FreeCalypso > hg > gsm-codec-lib
view libtwamr/dtx_enc.h @ 581:e2d5cad04cbf
libgsmhr1 RxFE: store CN R0+LPC separately from speech
In the original GSM 06.06 code the ECU for speech mode is entirely
separate from the CN generator, maintaining separate state. (The
main intertie between them is the speech vs CN state variable,
distinguishing between speech and CN BFIs, in addition to the
CN-specific function of distinguishing between initial and update
SIDs.)
In the present RxFE implementation I initially thought that we could
use the same saved_frame buffer for both ECU and CN, overwriting
just the first 4 params (R0 and LPC) when a valid SID comes in.
However, I now realize it was a bad idea: the original code has a
corner case (long sequence of speech-mode BFIs to put the ECU in
state 6, then SID and CN-mode BFIs, then a good speech frame) that
would be broken by that buffer reuse approach. We could eliminate
this corner case by resetting the ECU state when passing through
a CN insertion period, but doing so would needlessly increase
the behavioral diffs between GSM 06.06 and our version.
Solution: use a separate CN-specific buffer for CN R0+LPC parameters,
and match the behavior of GSM 06.06 code in this regard.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 13 Feb 2025 10:02:45 +0000 |
| parents | 5a1d18542f8a |
| children |
line wrap: on
line source
/* ******************************************************************************** * * 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 : dtx_enc.h * Purpose : DTX mode computation of SID parameters * ******************************************************************************** */ #ifndef dtx_enc_h #define dtx_enc_h "$Id $" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "tw_amr.h" #include "typedef.h" #include "cnst.h" #include "q_plsf.h" #include "gc_pred.h" #include "dtx_common.h" /* ******************************************************************************** * DEFINITION OF DATA TYPES ******************************************************************************** */ typedef struct { Word16 lsp_hist[M * DTX_HIST_SIZE]; Word16 log_en_hist[DTX_HIST_SIZE]; Word16 hist_ptr; Word16 log_en_index; Word16 init_lsf_vq_index; Word16 lsp_index[3]; /* DTX handler stuff */ Word16 dtxHangoverCount; Word16 decAnaElapsedCount; } dtx_encState; /* ******************************************************************************** * DECLARATION OF PROTOTYPES ******************************************************************************** */ /* ************************************************************************** * * Function : dtx_enc_reset * Purpose : Resets state memory * Returns : 0 on success * ************************************************************************** */ void dtx_enc_reset (dtx_encState *st); /* ************************************************************************** * * Function : dtx_enc * Purpose : * Description : * ************************************************************************** */ int dtx_enc(dtx_encState *st, /* i/o : State struct */ Word16 computeSidFlag, /* i : compute SID */ Q_plsfState *qSt, /* i/o : Qunatizer state struct */ gc_predState* predState, /* i/o : State struct */ Word16 **anap /* o : analysis parameters */ ); /* ************************************************************************** * * Function : dtx_buffer * Purpose : handles the DTX buffer * ************************************************************************** */ int dtx_buffer(dtx_encState *st, /* i/o : State struct */ Word16 lsp_new[], /* i : LSP vector */ Word16 speech[] /* i : speech samples */ ); /* ************************************************************************** * * Function : tx_dtx_handler * Purpose : adds extra speech hangover to analyze speech on the decoding side. * Description : returns 1 when a new SID analysis may be made * otherwise it adds the appropriate hangover after a sequence * with out updates of SID parameters . * ************************************************************************** */ Word16 tx_dtx_handler(dtx_encState *st, /* i/o : State struct */ Word16 vadFlag, /* i : vad control variable */ enum Mode *usedMode /* o : mode changed or not */ ); #endif