| /* |
| * 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 "modules/audio_coding/codecs/ilbc/defines.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 |
