCTDataNM0[i+2]^((LONG)paMDCTDataNM0[i+2]>>(DFRACT_BITS-1)));
+
+ for (j = i+2; j < numberOfLines - 2; j+=2) {
+ FIXP_DBL right = (FIXP_DBL)((LONG)paMDCTDataNM0[j+2]^((LONG)paMDCTDataNM0[j+2]>>(DFRACT_BITS-1)));
+ FIXP_DBL tmp = (left>>1)+(right>>1);
+
+ if (tmp < center ) {
+ INT leadingBits = CntLeadingZeros(center)-1;
+ tmp = schur_div(tmp<<leadingBits, center<<leadingBits, 8);
+ chaosMeasure[j] = fMult(tmp,tmp);
+ }
+ else {
+ chaosMeasure[j] = (FIXP_DBL)MAXVAL_DBL;
+ }
+
+ left = center;
+ center = right;
+ }
+ }
+
+ /* provide chaos measure for first few lines */
+ chaosMeasure[0] = chaosMeasure[2];
+ chaosMeasure[1] = chaosMeasure[2];
+
+ /* provide chaos measure for last few lines */
+ for (i = (numberOfLines-3); i < numberOfLines; i++)
+ chaosMeasure[i] = FL2FXCONST_DBL(0.5);
+}
+
+
+/*****************************************************************************
+ functionname: FDKaacEnc_CalculateChaosMeasure
+ description: calculates a chaosmeasure for every line, different methods
+ are available. 0 means tonal, 1 means noiselike
+ returns:
+ input: MDCT data, number of lines
+ output: chaosMeasure
+*****************************************************************************/
+void
+FDKaacEnc_CalculateChaosMeasure( FIXP_DBL *paMDCTDataNM0,
+ INT numberOfLines,
+ FIXP_DBL *chaosMeasure )
+
+{
+ FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast( paMDCTDataNM0,
+ numberOfLines,
+ chaosMeasure );
+}
+