FreeCalypso > hg > gsm-codec-lib
view libgsmefr/dec_state.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 | eefef9f6d533 |
| children |
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/* * In this header file we define our decoder state structure. * This decoder state structure is internal to libgsmefr, * NOT part of our external public interface! */ struct EFR_decoder_state { /* from agc.c */ Word16 past_gain; /* from decoder.c */ Word16 synth_buf[L_FRAME + M]; Word16 reset_flag_old; /* from dec_12k2.c */ Word16 old_exc[L_FRAME + PIT_MAX + L_INTERPOL]; Word16 lsp_old[M]; Word16 mem_syn[M]; Word16 prev_bf; Word16 bf_state; /* from d_plsf_5.c */ Word16 past_r2_q[M]; Word16 past_lsf_q[M]; Word16 lsf_p_CN[M]; Word16 lsf_old_CN[M]; Word16 lsf_new_CN[M]; /* from d_gains.c */ Word16 pbuf[5]; Word16 past_gain_pit; Word16 prev_gp; Word16 gbuf[5]; Word16 past_gain_code; Word16 prev_gc; Word16 gcode0_CN; Word16 gain_code_old_CN; Word16 gain_code_new_CN; Word16 gain_code_muting_CN; Word16 past_qua_en[4]; Word16 pred[4]; /* from dtx.c */ Word16 rxdtx_ctrl; Word32 L_pn_seed_rx; Word16 rx_dtx_state; Word16 rxdtx_aver_period; Word16 rxdtx_N_elapsed; Word16 prev_SID_frames_lost; Word16 buf_p_rx; Word16 lsf_old_rx[DTX_HANGOVER][M]; Word16 gain_code_old_rx[4 * DTX_HANGOVER]; /* from dec_lag6.c */ Word16 old_T0; /* from preemph.c */ Word16 mem_pre; /* from pstfilt2.c */ Word16 res2[L_SUBFR]; Word16 mem_syn_pst[M]; /* our own addition */ Word32 L_pn_seed_nodata; };