FreeCalypso > hg > gsm-codec-lib
view libgsmfrp/internal.h @ 183:452c1d5a6268
libgsmefr BFI w/o data: emit zero output after decoder reset
In real-life usage, each EFR decoder session will most likely begin
with lots of BFI frames before the first real frame arrives. However,
because the spec-defined home state of the decoder is speech rather
than CN, our regular logic for BFI w/o data would have to feed
pseudorandom noise to the decoder (in the "fixed codebook excitation
pulses" part), which is silly to do at the beginning of the decoder
session right out of reset. Therefore, let's check reset_flag_old,
and if we are still in the reset state, simply emit zero output.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Tue, 03 Jan 2023 00:12:18 +0000 |
| parents | 3b64f255689a |
| children | f081a6850fb5 |
line wrap: on
line source
/* * This header file is internal to libgsmfrp; * here we define our state structure. */ enum rx_state { NO_DATA = 0, SPEECH, SPEECH_MUTING, COMFORT_NOISE, LOST_SID, }; struct gsmfr_preproc_state { enum rx_state rx_state; int got_valid_sid; gsm_frame speech_frame; gsm_byte sid_prefix[5]; uint8_t sid_xmaxc[4]; uint32_t cn_random_lfsr; unsigned cn_random_6fold; }; /* we use the same LFSR PRNG for CN as ETSI EFR implementation */ #define PN_INITIAL_SEED 0x70816958L /* Pseudo noise generator seed value */ /* internal functions */ extern void gsmfr_preproc_gen_cn(struct gsmfr_preproc_state *state, gsm_byte *frame); extern uint16_t gsmfr_preproc_prng(struct gsmfr_preproc_state *state, uint16_t no_bits);