FreeCalypso > hg > gsm-codec-lib
view libtwamr/dhf_subst2.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 | fa0652115168 |
| children |
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/* * The function implemented in this module is an aid for AMR-EFR interworking; * it is meant to be invoked directly after amr_encode_frame(). It checks * the encoder output for MR122 DHF and turns it into EFR DHF just like * amr_dhf_subst_efr(), but only if the input PCM frame was an EHF. This * slightly more complicated logic is needed in order to replicate the observed * behavior of AMR-EFR speech encoder in the extant GSM network of T-Mobile USA. */ #include "tw_amr.h" #include "namespace.h" #include "e_homing.h" void amr_dhf_subst_efr2(struct amr_param_frame *frame, const int16_t *pcm) { if (encoder_homing_frame_test(pcm)) amr_dhf_subst_efr(frame); }
