FreeCalypso > hg > gsm-codec-lib
view libtwamr/int_lpc.h @ 482:5e2d849a4fbc
doc/Calypso-TCH-downlink: grammar fix
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Mon, 20 May 2024 01:24:22 +0000 |
parents | 32bc48faec4b |
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/* ******************************************************************************** * * GSM AMR-NB speech codec R98 Version 7.6.0 December 12, 2001 * R99 Version 3.3.0 * REL-4 Version 4.1.0 * ******************************************************************************** * * File : int_lpc.h * Purpose : Interpolates the LSPs and converts to LPC parameters * ******************************************************************************** */ #ifndef int_lpc_h #define int_lpc_h "$Id $" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "typedef.h" /* ******************************************************************************** * DEFINITION OF DATA TYPES ******************************************************************************** */ /* ******************************************************************************** * DECLARATION OF PROTOTYPES ******************************************************************************** */ /* ************************************************************************** * * Function : Int_lpc_1and3 * Purpose : Interpolates the LSPs and converts to LPC parameters * to get a different LP filter in each subframe. * Description : The 20 ms speech frame is divided into 4 subframes. * The LSPs are quantized and transmitted at the 2nd and * 4th subframes (twice per frame) and interpolated at the * 1st and 3rd subframe. * * |------|------|------|------| * sf1 sf2 sf3 sf4 * F0 Fm F1 * * sf1: 1/2 Fm + 1/2 F0 sf3: 1/2 F1 + 1/2 Fm * sf2: Fm sf4: F1 * Returns : void * ************************************************************************** */ void Int_lpc_1and3 ( Word16 lsp_old[], /* i : LSP vector at the 4th subfr. of past frame (M) */ Word16 lsp_mid[], /* i : LSP vector at the 2nd subfr. of present frame (M) */ Word16 lsp_new[], /* i : LSP vector at the 4th subfr. of present frame (M) */ Word16 Az[] /* o : interpolated LP parameters in all subfr. (AZ_SIZE) */ ); /* ************************************************************************** * * Function : Int_lpc_1and3_2 * Purpose : Interpolation of the LPC parameters. Same as the Int_lpc * function but we do not recompute Az() for subframe 2 and * 4 because it is already available. * Returns : void * ************************************************************************** */ void Int_lpc_1and3_2 ( Word16 lsp_old[], /* i : LSP vector at the 4th subfr. of past frame (M) */ Word16 lsp_mid[], /* i : LSP vector at the 2nd subframe of present frame (M) */ Word16 lsp_new[], /* i : LSP vector at the 4th subframe of present frame (M) */ Word16 Az[] /* o :interpolated LP parameters in subframes 1 and 3 (AZ_SIZE) */ ); /* ************************************************************************** * * Function : Int_lpc_1to3 * Purpose : Interpolates the LSPs and converts to LPC parameters * to get a different LP filter in each subframe. * Description : The 20 ms speech frame is divided into 4 subframes. * The LSPs are quantized and transmitted at the 4th * subframes (once per frame) and interpolated at the * 1st, 2nd and 3rd subframe. * * |------|------|------|------| * sf1 sf2 sf3 sf4 * F0 F1 * * sf1: 3/4 F0 + 1/4 F1 sf3: 1/4 F0 + 3/4 F1 * sf2: 1/2 F0 + 1/2 F1 sf4: F1 * Returns : void * ************************************************************************** */ void Int_lpc_1to3 ( Word16 lsp_old[], /* i : LSP vector at the 4th SF of past frame (M) */ Word16 lsp_new[], /* i : LSP vector at the 4th SF of present frame (M) */ Word16 Az[] /* o : interpolated LP parameters in all SFs (AZ_SIZE) */ ); /* ************************************************************************** * * Function : Int_lpc_1to3_2 * Purpose : Interpolation of the LPC parameters. Same as the Int_lpc * function but we do not recompute Az() for subframe 4 * because it is already available. * Returns : void * ************************************************************************** */ void Int_lpc_1to3_2 ( Word16 lsp_old[], /* i : LSP vector at the 4th SF of past frame (M) */ Word16 lsp_new[], /* i : LSP vector at the 4th SF present frame (M) */ Word16 Az[] /* o :interpolated LP parameters in SFs 1, 2, 3 (AZ_SIZE) */ ); #endif