| /* | |
| * 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. | |
| */ | |
| /****************************************************************** | |
| iLBC Speech Coder ANSI-C Source Code | |
| WebRtcIlbcfix_GetLspPoly.h | |
| ******************************************************************/ | |
| #ifndef MODULES_AUDIO_CODING_CODECS_ILBC_MAIN_SOURCE_GET_LSP_POLY_H_ | |
| #define MODULES_AUDIO_CODING_CODECS_ILBC_MAIN_SOURCE_GET_LSP_POLY_H_ | |
| #include <stdint.h> | |
| /*----------------------------------------------------------------* | |
| * Construct the polynomials F1(z) and F2(z) from the LSP | |
| * (Computations are done in Q24) | |
| * | |
| * The expansion is performed using the following recursion: | |
| * | |
| * f[0] = 1; | |
| * tmp = -2.0 * lsp[0]; | |
| * f[1] = tmp; | |
| * for (i=2; i<=5; i++) { | |
| * b = -2.0 * lsp[2*i-2]; | |
| * f[i] = tmp*f[i-1] + 2.0*f[i-2]; | |
| * for (j=i; j>=2; j--) { | |
| * f[j] = f[j] + tmp*f[j-1] + f[j-2]; | |
| * } | |
| * f[i] = f[i] + tmp; | |
| * } | |
| *---------------------------------------------------------------*/ | |
| void WebRtcIlbcfix_GetLspPoly(int16_t* lsp, /* (i) LSP in Q15 */ | |
| int32_t* f); /* (o) polonymial in Q24 */ | |
| #endif |