| /* ------------------------------------------------------------------ |
| * Copyright (C) 1998-2009 PacketVideo |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either |
| * express or implied. |
| * See the License for the specific language governing permissions |
| * and limitations under the License. |
| * ------------------------------------------------------------------- |
| */ |
| /**************************************************************************************** |
| Portions of this file are derived from the following 3GPP standard: |
| |
| 3GPP TS 26.173 |
| ANSI-C code for the Adaptive Multi-Rate - Wideband (AMR-WB) speech codec |
| Available from http://www.3gpp.org |
| |
| (C) 2007, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC) |
| Permission to distribute, modify and use this file under the standard license |
| terms listed above has been obtained from the copyright holder. |
| ****************************************************************************************/ |
| /* |
| ------------------------------------------------------------------------------ |
| |
| |
| |
| Filename: highpass_400Hz_at_12k8.cpp |
| |
| Date: 05/08/2004 |
| |
| ------------------------------------------------------------------------------ |
| REVISION HISTORY |
| |
| |
| Description: |
| |
| ------------------------------------------------------------------------------ |
| INPUT AND OUTPUT DEFINITIONS |
| |
| int16 signal[], input signal / output is divided by 16 |
| int16 lg, lenght of signal |
| int16 mem[] filter memory [6] |
| |
| |
| ------------------------------------------------------------------------------ |
| FUNCTION DESCRIPTION |
| |
| 2nd order high pass filter with cut off frequency at 400 Hz. |
| Designed with cheby2 function in MATLAB. |
| Optimized for fixed-point to get the following frequency response: |
| |
| frequency: 0Hz 100Hz 200Hz 300Hz 400Hz 630Hz 1.5kHz 3kHz |
| dB loss: -infdB -30dB -20dB -10dB -3dB +6dB +1dB 0dB |
| |
| Algorithm: |
| |
| y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2] |
| + a[1]*y[i-1] + a[2]*y[i-2]; |
| |
| int16 b[3] = {3660, -7320, 3660}; in Q12 |
| int16 a[3] = {4096, 7320, -3540}; in Q12 |
| |
| float --> b[3] = {0.893554687, -1.787109375, 0.893554687}; |
| a[3] = {1.000000000, 1.787109375, -0.864257812}; |
| |
| |
| ------------------------------------------------------------------------------ |
| REQUIREMENTS |
| |
| |
| ------------------------------------------------------------------------------ |
| REFERENCES |
| |
| ------------------------------------------------------------------------------ |
| PSEUDO-CODE |
| |
| ------------------------------------------------------------------------------ |
| */ |
| |
| |
| /*---------------------------------------------------------------------------- |
| ; INCLUDES |
| ----------------------------------------------------------------------------*/ |
| |
| #include "pv_amr_wb_type_defs.h" |
| #include "pvamrwbdecoder_basic_op.h" |
| #include "pvamrwb_math_op.h" |
| #include "pvamrwbdecoder_acelp.h" |
| |
| /*---------------------------------------------------------------------------- |
| ; MACROS |
| ; Define module specific macros here |
| ----------------------------------------------------------------------------*/ |
| |
| |
| /*---------------------------------------------------------------------------- |
| ; DEFINES |
| ; Include all pre-processor statements here. Include conditional |
| ; compile variables also. |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; LOCAL FUNCTION DEFINITIONS |
| ; Function Prototype declaration |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; LOCAL STORE/BUFFER/POINTER DEFINITIONS |
| ; Variable declaration - defined here and used outside this module |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; EXTERNAL FUNCTION REFERENCES |
| ; Declare functions defined elsewhere and referenced in this module |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES |
| ; Declare variables used in this module but defined elsewhere |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; FUNCTION CODE |
| ----------------------------------------------------------------------------*/ |
| /* Initialization of static values */ |
| |
| void highpass_400Hz_at_12k8_init(int16 mem[]) |
| { |
| pv_memset((void *)mem, 0, 6*sizeof(*mem)); |
| } |
| |
| /*---------------------------------------------------------------------------- |
| ; FUNCTION CODE |
| ----------------------------------------------------------------------------*/ |
| |
| void highpass_400Hz_at_12k8( |
| int16 signal[], /* input signal / output is divided by 16 */ |
| int16 lg, /* lenght of signal */ |
| int16 mem[] /* filter memory [6] */ |
| ) |
| { |
| int16 i, x2; |
| int16 y2_hi, y2_lo, y1_hi, y1_lo, x0, x1; |
| int32 L_tmp1; |
| int32 L_tmp2; |
| |
| y2_hi = mem[0]; |
| y2_lo = mem[1]; |
| y1_hi = mem[2]; |
| y1_lo = mem[3]; |
| x0 = mem[4]; |
| x1 = mem[5]; |
| |
| for (i = 0; i < lg; i++) |
| { |
| |
| /* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[0]*x[i-2] */ |
| /* + a[0]*y[i-1] + a[1] * y[i-2]; */ |
| |
| L_tmp1 = fxp_mac_16by16(y1_lo, 29280, 8192L); |
| L_tmp2 = fxp_mul_16by16(y1_hi, 29280); |
| L_tmp1 = fxp_mac_16by16(y2_lo, -14160, L_tmp1); |
| L_tmp2 = fxp_mac_16by16(y2_hi, -14160, L_tmp2); |
| x2 = x1; |
| x1 = x0; |
| x0 = signal[i]; |
| L_tmp2 = fxp_mac_16by16(x2, 915, L_tmp2); |
| L_tmp2 = fxp_mac_16by16(x1, -1830, L_tmp2); |
| L_tmp2 = fxp_mac_16by16(x0, 915, L_tmp2); |
| |
| L_tmp1 = (L_tmp1 >> 13) + (L_tmp2 << 2); /* coeff Q12 --> Q13 */ |
| |
| y2_hi = y1_hi; |
| y2_lo = y1_lo; |
| /* signal is divided by 16 to avoid overflow in energy computation */ |
| signal[i] = (int16)((L_tmp1 + 0x00008000) >> 16); |
| |
| y1_hi = (int16)(L_tmp1 >> 16); |
| y1_lo = (int16)((L_tmp1 - (y1_hi << 16)) >> 1); |
| |
| |
| } |
| |
| |
| mem[0] = y2_hi; |
| mem[1] = y2_lo; |
| mem[2] = y1_hi; |
| mem[3] = y1_lo; |
| mem[4] = x0; |
| mem[5] = x1; |
| |
| } |
| |
| |