FreeCalypso > hg > gsm-codec-lib
view amrtest/tseq-dec.c @ 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 | edbbbf1c4ab1 |
children |
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/* * twamr-tseq-dec is a test program for our AMR decoder: it reads * 3GPP AMR *.cod files as input and writes 16-bit linear PCM (raw) * files as output, allowing libtwamr decoder to be tested with the * official test sequences. * * Both input and output are read/written in the host machine's * native byte order. */ #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <string.h> #include <strings.h> #include <unistd.h> #include "../libtwamr/tw_amr.h" static int read_input(inf, cod, filename_for_errs) FILE *inf; uint16_t *cod; char *filename_for_errs; { int cc; cc = fread(cod, 2, AMR_COD_WORDS, inf); if (cc == 0) return 0; if (cc != AMR_COD_WORDS) { fprintf(stderr, "error: short read from %s\n", filename_for_errs); exit(1); } return 1; } main(argc, argv) char **argv; { char *infname, *outfname; FILE *inf, *outf; struct amr_decoder_state *state; uint16_t cod[AMR_COD_WORDS]; struct amr_param_frame frame; int16_t pcm[160]; int opt, use_rxtype = 0, rc; unsigned frame_no; extern int optind; while ((opt = getopt(argc, argv, "r")) != EOF) { switch (opt) { case 'r': use_rxtype = 1; continue; default: usage: fprintf(stderr, "usage: %s [-r] input.cod output.out\n", argv[0]); exit(1); } } if (argc != optind + 2) goto usage; infname = argv[optind]; outfname = argv[optind+1]; inf = fopen(infname, "r"); if (!inf) { perror(infname); exit(1); } outf = fopen(outfname, "w"); if (!outf) { perror(outfname); exit(1); } state = amr_decoder_create(); if (!state) { perror("amr_decoder_create()"); exit(1); } for (frame_no = 0; ; frame_no++) { rc = read_input(inf, cod, infname); if (!rc) break; rc = amr_frame_from_tseq(cod, use_rxtype, &frame); if (rc < 0) { fprintf(stderr, "error in %s frame %u: amr_frame_from_tseq() returned %d\n", infname, frame_no, rc); exit(1); } amr_decode_frame(state, &frame, pcm); fwrite(pcm, 2, 160, outf); } fclose(outf); exit(0); }