FreeCalypso > hg > gsm-codec-lib
view libtwamr/dhf_check.c @ 605:63f774192906
gsmhr_decoder_twts002_in(): set BFI=1 SID=1 for invalid SID
When a received TW-TS-002 RTP payload indicates invalid SID,
which of the 3 possible BFI/SID combinations should we pass to
our internal ETSI-based speech decoder or TFO engine?
Our original code passed BFI=0 SID=1, but upon further reflection,
BFI=1 SID=1 is a better choice. In the corner case where received
invalid SID is fed to a full decoder in homed state, setting BFI=1
allows that decoder to emit zeros on PCM and stay homed, instead of
launching into full decoding.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 04 Dec 2025 21:01:46 +0000 |
| parents | 9beb01439a90 |
| children |
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/* * This module implements the DHF checking function. */ #include <stdint.h> #include <string.h> #include "tw_amr.h" #include "typedef.h" #include "namespace.h" #include "bitno.h" static const Word16 * const dhf_per_mode[8] = { amr_dhf_mr475, amr_dhf_mr515, amr_dhf_mr59, amr_dhf_mr67, amr_dhf_mr74, amr_dhf_mr795, amr_dhf_mr102, amr_dhf_mr122 }; int amr_check_dhf(const struct amr_param_frame *frame, int first_sub_only) { const Word16 *table; Word16 nparam; if (frame->type != RX_SPEECH_GOOD) return 0; if ((frame->mode & 0x87) == 0x87) table = amr_dhf_gsmefr; else table = dhf_per_mode[frame->mode & 7]; if (first_sub_only) nparam = prmnofsf[frame->mode & 7]; else nparam = prmno[frame->mode & 7]; if (memcmp(frame->param, table, nparam * sizeof(int16_t))) return 0; else return 1; }
