FreeCalypso > hg > gsm-codec-lib
view libtwamr/int_lpc.h @ 477:4c9222d95647
libtwamr encoder: always emit frame->mode = mode;
In the original implementation of amr_encode_frame(), the 'mode' member
of the output struct was set to 0xFF if the output frame type is TX_NO_DATA.
This design was made to mimic the mode field (16-bit word) being set to
0xFFFF (or -1) in 3GPP test sequence format - but nothing actually depends
on this struct member being set in any way, and amr_frame_to_tseq()
generates the needed 0xFFFF on its own, based on frame->type being equal
to TX_NO_DATA.
It is simpler and more efficient to always set frame->mode to the actual
encoding mode in amr_encode_frame(), and this new behavior has already
been documented in doc/AMR-library-API description in anticipation of
the present change.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Sat, 18 May 2024 22:30:42 +0000 |
| parents | 32bc48faec4b |
| children |
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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