FreeCalypso > hg > gsm-codec-lib
view libtwamr/c_g_aver.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 | dc3b7caa59c4 |
| 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 : c_g_aver.h * Purpose : Background noise source charateristic detector (SCD) * ******************************************************************************** */ #ifndef c_g_aver_h #define c_g_aver_h "$Id $" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "tw_amr.h" #include "typedef.h" #include "cnst.h" /* ******************************************************************************** * LOCAL VARIABLES AND TABLES ******************************************************************************** */ #define L_CBGAINHIST 7 /* ******************************************************************************** * DEFINITION OF DATA TYPES ******************************************************************************** */ typedef struct{ /* history vector of past synthesis speech energy */ Word16 cbGainHistory[L_CBGAINHIST]; /* state flags */ Word16 hangVar; /* counter; */ Word16 hangCount; /* counter; */ } Cb_gain_averageState; /* ******************************************************************************** * DECLARATION OF PROTOTYPES ******************************************************************************** */ /* ************************************************************************** * * Function : Cb_gain_average_reset * Purpose : Resets state memory * Returns : 0 on success * ************************************************************************** */ void Cb_gain_average_reset (Cb_gain_averageState *st); /* ************************************************************************** * * Function : Cb_gain_average * Purpose : Charaterice synthesis speech and detect background noise * Returns : background noise decision; 0 = bgn, 1 = no bgn * ************************************************************************** */ Word16 Cb_gain_average ( Cb_gain_averageState *st, /* i/o : State variables for CB gain avergeing */ enum Mode mode, /* i : AMR mode */ Word16 gain_code, /* i : CB gain Q1 */ Word16 lsp[], /* i : The LSP for the current frame Q15 */ Word16 lspAver[], /* i : The average of LSP for 8 frames Q15 */ Word16 bfi, /* i : bad frame indication flag */ Word16 prev_bf, /* i : previous bad frame indication flag */ Word16 pdfi, /* i : potential degraded bad frame ind flag */ Word16 prev_pdf, /* i : prev pot. degraded bad frame ind flag */ Word16 inBackgroundNoise, /* i : background noise decision */ Word16 voicedHangover /* i : # of frames after last voiced frame */ ); #endif