FreeCalypso > hg > gsm-codec-lib
view libtwamr/cl_ltp.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 | 85e9768d497f |
| 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 : cl_ltp.h * Purpose : Closed-loop fractional pitch search * ******************************************************************************** */ #ifndef cl_ltp_h #define cl_ltp_h "$Id $" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "tw_amr.h" #include "typedef.h" #include "pitch_fr.h" #include "ton_stab.h" /* ******************************************************************************** * LOCAL VARIABLES AND TABLES ******************************************************************************** */ /* ******************************************************************************** * DEFINITION OF DATA TYPES ******************************************************************************** */ /* state variable */ typedef struct { Pitch_frState pitchSt; } clLtpState; /* ******************************************************************************** * DECLARATION OF PROTOTYPES ******************************************************************************** */ void cl_ltp_reset (clLtpState *st); /* reset of pre processing state (i.e. set state memory to zero) returns 0 on success */ int cl_ltp( clLtpState *clSt, /* i/o : State struct */ tonStabState *tonSt, /* i/o : State struct */ enum Mode mode, /* i : coder mode */ Word16 frameOffset, /* i : Offset to subframe */ Word16 T_op[], /* i : Open loop pitch lags */ Word16 *h1, /* i : Impulse response vector Q12 */ Word16 *exc, /* i/o : Excitation vector Q0 */ Word16 res2[], /* i/o : Long term prediction residual Q0 */ Word16 xn[], /* i : Target vector for pitch search Q0 */ Word16 lsp_flag, /* i : LSP resonance flag */ Word16 xn2[], /* o : Target vector for codebook search Q0 */ Word16 y1[], /* o : Filtered adaptive excitation Q0 */ Word16 *T0, /* o : Pitch delay (integer part) */ Word16 *T0_frac, /* o : Pitch delay (fractional part) */ Word16 *gain_pit, /* o : Pitch gain Q14 */ Word16 g_coeff[], /* o : Correlations between xn, y1, & y2 */ Word16 **anap, /* o : Analysis parameters */ Word16 *gp_limit /* o : pitch gain limit */ ); #endif