src/modules/audio_coding/codecs/iSAC/fix/source/filterbanks.c - vendor/opensource/webrtc - Git at Google

 /*
  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 /*
  * filterbanks.c
  *
  * This file contains function
  * WebRtcIsacfix_SplitAndFilter, and WebRtcIsacfix_FilterAndCombine
  * which implement filterbanks that produce decimated lowpass and
  * highpass versions of a signal, and performs reconstruction.
  *
  */

 #include "codec.h"
 #include "filterbank_tables.h"
 #include "settings.h"


 static void AllpassFilter2FixDec16(WebRtc_Word16 *InOut16, //Q0
                                    const WebRtc_Word16 *APSectionFactors, //Q15
                                    WebRtc_Word16 lengthInOut,
                                    WebRtc_Word16 NumberOfSections,
                                    WebRtc_Word32 *FilterState) //Q16
 {
   int n, j;
   WebRtc_Word32 a, b;

   for (j=0; j<NumberOfSections; j++) {
     for (n=0;n<lengthInOut;n++) {


       a = WEBRTC_SPL_MUL_16_16(APSectionFactors[j], InOut16[n]); //Q15*Q0=Q15
       a = WEBRTC_SPL_LSHIFT_W32(a, 1); // Q15 -> Q16
       b = WEBRTC_SPL_ADD_SAT_W32(a, FilterState[j]); //Q16+Q16=Q16
       a = WEBRTC_SPL_MUL_16_16_RSFT(-APSectionFactors[j], (WebRtc_Word16) WEBRTC_SPL_RSHIFT_W32(b, 16), 0); //Q15*Q0=Q15
       FilterState[j] = WEBRTC_SPL_ADD_SAT_W32(WEBRTC_SPL_LSHIFT_W32(a,1), WEBRTC_SPL_LSHIFT_W32((WebRtc_UWord32)InOut16[n],16)); // Q15<<1 + Q0<<16 = Q16 + Q16 = Q16
       InOut16[n] = (WebRtc_Word16) WEBRTC_SPL_RSHIFT_W32(b, 16); //Save as Q0

     }
   }

 }


 static void HighpassFilterFixDec32(
     WebRtc_Word16 *io,   /* Q0:input Q0: Output */
     WebRtc_Word16 len, /* length of input, Input */
     const WebRtc_Word16 *coeff, /* Coeff: [Q30hi Q30lo Q30hi Q30lo Q35hi Q35lo Q35hi Q35lo] */
     WebRtc_Word32 *state) /* Q4:filter state Input/Output */
 {
   int k;
   WebRtc_Word32 a, b, c, in;


   for (k=0; k<len; k++) {
     in = (WebRtc_Word32)io[k];
     /* Q35 * Q4 = Q39 ; shift 32 bit => Q7 */
     a = WEBRTC_SPL_MUL_32_32_RSFT32(coeff[2*2], coeff[2*2+1], state[0]);
     b = WEBRTC_SPL_MUL_32_32_RSFT32(coeff[2*3], coeff[2*3+1], state[1]);

     c = ((WebRtc_Word32)in) + WEBRTC_SPL_RSHIFT_W32(a+b, 7); // Q0
     //c = WEBRTC_SPL_RSHIFT_W32(c, 1); // Q-1
     io[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(c);  // Write output as Q0

     /* Q30 * Q4 = Q34 ; shift 32 bit => Q2 */
     a = WEBRTC_SPL_MUL_32_32_RSFT32(coeff[2*0], coeff[2*0+1], state[0]);
     b = WEBRTC_SPL_MUL_32_32_RSFT32(coeff[2*1], coeff[2*1+1], state[1]);

     c = WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)in, 2) - a - b; // New state in Q2
     c= (WebRtc_Word32)WEBRTC_SPL_SAT((WebRtc_Word32)536870911, c, (WebRtc_Word32)-536870912); // Check for wrap-around

     state[1] = state[0];
     state[0] = WEBRTC_SPL_LSHIFT_W32(c, 2); // Write state as Q4

   }
 }


 void WebRtcIsacfix_SplitAndFilter1(WebRtc_Word16 *pin,
                                    WebRtc_Word16 *LP16,
                                    WebRtc_Word16 *HP16,
                                    PreFiltBankstr *prefiltdata)
 {
   /* Function WebRtcIsacfix_SplitAndFilter */
   /* This function creates low-pass and high-pass decimated versions of part of
      the input signal, and part of the signal in the input 'lookahead buffer'. */

   int k;

   WebRtc_Word16 tempin_ch1[FRAMESAMPLES/2 + QLOOKAHEAD];
   WebRtc_Word16 tempin_ch2[FRAMESAMPLES/2 + QLOOKAHEAD];
   WebRtc_Word32 tmpState[WEBRTC_SPL_MUL_16_16(2,(QORDER-1))]; /* 4 */


   /* High pass filter */
   HighpassFilterFixDec32(pin, FRAMESAMPLES, WebRtcIsacfix_kHpStCoeffInQ30, prefiltdata->HPstates_fix);


   /* First Channel */
   for (k=0;k<FRAMESAMPLES/2;k++) {
     tempin_ch1[QLOOKAHEAD + k] = pin[1+WEBRTC_SPL_MUL_16_16(2, k)];
   }
   for (k=0;k<QLOOKAHEAD;k++) {
     tempin_ch1[k]=prefiltdata->INLABUF1_fix[k];
     prefiltdata->INLABUF1_fix[k]=pin[FRAMESAMPLES+1-WEBRTC_SPL_MUL_16_16(2, QLOOKAHEAD)+WEBRTC_SPL_MUL_16_16(2, k)];
   }

   /* Second Channel.  This is exactly like the first channel, except that the
      even samples are now filtered instead (lower channel). */
   for (k=0;k<FRAMESAMPLES/2;k++) {
     tempin_ch2[QLOOKAHEAD+k] = pin[WEBRTC_SPL_MUL_16_16(2, k)];
   }
   for (k=0;k<QLOOKAHEAD;k++) {
     tempin_ch2[k]=prefiltdata->INLABUF2_fix[k];
     prefiltdata->INLABUF2_fix[k]=pin[FRAMESAMPLES-WEBRTC_SPL_MUL_16_16(2, QLOOKAHEAD)+WEBRTC_SPL_MUL_16_16(2, k)];
   }


   /*obtain polyphase components by forward all-pass filtering through each channel */
   /* The all pass filtering automatically updates the filter states which are exported in the
      prefiltdata structure */
   AllpassFilter2FixDec16(tempin_ch1,WebRtcIsacfix_kUpperApFactorsQ15, FRAMESAMPLES/2 , NUMBEROFCHANNELAPSECTIONS, prefiltdata->INSTAT1_fix);
   AllpassFilter2FixDec16(tempin_ch2,WebRtcIsacfix_kLowerApFactorsQ15, FRAMESAMPLES/2 , NUMBEROFCHANNELAPSECTIONS, prefiltdata->INSTAT2_fix);

   for (k=0;k<WEBRTC_SPL_MUL_16_16(2, (QORDER-1));k++)
     tmpState[k] = prefiltdata->INSTAT1_fix[k];
   AllpassFilter2FixDec16(tempin_ch1 + FRAMESAMPLES/2,WebRtcIsacfix_kUpperApFactorsQ15, QLOOKAHEAD , NUMBEROFCHANNELAPSECTIONS, tmpState);
   for (k=0;k<WEBRTC_SPL_MUL_16_16(2, (QORDER-1));k++)
     tmpState[k] = prefiltdata->INSTAT2_fix[k];
   AllpassFilter2FixDec16(tempin_ch2 + FRAMESAMPLES/2,WebRtcIsacfix_kLowerApFactorsQ15, QLOOKAHEAD , NUMBEROFCHANNELAPSECTIONS, tmpState);


   /* Now Construct low-pass and high-pass signals as combinations of polyphase components */
   for (k=0; k<FRAMESAMPLES/2 + QLOOKAHEAD; k++) {
     WebRtc_Word32 tmp1, tmp2, tmp3;
     tmp1 = (WebRtc_Word32)tempin_ch1[k]; // Q0 -> Q0
     tmp2 = (WebRtc_Word32)tempin_ch2[k]; // Q0 -> Q0
     tmp3 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W32((tmp1 + tmp2), 1);/* low pass signal*/
     LP16[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp3); /*low pass */
     tmp3 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W32((tmp1 - tmp2), 1);/* high pass signal*/
     HP16[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp3); /*high pass */
   }

 }/*end of WebRtcIsacfix_SplitAndFilter */


 #ifdef WEBRTC_ISAC_FIX_NB_CALLS_ENABLED

 /* Without lookahead */
 void WebRtcIsacfix_SplitAndFilter2(WebRtc_Word16 *pin,
                                    WebRtc_Word16 *LP16,
                                    WebRtc_Word16 *HP16,
                                    PreFiltBankstr *prefiltdata)
 {
   /* Function WebRtcIsacfix_SplitAndFilter2 */
   /* This function creates low-pass and high-pass decimated versions of part of
      the input signal. */

   int k;

   WebRtc_Word16 tempin_ch1[FRAMESAMPLES/2];
   WebRtc_Word16 tempin_ch2[FRAMESAMPLES/2];


   /* High pass filter */
   HighpassFilterFixDec32(pin, FRAMESAMPLES, WebRtcIsacfix_kHpStCoeffInQ30, prefiltdata->HPstates_fix);


   /* First Channel */
   for (k=0;k<FRAMESAMPLES/2;k++) {
     tempin_ch1[k] = pin[1+WEBRTC_SPL_MUL_16_16(2, k)];
   }

   /* Second Channel.  This is exactly like the first channel, except that the
      even samples are now filtered instead (lower channel). */
   for (k=0;k<FRAMESAMPLES/2;k++) {
     tempin_ch2[k] = pin[WEBRTC_SPL_MUL_16_16(2, k)];
   }


   /*obtain polyphase components by forward all-pass filtering through each channel */
   /* The all pass filtering automatically updates the filter states which are exported in the
      prefiltdata structure */
   AllpassFilter2FixDec16(tempin_ch1,WebRtcIsacfix_kUpperApFactorsQ15, FRAMESAMPLES/2 , NUMBEROFCHANNELAPSECTIONS, prefiltdata->INSTAT1_fix);
   AllpassFilter2FixDec16(tempin_ch2,WebRtcIsacfix_kLowerApFactorsQ15, FRAMESAMPLES/2 , NUMBEROFCHANNELAPSECTIONS, prefiltdata->INSTAT2_fix);


   /* Now Construct low-pass and high-pass signals as combinations of polyphase components */
   for (k=0; k<FRAMESAMPLES/2; k++) {
     WebRtc_Word32 tmp1, tmp2, tmp3;
     tmp1 = (WebRtc_Word32)tempin_ch1[k]; // Q0 -> Q0
     tmp2 = (WebRtc_Word32)tempin_ch2[k]; // Q0 -> Q0
     tmp3 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W32((tmp1 + tmp2), 1);/* low pass signal*/
     LP16[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp3); /*low pass */
     tmp3 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W32((tmp1 - tmp2), 1);/* high pass signal*/
     HP16[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp3); /*high pass */
   }

 }/*end of WebRtcIsacfix_SplitAndFilter */

 #endif


 //////////////////////////////////////////////////////////
 ////////// Combining
 /* Function WebRtcIsacfix_FilterAndCombine */
 /* This is a decoder function that takes the decimated
    length FRAMESAMPLES/2 input low-pass and
    high-pass signals and creates a reconstructed fullband
    output signal of length FRAMESAMPLES. WebRtcIsacfix_FilterAndCombine
    is the sibling function of WebRtcIsacfix_SplitAndFilter */
 /* INPUTS:
    inLP: a length FRAMESAMPLES/2 array of input low-pass
    samples.
    inHP: a length FRAMESAMPLES/2 array of input high-pass
    samples.
    postfiltdata: input data structure containing the filterbank
    states from the previous decoding iteration.
    OUTPUTS:
    Out: a length FRAMESAMPLES array of output reconstructed
    samples (fullband) based on the input low-pass and
    high-pass signals.
    postfiltdata: the input data structure containing the filterbank
    states is updated for the next decoding iteration */
 void WebRtcIsacfix_FilterAndCombine1(WebRtc_Word16 *tempin_ch1,
                                      WebRtc_Word16 *tempin_ch2,
                                      WebRtc_Word16 *out16,
                                      PostFiltBankstr *postfiltdata)
 {
   int k;
   WebRtc_Word16 in[FRAMESAMPLES];

   /* all-pass filter the new upper channel signal. HOWEVER, use the all-pass filter factors
      that were used as a lower channel at the encoding side.  So at the decoder, the
      corresponding all-pass filter factors for each channel are swapped.*/

   AllpassFilter2FixDec16(tempin_ch1, WebRtcIsacfix_kLowerApFactorsQ15, FRAMESAMPLES/2, NUMBEROFCHANNELAPSECTIONS,postfiltdata->STATE_0_UPPER_fix);

   /* Now, all-pass filter the new lower channel signal. But since all-pass filter factors
      at the decoder are swapped from the ones at the encoder, the 'upper' channel
      all-pass filter factors (kUpperApFactors) are used to filter this new lower channel signal */

   AllpassFilter2FixDec16(tempin_ch2, WebRtcIsacfix_kUpperApFactorsQ15, FRAMESAMPLES/2, NUMBEROFCHANNELAPSECTIONS,postfiltdata->STATE_0_LOWER_fix);

   /* Merge outputs to form the full length output signal.*/
   for (k=0;k<FRAMESAMPLES/2;k++) {
     in[WEBRTC_SPL_MUL_16_16(2, k)]=tempin_ch2[k];
     in[WEBRTC_SPL_MUL_16_16(2, k)+1]=tempin_ch1[k];
   }

   /* High pass filter */
   HighpassFilterFixDec32(in, FRAMESAMPLES, WebRtcIsacfix_kHPStCoeffOut1Q30, postfiltdata->HPstates1_fix);
   HighpassFilterFixDec32(in, FRAMESAMPLES, WebRtcIsacfix_kHPStCoeffOut2Q30, postfiltdata->HPstates2_fix);

   for (k=0;k<FRAMESAMPLES;k++) {
     out16[k] = in[k];
   }
 }


 #ifdef WEBRTC_ISAC_FIX_NB_CALLS_ENABLED
 /* Function WebRtcIsacfix_FilterAndCombine */
 /* This is a decoder function that takes the decimated
    length len/2 input low-pass and
    high-pass signals and creates a reconstructed fullband
    output signal of length len. WebRtcIsacfix_FilterAndCombine
    is the sibling function of WebRtcIsacfix_SplitAndFilter */
 /* INPUTS:
    inLP: a length len/2 array of input low-pass
    samples.
    inHP: a length len/2 array of input high-pass
    samples.
    postfiltdata: input data structure containing the filterbank
    states from the previous decoding iteration.
    OUTPUTS:
    Out: a length len array of output reconstructed
    samples (fullband) based on the input low-pass and
    high-pass signals.
    postfiltdata: the input data structure containing the filterbank
    states is updated for the next decoding iteration */
 void WebRtcIsacfix_FilterAndCombine2(WebRtc_Word16 *tempin_ch1,
                                      WebRtc_Word16 *tempin_ch2,
                                      WebRtc_Word16 *out16,
                                      PostFiltBankstr *postfiltdata,
                                      WebRtc_Word16 len)
 {
   int k;
   WebRtc_Word16 in[FRAMESAMPLES];

   /* all-pass filter the new upper channel signal. HOWEVER, use the all-pass filter factors
      that were used as a lower channel at the encoding side.  So at the decoder, the
      corresponding all-pass filter factors for each channel are swapped.*/

   AllpassFilter2FixDec16(tempin_ch1, WebRtcIsacfix_kLowerApFactorsQ15,(WebRtc_Word16) (len/2), NUMBEROFCHANNELAPSECTIONS,postfiltdata->STATE_0_UPPER_fix);

   /* Now, all-pass filter the new lower channel signal. But since all-pass filter factors
      at the decoder are swapped from the ones at the encoder, the 'upper' channel
      all-pass filter factors (kUpperApFactors) are used to filter this new lower channel signal */

   AllpassFilter2FixDec16(tempin_ch2, WebRtcIsacfix_kUpperApFactorsQ15, (WebRtc_Word16) (len/2), NUMBEROFCHANNELAPSECTIONS,postfiltdata->STATE_0_LOWER_fix);

   /* Merge outputs to form the full length output signal.*/
   for (k=0;k<len/2;k++) {
     in[WEBRTC_SPL_MUL_16_16(2, k)]=tempin_ch2[k];
     in[WEBRTC_SPL_MUL_16_16(2, k)+1]=tempin_ch1[k];
   }

   /* High pass filter */
   HighpassFilterFixDec32(in, len, WebRtcIsacfix_kHPStCoeffOut1Q30, postfiltdata->HPstates1_fix);
   HighpassFilterFixDec32(in, len, WebRtcIsacfix_kHPStCoeffOut2Q30, postfiltdata->HPstates2_fix);

   for (k=0;k<len;k++) {
     out16[k] = in[k];
   }
 }

 #endif
	/*
	* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
	*
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	/*
	* filterbanks.c
	*
	* This file contains function
	* WebRtcIsacfix_SplitAndFilter, and WebRtcIsacfix_FilterAndCombine
	* which implement filterbanks that produce decimated lowpass and
	* highpass versions of a signal, and performs reconstruction.
	*
	*/

	#include "codec.h"
	#include "filterbank_tables.h"
	#include "settings.h"


	static void AllpassFilter2FixDec16(WebRtc_Word16 *InOut16, //Q0
	const WebRtc_Word16 *APSectionFactors, //Q15
	WebRtc_Word16 lengthInOut,
	WebRtc_Word16 NumberOfSections,
	WebRtc_Word32 *FilterState) //Q16
	{
	int n, j;
	WebRtc_Word32 a, b;

	for (j=0; j<NumberOfSections; j++) {
	for (n=0;n<lengthInOut;n++) {


	a = WEBRTC_SPL_MUL_16_16(APSectionFactors[j], InOut16[n]); //Q15*Q0=Q15
	a = WEBRTC_SPL_LSHIFT_W32(a, 1); // Q15 -> Q16
	b = WEBRTC_SPL_ADD_SAT_W32(a, FilterState[j]); //Q16+Q16=Q16
	a = WEBRTC_SPL_MUL_16_16_RSFT(-APSectionFactors[j], (WebRtc_Word16) WEBRTC_SPL_RSHIFT_W32(b, 16), 0); //Q15*Q0=Q15
	FilterState[j] = WEBRTC_SPL_ADD_SAT_W32(WEBRTC_SPL_LSHIFT_W32(a,1), WEBRTC_SPL_LSHIFT_W32((WebRtc_UWord32)InOut16[n],16)); // Q15<<1 + Q0<<16 = Q16 + Q16 = Q16
	InOut16[n] = (WebRtc_Word16) WEBRTC_SPL_RSHIFT_W32(b, 16); //Save as Q0

	}
	}

	}


	static void HighpassFilterFixDec32(
	WebRtc_Word16 io, / Q0:input Q0: Output */
	WebRtc_Word16 len, /* length of input, Input */
	const WebRtc_Word16 coeff, / Coeff: [Q30hi Q30lo Q30hi Q30lo Q35hi Q35lo Q35hi Q35lo] */
	WebRtc_Word32 state) / Q4:filter state Input/Output */
	{
	int k;
	WebRtc_Word32 a, b, c, in;



	for (k=0; k<len; k++) {
	in = (WebRtc_Word32)io[k];
	/* Q35 * Q4 = Q39 ; shift 32 bit => Q7 */
	a = WEBRTC_SPL_MUL_32_32_RSFT32(coeff[22], coeff[22+1], state[0]);
	b = WEBRTC_SPL_MUL_32_32_RSFT32(coeff[23], coeff[23+1], state[1]);

	c = ((WebRtc_Word32)in) + WEBRTC_SPL_RSHIFT_W32(a+b, 7); // Q0
	//c = WEBRTC_SPL_RSHIFT_W32(c, 1); // Q-1
	io[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(c); // Write output as Q0

	/* Q30 * Q4 = Q34 ; shift 32 bit => Q2 */
	a = WEBRTC_SPL_MUL_32_32_RSFT32(coeff[20], coeff[20+1], state[0]);
	b = WEBRTC_SPL_MUL_32_32_RSFT32(coeff[21], coeff[21+1], state[1]);

	c = WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)in, 2) - a - b; // New state in Q2
	c= (WebRtc_Word32)WEBRTC_SPL_SAT((WebRtc_Word32)536870911, c, (WebRtc_Word32)-536870912); // Check for wrap-around

	state[1] = state[0];
	state[0] = WEBRTC_SPL_LSHIFT_W32(c, 2); // Write state as Q4

	}
	}


	void WebRtcIsacfix_SplitAndFilter1(WebRtc_Word16 *pin,
	WebRtc_Word16 *LP16,
	WebRtc_Word16 *HP16,
	PreFiltBankstr *prefiltdata)
	{
	/* Function WebRtcIsacfix_SplitAndFilter */
	/* This function creates low-pass and high-pass decimated versions of part of
	the input signal, and part of the signal in the input 'lookahead buffer'. */

	int k;

	WebRtc_Word16 tempin_ch1[FRAMESAMPLES/2 + QLOOKAHEAD];
	WebRtc_Word16 tempin_ch2[FRAMESAMPLES/2 + QLOOKAHEAD];
	WebRtc_Word32 tmpState[WEBRTC_SPL_MUL_16_16(2,(QORDER-1))]; /* 4 */


	/* High pass filter */
	HighpassFilterFixDec32(pin, FRAMESAMPLES, WebRtcIsacfix_kHpStCoeffInQ30, prefiltdata->HPstates_fix);


	/* First Channel */
	for (k=0;k<FRAMESAMPLES/2;k++) {
	tempin_ch1[QLOOKAHEAD + k] = pin[1+WEBRTC_SPL_MUL_16_16(2, k)];
	}
	for (k=0;k<QLOOKAHEAD;k++) {
	tempin_ch1[k]=prefiltdata->INLABUF1_fix[k];
	prefiltdata->INLABUF1_fix[k]=pin[FRAMESAMPLES+1-WEBRTC_SPL_MUL_16_16(2, QLOOKAHEAD)+WEBRTC_SPL_MUL_16_16(2, k)];
	}

	/* Second Channel. This is exactly like the first channel, except that the
	even samples are now filtered instead (lower channel). */
	for (k=0;k<FRAMESAMPLES/2;k++) {
	tempin_ch2[QLOOKAHEAD+k] = pin[WEBRTC_SPL_MUL_16_16(2, k)];
	}
	for (k=0;k<QLOOKAHEAD;k++) {
	tempin_ch2[k]=prefiltdata->INLABUF2_fix[k];
	prefiltdata->INLABUF2_fix[k]=pin[FRAMESAMPLES-WEBRTC_SPL_MUL_16_16(2, QLOOKAHEAD)+WEBRTC_SPL_MUL_16_16(2, k)];
	}


	/obtain polyphase components by forward all-pass filtering through each channel /
	/* The all pass filtering automatically updates the filter states which are exported in the
	prefiltdata structure */
	AllpassFilter2FixDec16(tempin_ch1,WebRtcIsacfix_kUpperApFactorsQ15, FRAMESAMPLES/2 , NUMBEROFCHANNELAPSECTIONS, prefiltdata->INSTAT1_fix);
	AllpassFilter2FixDec16(tempin_ch2,WebRtcIsacfix_kLowerApFactorsQ15, FRAMESAMPLES/2 , NUMBEROFCHANNELAPSECTIONS, prefiltdata->INSTAT2_fix);

	for (k=0;k<WEBRTC_SPL_MUL_16_16(2, (QORDER-1));k++)
	tmpState[k] = prefiltdata->INSTAT1_fix[k];
	AllpassFilter2FixDec16(tempin_ch1 + FRAMESAMPLES/2,WebRtcIsacfix_kUpperApFactorsQ15, QLOOKAHEAD , NUMBEROFCHANNELAPSECTIONS, tmpState);
	for (k=0;k<WEBRTC_SPL_MUL_16_16(2, (QORDER-1));k++)
	tmpState[k] = prefiltdata->INSTAT2_fix[k];
	AllpassFilter2FixDec16(tempin_ch2 + FRAMESAMPLES/2,WebRtcIsacfix_kLowerApFactorsQ15, QLOOKAHEAD , NUMBEROFCHANNELAPSECTIONS, tmpState);


	/* Now Construct low-pass and high-pass signals as combinations of polyphase components */
	for (k=0; k<FRAMESAMPLES/2 + QLOOKAHEAD; k++) {
	WebRtc_Word32 tmp1, tmp2, tmp3;
	tmp1 = (WebRtc_Word32)tempin_ch1[k]; // Q0 -> Q0
	tmp2 = (WebRtc_Word32)tempin_ch2[k]; // Q0 -> Q0
	tmp3 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W32((tmp1 + tmp2), 1);/* low pass signal*/
	LP16[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp3); /low pass /
	tmp3 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W32((tmp1 - tmp2), 1);/* high pass signal*/
	HP16[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp3); /high pass /
	}

	}/end of WebRtcIsacfix_SplitAndFilter /


	#ifdef WEBRTC_ISAC_FIX_NB_CALLS_ENABLED

	/* Without lookahead */
	void WebRtcIsacfix_SplitAndFilter2(WebRtc_Word16 *pin,
	WebRtc_Word16 *LP16,
	WebRtc_Word16 *HP16,
	PreFiltBankstr *prefiltdata)
	{
	/* Function WebRtcIsacfix_SplitAndFilter2 */
	/* This function creates low-pass and high-pass decimated versions of part of
	the input signal. */

	int k;

	WebRtc_Word16 tempin_ch1[FRAMESAMPLES/2];
	WebRtc_Word16 tempin_ch2[FRAMESAMPLES/2];


	/* High pass filter */
	HighpassFilterFixDec32(pin, FRAMESAMPLES, WebRtcIsacfix_kHpStCoeffInQ30, prefiltdata->HPstates_fix);


	/* First Channel */
	for (k=0;k<FRAMESAMPLES/2;k++) {
	tempin_ch1[k] = pin[1+WEBRTC_SPL_MUL_16_16(2, k)];
	}

	/* Second Channel. This is exactly like the first channel, except that the
	even samples are now filtered instead (lower channel). */
	for (k=0;k<FRAMESAMPLES/2;k++) {
	tempin_ch2[k] = pin[WEBRTC_SPL_MUL_16_16(2, k)];
	}


	/obtain polyphase components by forward all-pass filtering through each channel /
	/* The all pass filtering automatically updates the filter states which are exported in the
	prefiltdata structure */
	AllpassFilter2FixDec16(tempin_ch1,WebRtcIsacfix_kUpperApFactorsQ15, FRAMESAMPLES/2 , NUMBEROFCHANNELAPSECTIONS, prefiltdata->INSTAT1_fix);
	AllpassFilter2FixDec16(tempin_ch2,WebRtcIsacfix_kLowerApFactorsQ15, FRAMESAMPLES/2 , NUMBEROFCHANNELAPSECTIONS, prefiltdata->INSTAT2_fix);


	/* Now Construct low-pass and high-pass signals as combinations of polyphase components */
	for (k=0; k<FRAMESAMPLES/2; k++) {
	WebRtc_Word32 tmp1, tmp2, tmp3;
	tmp1 = (WebRtc_Word32)tempin_ch1[k]; // Q0 -> Q0
	tmp2 = (WebRtc_Word32)tempin_ch2[k]; // Q0 -> Q0
	tmp3 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W32((tmp1 + tmp2), 1);/* low pass signal*/
	LP16[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp3); /low pass /
	tmp3 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W32((tmp1 - tmp2), 1);/* high pass signal*/
	HP16[k] = (WebRtc_Word16)WebRtcSpl_SatW32ToW16(tmp3); /high pass /
	}

	}/end of WebRtcIsacfix_SplitAndFilter /

	#endif



	//////////////////////////////////////////////////////////
	////////// Combining
	/* Function WebRtcIsacfix_FilterAndCombine */
	/* This is a decoder function that takes the decimated
	length FRAMESAMPLES/2 input low-pass and
	high-pass signals and creates a reconstructed fullband
	output signal of length FRAMESAMPLES. WebRtcIsacfix_FilterAndCombine
	is the sibling function of WebRtcIsacfix_SplitAndFilter */
	/* INPUTS:
	inLP: a length FRAMESAMPLES/2 array of input low-pass
	samples.
	inHP: a length FRAMESAMPLES/2 array of input high-pass
	samples.
	postfiltdata: input data structure containing the filterbank
	states from the previous decoding iteration.
	OUTPUTS:
	Out: a length FRAMESAMPLES array of output reconstructed
	samples (fullband) based on the input low-pass and
	high-pass signals.
	postfiltdata: the input data structure containing the filterbank
	states is updated for the next decoding iteration */
	void WebRtcIsacfix_FilterAndCombine1(WebRtc_Word16 *tempin_ch1,
	WebRtc_Word16 *tempin_ch2,
	WebRtc_Word16 *out16,
	PostFiltBankstr *postfiltdata)
	{
	int k;
	WebRtc_Word16 in[FRAMESAMPLES];

	/* all-pass filter the new upper channel signal. HOWEVER, use the all-pass filter factors
	that were used as a lower channel at the encoding side. So at the decoder, the
	corresponding all-pass filter factors for each channel are swapped.*/

	AllpassFilter2FixDec16(tempin_ch1, WebRtcIsacfix_kLowerApFactorsQ15, FRAMESAMPLES/2, NUMBEROFCHANNELAPSECTIONS,postfiltdata->STATE_0_UPPER_fix);

	/* Now, all-pass filter the new lower channel signal. But since all-pass filter factors
	at the decoder are swapped from the ones at the encoder, the 'upper' channel
	all-pass filter factors (kUpperApFactors) are used to filter this new lower channel signal */

	AllpassFilter2FixDec16(tempin_ch2, WebRtcIsacfix_kUpperApFactorsQ15, FRAMESAMPLES/2, NUMBEROFCHANNELAPSECTIONS,postfiltdata->STATE_0_LOWER_fix);

	/* Merge outputs to form the full length output signal.*/
	for (k=0;k<FRAMESAMPLES/2;k++) {
	in[WEBRTC_SPL_MUL_16_16(2, k)]=tempin_ch2[k];
	in[WEBRTC_SPL_MUL_16_16(2, k)+1]=tempin_ch1[k];
	}

	/* High pass filter */
	HighpassFilterFixDec32(in, FRAMESAMPLES, WebRtcIsacfix_kHPStCoeffOut1Q30, postfiltdata->HPstates1_fix);
	HighpassFilterFixDec32(in, FRAMESAMPLES, WebRtcIsacfix_kHPStCoeffOut2Q30, postfiltdata->HPstates2_fix);

	for (k=0;k<FRAMESAMPLES;k++) {
	out16[k] = in[k];
	}
	}


	#ifdef WEBRTC_ISAC_FIX_NB_CALLS_ENABLED
	/* Function WebRtcIsacfix_FilterAndCombine */
	/* This is a decoder function that takes the decimated
	length len/2 input low-pass and
	high-pass signals and creates a reconstructed fullband
	output signal of length len. WebRtcIsacfix_FilterAndCombine
	is the sibling function of WebRtcIsacfix_SplitAndFilter */
	/* INPUTS:
	inLP: a length len/2 array of input low-pass
	samples.
	inHP: a length len/2 array of input high-pass
	samples.
	postfiltdata: input data structure containing the filterbank
	states from the previous decoding iteration.
	OUTPUTS:
	Out: a length len array of output reconstructed
	samples (fullband) based on the input low-pass and
	high-pass signals.
	postfiltdata: the input data structure containing the filterbank
	states is updated for the next decoding iteration */
	void WebRtcIsacfix_FilterAndCombine2(WebRtc_Word16 *tempin_ch1,
	WebRtc_Word16 *tempin_ch2,
	WebRtc_Word16 *out16,
	PostFiltBankstr *postfiltdata,
	WebRtc_Word16 len)
	{
	int k;
	WebRtc_Word16 in[FRAMESAMPLES];

	/* all-pass filter the new upper channel signal. HOWEVER, use the all-pass filter factors
	that were used as a lower channel at the encoding side. So at the decoder, the
	corresponding all-pass filter factors for each channel are swapped.*/

	AllpassFilter2FixDec16(tempin_ch1, WebRtcIsacfix_kLowerApFactorsQ15,(WebRtc_Word16) (len/2), NUMBEROFCHANNELAPSECTIONS,postfiltdata->STATE_0_UPPER_fix);

	/* Now, all-pass filter the new lower channel signal. But since all-pass filter factors
	at the decoder are swapped from the ones at the encoder, the 'upper' channel
	all-pass filter factors (kUpperApFactors) are used to filter this new lower channel signal */

	AllpassFilter2FixDec16(tempin_ch2, WebRtcIsacfix_kUpperApFactorsQ15, (WebRtc_Word16) (len/2), NUMBEROFCHANNELAPSECTIONS,postfiltdata->STATE_0_LOWER_fix);

	/* Merge outputs to form the full length output signal.*/
	for (k=0;k<len/2;k++) {
	in[WEBRTC_SPL_MUL_16_16(2, k)]=tempin_ch2[k];
	in[WEBRTC_SPL_MUL_16_16(2, k)+1]=tempin_ch1[k];
	}

	/* High pass filter */
	HighpassFilterFixDec32(in, len, WebRtcIsacfix_kHPStCoeffOut1Q30, postfiltdata->HPstates1_fix);
	HighpassFilterFixDec32(in, len, WebRtcIsacfix_kHPStCoeffOut2Q30, postfiltdata->HPstates2_fix);

	for (k=0;k<len;k++) {
	out16[k] = in[k];
	}
	}

	#endif