/* ------------------------------------------------------------------ * 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 26.073 ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec Available from http://www.3gpp.org (C) 2004, 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. ****************************************************************************************/ /* ------------------------------------------------------------------------------ Pathname: ./audio/gsm-amr/c/src/post_pro.c Functions: Post_Process_reset Post_Process Date: 04/03/2000 ------------------------------------------------------------------------------ REVISION HISTORY Description: Updated template used to PV coding template. First attempt at optimizing C code. Description: Deleted variables listed in the Local Stores Needed/Modified sections. Optimized the "else" portion of the first "if" statement in Post_Process function. Description: Made grouping more explicit in the calculation of signal[i] << 1 in the Post_Process function. Description: Added setting of Overflow flag in inlined code. Description: Synchronized file with UMTS version 3.2.0. Updated coding template. Removed unnecessary include files. Description: Replaced basic_op.h with the header file of the math functions used in the file. Description: Made the following changes per comments from Phase 2/3 review: 1. Updated copyright year. 2. Fixed typecasting issue with TI C compiler. 3. Used short-hand notation for math operations, e.g., "+=", in the code. Description: Removed the functions post_pro_init and post_pro_exit. The post_pro related structure is no longer dynamically allocated. Description: Added pOverflow as a passed in variable as per changes needed for the EPOC release. Description: Optimized file to reduce clock cycle usage. Updated copyright year and removed unused files in Include section. Description: Replaced OSCL mem type functions and eliminated include files that now are chosen by OSCL definitions Description: Replaced "int" and/or "char" with OSCL defined types. Description: Changed round function name to pv_round to avoid conflict with round function in C standard library. Description: ------------------------------------------------------------------------------ MODULE DESCRIPTION This file contains the function that performs post-processing on the output speech. Post-processing include filtering the output speech through a second order high pass filter with cutoff frequency of 60 Hz, and up-scaling the output speech by a factor of 2. In addition to the post-processing function itself, a post-processing initialization function, post-processing reset function, and post-processing exit function are also included in this file. ------------------------------------------------------------------------------ */ /*---------------------------------------------------------------------------- ; INCLUDES ----------------------------------------------------------------------------*/ #include "post_pro.h" #include "typedef.h" #include "basic_op.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 VARIABLE DEFINITIONS ; Variable declaration - defined here and used outside this module ----------------------------------------------------------------------------*/ /* filter coefficients (fc = 60 Hz) */ static const Word16 b[3] = {7699, -15398, 7699}; static const Word16 a[3] = {8192, 15836, -7667}; /* ------------------------------------------------------------------------------ FUNCTION NAME: Post_Process_reset ------------------------------------------------------------------------------ INPUT AND OUTPUT DEFINITIONS Inputs: state = pointer to a structure of type Post_ProcessState Outputs: structure pointed to by state will have all its fields initialized to zero Returns: return_value = 0, if reset was successful; -1, otherwise (int) Global Variables Used: None Local Variables Needed: None ------------------------------------------------------------------------------ FUNCTION DESCRIPTION This function initializes state memory to zero. ------------------------------------------------------------------------------ REQUIREMENTS None ------------------------------------------------------------------------------ REFERENCES post_pro.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 ------------------------------------------------------------------------------ PSEUDO-CODE int Post_Process_reset (Post_ProcessState *state) { if (state == (Post_ProcessState *) NULL){ fprint(stderr, "Post_Process_reset: invalid parameter\n"); return -1; } state->y2_hi = 0; state->y2_lo = 0; state->y1_hi = 0; state->y1_lo = 0; state->x0 = 0; state->x1 = 0; return 0; } ------------------------------------------------------------------------------ RESOURCES USED [optional] When the code is written for a specific target processor the the resources used should be documented below. HEAP MEMORY USED: x bytes STACK MEMORY USED: x bytes CLOCK CYCLES: (cycle count equation for this function) + (variable used to represent cycle count for each subroutine called) where: (cycle count variable) = cycle count for [subroutine name] ------------------------------------------------------------------------------ CAUTION [optional] [State any special notes, constraints or cautions for users of this function] ------------------------------------------------------------------------------ */ Word16 Post_Process_reset(Post_ProcessState *state) { if (state == (Post_ProcessState *) NULL) { /* fprint(stderr, "Post_Process_reset: invalid parameter\n"); */ return(-1); } state->y2_hi = 0; state->y2_lo = 0; state->y1_hi = 0; state->y1_lo = 0; state->x0 = 0; state->x1 = 0; return(0); } /****************************************************************************/ /* ------------------------------------------------------------------------------ FUNCTION NAME: Post_Process ------------------------------------------------------------------------------ INPUT AND OUTPUT DEFINITIONS Inputs: st = pointer to a structure of type Post_ProcessState signal = buffer containing the input signal (Word16) lg = length of the input signal (Word16) pOverflow = pointer to overflow indicator of type Flag Outputs: structure pointed to by st contains new filter input and output values signal buffer contains the HP filtered and up-scaled input signal pOverflow points to 1 if overflow occurs in the math functions called else it points to 0. Returns: return_value = 0 (int) Global Variables Used: a = buffer containing filter coefficients b = buffer containing filter coefficients Local Variables Needed: None ------------------------------------------------------------------------------ FUNCTION DESCRIPTION This function performs post-processing on the output speech signal. First, the output speech goes through a second order high pass filter with a cutoff frequency of 60 Hz. Then, the filtered output speech is multiplied by a factor of 2. The algorithm implemented follows the following difference equation: y[i] = b[0]*x[i]*2 + b[1]*x[i-1]*2 + b[2]*x[i-2]*2 + a[1]*y[i-1] + a[2]*y[i-2]; ------------------------------------------------------------------------------ REQUIREMENTS None ------------------------------------------------------------------------------ REFERENCES post_pro.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 ------------------------------------------------------------------------------ PSEUDO-CODE int Post_Process ( Post_ProcessState *st, //i/o : post process state Word16 signal[], //i/o : signal Word16 lg //i : length of signal ) { Word16 i, x2; Word32 L_tmp; for (i = 0; i < lg; i++) { x2 = st->x1; st->x1 = st->x0; st->x0 = signal[i]; // y[i] = b[0]*x[i]*2 + b[1]*x[i-1]*2 + b140[2]*x[i-2]/2 // + a[1]*y[i-1] + a[2] * y[i-2]; L_tmp = Mpy_32_16 (st->y1_hi, st->y1_lo, a[1]); L_tmp = L_add (L_tmp, Mpy_32_16 (st->y2_hi, st->y2_lo, a[2])); L_tmp = L_mac (L_tmp, st->x0, b[0]); L_tmp = L_mac (L_tmp, st->x1, b[1]); L_tmp = L_mac (L_tmp, x2, b[2]); L_tmp = L_shl (L_tmp, 2); //Multiplication by two of output speech with saturation. signal[i] = pv_round(L_shl(L_tmp, 1)); st->y2_hi = st->y1_hi; st->y2_lo = st->y1_lo; L_Extract (L_tmp, &st->y1_hi, &st->y1_lo); } return 0; } ------------------------------------------------------------------------------ RESOURCES USED [optional] When the code is written for a specific target processor the the resources used should be documented below. HEAP MEMORY USED: x bytes STACK MEMORY USED: x bytes CLOCK CYCLES: (cycle count equation for this function) + (variable used to represent cycle count for each subroutine called) where: (cycle count variable) = cycle count for [subroutine name] ------------------------------------------------------------------------------ CAUTION [optional] [State any special notes, constraints or cautions for users of this function] ------------------------------------------------------------------------------ */ void Post_Process( Post_ProcessState *st, /* i/o : post process state */ Word16 signal[], /* i/o : signal */ Word16 lg, /* i : length of signal */ Flag *pOverflow ) { Word16 i, x2; Word32 L_tmp; Word16 *p_signal; Word16 c_a1 = a[1]; Word16 c_a2 = a[2]; Word16 c_b0 = b[0]; Word16 c_b1 = b[1]; Word16 c_b2 = b[2]; p_signal = &signal[0]; for (i = 0; i < lg; i++) { x2 = st->x1; st->x1 = st->x0; st->x0 = *(p_signal); /* y[i] = b[0]*x[i]*2 + b[1]*x[i-1]*2 + b140[2]*x[i-2]/2 */ /* + a[1]*y[i-1] + a[2] * y[i-2]; */ L_tmp = ((Word32) st->y1_hi) * c_a1; L_tmp += (((Word32) st->y1_lo) * c_a1) >> 15; L_tmp += ((Word32) st->y2_hi) * c_a2; L_tmp += (((Word32) st->y2_lo) * c_a2) >> 15; L_tmp += ((Word32) st->x0) * c_b0; L_tmp += ((Word32) st->x1) * c_b1; L_tmp += ((Word32) x2) * c_b2; L_tmp = L_shl(L_tmp, 3, pOverflow); /* Multiplication by two of output speech with saturation. */ *(p_signal++) = pv_round(L_shl(L_tmp, 1, pOverflow), pOverflow); st->y2_hi = st->y1_hi; st->y2_lo = st->y1_lo; st->y1_hi = (Word16)(L_tmp >> 16); st->y1_lo = (Word16)((L_tmp >> 1) - ((Word32) st->y1_hi << 15)); } return; }