view efrtest/etsi-dec.c @ 242:f081a6850fb5

libgsmfrp: new refined implementation The previous implementation exhibited the following defects, which are now fixed: 1) The last received valid SID was cached forever for the purpose of handling future invalid SIDs - we could have received some valid SID ages ago, then lots of speech or NO_DATA, and if we then get an invalid SID, we would resurrect the last valid SID from ancient history - a bad design. In our new design, we handle invalid SID based on the current state, much like BFI. 2) GSM 06.11 spec says clearly that after the second lost SID (received BFI=1 && TAF=1 in CN state) we need to gradually decrease the output level, rather than jump directly to emitting silence frames - we previously failed to implement such logic. 3) Per GSM 06.12 section 5.2, Xmaxc should be the same in all 4 subframes in a SID frame. What should we do if we receive an otherwise valid SID frame with different Xmaxc? Our previous approach would replicate this Xmaxc oddity in every subsequent generated CN frame, which is rather bad. In our new design, the very first CN frame (which can be seen as a transformation of the SID frame itself) retains the original 4 distinct Xmaxc, but all subsequent CN frames are based on the Xmaxc from the last subframe of the most recent SID.
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 09 May 2023 05:16:31 +0000
parents da17c7f02c6c
children 9f354d2aea13
line wrap: on
line source

/*
 * gsmefr-etsi-dec is a test program for our EFR decoder: it reads ETSI's
 * .dec format as input and writes raw 16-bit PCM (same as ETSI's *.out)
 * as output, allowing our decoder to be tested with ETSI's official test
 * sequences.
 *
 * ETSI input and output files are read and written in LE byte order
 * by default, or in BE byte order if -b option is given.
 */

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include "../libgsmefr/gsm_efr.h"
#include "etsi.h"

static void
write_pcm_be(outf, pcm)
	FILE *outf;
	int16_t *pcm;
{
	uint8_t bytes[320], *dp;
	int16_t samp;
	unsigned n;

	dp = bytes;
	for (n = 0; n < 160; n++) {
		samp = pcm[n];
		*dp++ = (samp >> 8) & 0xFF;
		*dp++ = samp & 0xFF;
	}
	fwrite(bytes, 2, 160, outf);
}

static void
write_pcm_le(outf, pcm)
	FILE *outf;
	int16_t *pcm;
{
	uint8_t bytes[320], *dp;
	int16_t samp;
	unsigned n;

	dp = bytes;
	for (n = 0; n < 160; n++) {
		samp = pcm[n];
		*dp++ = samp & 0xFF;
		*dp++ = (samp >> 8) & 0xFF;
	}
	fwrite(bytes, 2, 160, outf);
}

main(argc, argv)
	char **argv;
{
	int big_endian;
	char *infname, *outfname;
	FILE *inf, *outf;
	struct EFR_decoder_state *state;
	unsigned frame_no;
	uint8_t input_bits[ETSI_DEC_NWORDS], frame[EFR_RTP_FRAME_LEN];
	int16_t pcm[160];
	int rc;

	if (argc == 3 && argv[1][0] != '-') {
		big_endian = 0;
		infname = argv[1];
		outfname = argv[2];
	} else if (argc == 4 && !strcmp(argv[1], "-b")) {
		big_endian = 1;
		infname = argv[2];
		outfname = argv[3];
	} else {
		fprintf(stderr, "usage: %s [-b] input.dec output.out\n",
			argv[0]);
		exit(1);
	}
	inf = fopen(infname, "r");
	if (!inf) {
		perror(infname);
		exit(1);
	}
	outf = fopen(outfname, "w");
	if (!outf) {
		perror(outfname);
		exit(1);
	}
	state = EFR_decoder_create();
	if (!state) {
		perror("EFR_decoder_create()");
		exit(1);
	}
	for (frame_no = 0; ; frame_no++) {
		rc = read_etsi_bits(inf, big_endian, input_bits,
				    ETSI_DEC_NWORDS, infname);
		if (!rc)
			break;
		if (input_bits[0] > 1) {
			fprintf(stderr, "error in %s frame #%u: BFI > 1\n",
				infname, frame_no);
			exit(1);
		}
		bits2frame(input_bits + 1, frame, infname, frame_no);
		if (input_bits[245] > 2) {
			fprintf(stderr, "error in %s frame #%u: SID > 2\n",
				infname, frame_no);
			exit(1);
		}
		if (input_bits[246] > 1) {
			fprintf(stderr, "error in %s frame #%u: TAF > 1\n",
				infname, frame_no);
			exit(1);
		}
		rc = EFR_sid_classify(frame);
		if (input_bits[245] != rc) {
			fprintf(stderr,
"warning: frame #%u has mismatching SID (file says %u, analysis yields %d)\n",
				frame_no, input_bits[245], rc);
		}
		EFR_decode_frame(state, frame, input_bits[0], input_bits[246],
				 pcm);
		if (big_endian)
			write_pcm_be(outf, pcm);
		else
			write_pcm_le(outf, pcm);
	}
	fclose(outf);
	exit(0);
}