1 /* 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 /****************************************************************** 12 13 iLBC Speech Coder ANSI-C Source Code 14 15 WebRtcIlbcfix_GetLspPoly.h 16 17 ******************************************************************/ 18 19 #ifndef WEBRTC_MODULES_AUDIO_CODING_CODECS_ILBC_MAIN_SOURCE_GET_LSP_POLY_H_ 20 #define WEBRTC_MODULES_AUDIO_CODING_CODECS_ILBC_MAIN_SOURCE_GET_LSP_POLY_H_ 21 22 #include "defines.h" 23 24 /*----------------------------------------------------------------* 25 * Construct the polynomials F1(z) and F2(z) from the LSP 26 * (Computations are done in Q24) 27 * 28 * The expansion is performed using the following recursion: 29 * 30 * f[0] = 1; 31 * tmp = -2.0 * lsp[0]; 32 * f[1] = tmp; 33 * for (i=2; i<=5; i++) { 34 * b = -2.0 * lsp[2*i-2]; 35 * f[i] = tmp*f[i-1] + 2.0*f[i-2]; 36 * for (j=i; j>=2; j--) { 37 * f[j] = f[j] + tmp*f[j-1] + f[j-2]; 38 * } 39 * f[i] = f[i] + tmp; 40 * } 41 *---------------------------------------------------------------*/ 42 43 void WebRtcIlbcfix_GetLspPoly( 44 int16_t *lsp, /* (i) LSP in Q15 */ 45 int32_t *f); /* (o) polonymial in Q24 */ 46 47 #endif 48
