FreeCalypso > hg > gsm-codec-lib
view libtwamr/pitch_fr.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 | be8edf9e6bc1 |
| 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 : pitch_fr.h * Purpose : Find the pitch period with 1/3 or 1/6 subsample * : resolution (closed loop). * ******************************************************************************** */ #ifndef pitch_fr_h #define pitch_fr_h "$Id $" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "tw_amr.h" #include "typedef.h" /* ******************************************************************************** * DEFINITION OF DATA TYPES ******************************************************************************** */ typedef struct { Word16 T0_prev_subframe; /* integer pitch lag of previous sub-frame */ } Pitch_frState; /* ******************************************************************************** * DECLARATION OF PROTOTYPES ******************************************************************************** */ void Pitch_fr_reset (Pitch_frState *st); /* reset of pre processing state (i.e. set state memory to zero) returns 0 on success */ Word16 Pitch_fr ( /* o : pitch period (integer) */ Pitch_frState *st, /* i/o : State struct */ enum Mode mode, /* i : codec mode */ Word16 T_op[], /* i : open loop pitch lags */ Word16 exc[], /* i : excitation buffer */ Word16 xn[], /* i : target vector */ Word16 h[], /* i : impulse response of synthesis and weighting filters */ Word16 L_subfr, /* i : Length of subframe */ Word16 i_subfr, /* i : subframe offset */ Word16 *pit_frac, /* o : pitch period (fractional) */ Word16 *resu3, /* o : subsample resolution 1/3 (=1) or 1/6 (=0) */ Word16 *ana_index /* o : index of encoding */ ); #endif