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freedv_api.c
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freedv_api.c
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/*---------------------------------------------------------------------------*\
FILE........: freedv_api.c
AUTHOR......: David Rowe
DATE CREATED: August 2014
Library of API functions that implement the FreeDV API, useful for
embedding FreeDV in other programs. Please see:
1. README_freedv.md
2. Notes on function use in this file
3. Simple demo programs in the "demo" directory
4. The full featured command line freedv_tx.c and freedv_rx.c programs
\*---------------------------------------------------------------------------*/
/*
Copyright (C) 2014 David Rowe
All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License version 2.1, as
published by the Free Software Foundation. This program is
distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "freedv_api.h"
#include <assert.h>
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "codec2.h"
#include "codec2_fdmdv.h"
#include "codec2_ofdm.h"
#include "comp_prim.h"
#include "debug_alloc.h"
#include "fdmdv_internal.h"
#include "fmfsk.h"
#include "freedv_api_internal.h"
#include "freedv_vhf_framing.h"
#include "fsk.h"
#include "gp_interleaver.h"
#include "interldpc.h"
#include "mpdecode_core.h"
#include "ofdm_internal.h"
#include "varicode.h"
/* The API version number. The first version is 10. Increment if the API
changes in a way that would require changes by the API user. */
#define VERSION 16
/*
Version 10 Initial version August 2, 2015.
Version 11 September 2015
Added: freedv_zero_total_bit_errors(), freedv_get_sync()
Changed all input and output sample rates to 8000 sps. Rates
for FREEDV_MODE_700 and 700B were 7500.
Version 12 August 2018 Added OFDM configuration switch structure
Version 13 November 2019 Removed 700 and 700B modes
Version 14 May 2020 Number of returned speech samples can vary, use
freedv_get_n_max_speech_samples() to allocate buffers.
Version 15 December 2022 Removing rarely used DPSK support which is not
needed given fast fading modes
Version 16 April 2024, added field to struct freedv_advanced to support
FREEDV_MODE_DATA_CUSTOM
*/
char *ofdm_statemode[] = {"search", "trial", "synced"};
char *rx_sync_flags_to_text[] = {"----", "---T", "--S-", "--ST", "-B--", "-B-T",
"-BS-", "-BST", "E---", "E--T", "E-S-", "E-ST",
"EB--", "EB-T", "EBS-", "EBST"};
/*---------------------------------------------------------------------------* \
FUNCTION....: freedv_open
AUTHOR......: David Rowe
DATE CREATED: 3 August 2014
Call this first to initialise. Returns NULL if initialisation
fails. If a malloc() or calloc() fails in general asserts() will
fire.
\*---------------------------------------------------------------------------*/
struct freedv *freedv_open(int mode) {
// defaults for those modes that support the use of adv
struct freedv_advanced adv = {0, 2, 100, 8000,
1000, 200, "H_256_512_4", NULL};
return freedv_open_advanced(mode, &adv);
}
struct freedv *freedv_open_advanced(int mode, struct freedv_advanced *adv) {
struct freedv *f;
assert(FREEDV_PEAK == OFDM_PEAK);
assert(FREEDV_VARICODE_MAX_BITS == VARICODE_MAX_BITS);
if ((FDV_MODE_ACTIVE(FREEDV_MODE_1600, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700C, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700D, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400A, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400B, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_800XA, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_FSK_LDPC, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC0, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC1, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC3, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC4, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC13, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC14, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATA_CUSTOM, mode)) == false)
return NULL;
/* set everything to zero just in case */
f = (struct freedv *)CALLOC(1, sizeof(struct freedv));
if (f == NULL) return NULL;
f->mode = mode;
if (FDV_MODE_ACTIVE(FREEDV_MODE_1600, mode)) freedv_1600_open(f);
if (FDV_MODE_ACTIVE(FREEDV_MODE_700C, mode)) freedv_700c_open(f);
if (FDV_MODE_ACTIVE(FREEDV_MODE_700D, mode))
freedv_ofdm_voice_open(f, "700D");
if (FDV_MODE_ACTIVE(FREEDV_MODE_700E, mode))
freedv_ofdm_voice_open(f, "700E");
#ifdef __LPCNET__
if (FDV_MODE_ACTIVE(FREEDV_MODE_2020, mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, mode))
freedv_2020x_open(f);
#endif
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400A, mode)) freedv_2400a_open(f);
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400B, mode)) freedv_2400b_open(f);
if (FDV_MODE_ACTIVE(FREEDV_MODE_800XA, mode)) freedv_800xa_open(f);
if (FDV_MODE_ACTIVE(FREEDV_MODE_FSK_LDPC, mode)) freedv_fsk_ldpc_open(f, adv);
if (FDV_MODE_ACTIVE(FREEDV_MODE_DATAC0, mode)) freedv_ofdm_data_open(f, NULL);
if (FDV_MODE_ACTIVE(FREEDV_MODE_DATAC1, mode)) freedv_ofdm_data_open(f, NULL);
if (FDV_MODE_ACTIVE(FREEDV_MODE_DATAC3, mode)) freedv_ofdm_data_open(f, NULL);
if (FDV_MODE_ACTIVE(FREEDV_MODE_DATAC4, mode)) freedv_ofdm_data_open(f, NULL);
if (FDV_MODE_ACTIVE(FREEDV_MODE_DATAC13, mode))
freedv_ofdm_data_open(f, NULL);
if (FDV_MODE_ACTIVE(FREEDV_MODE_DATAC14, mode))
freedv_ofdm_data_open(f, NULL);
if (FDV_MODE_ACTIVE(FREEDV_MODE_DATA_CUSTOM, mode))
freedv_ofdm_data_open(f, adv);
varicode_decode_init(&f->varicode_dec_states, 1);
return f;
}
/*---------------------------------------------------------------------------*\
FUNCTION....: freedv_close
AUTHOR......: David Rowe
DATE CREATED: 3 August 2014
Call to shut down a freedv instance and free memory.
\*---------------------------------------------------------------------------*/
void freedv_close(struct freedv *freedv) {
assert(freedv != NULL);
FREE(freedv->tx_payload_bits);
FREE(freedv->rx_payload_bits);
if (freedv->codec2) codec2_destroy(freedv->codec2);
if (FDV_MODE_ACTIVE(FREEDV_MODE_1600, freedv->mode)) {
FREE(freedv->fdmdv_bits);
FREE(freedv->fdmdv_tx_bits);
FREE(freedv->fdmdv_rx_bits);
fdmdv_destroy(freedv->fdmdv);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_700C, freedv->mode)) {
cohpsk_destroy(freedv->cohpsk);
quisk_filt_destroy(freedv->ptFilter8000to7500);
FREE(freedv->ptFilter8000to7500);
quisk_filt_destroy(freedv->ptFilter7500to8000);
FREE(freedv->ptFilter7500to8000);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_700D, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, freedv->mode)) {
FREE(freedv->rx_syms);
FREE(freedv->rx_amps);
FREE(freedv->ldpc);
ofdm_destroy(freedv->ofdm);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_2020, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, freedv->mode)) {
FREE(freedv->codeword_symbols);
FREE(freedv->codeword_amps);
FREE(freedv->ldpc);
FREE(freedv->passthrough_2020);
ofdm_destroy(freedv->ofdm);
#ifdef __LPCNET__
lpcnet_freedv_destroy(freedv->lpcnet);
#endif
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400A, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_800XA, freedv->mode)) {
fsk_destroy(freedv->fsk);
fvhff_destroy_deframer(freedv->deframer);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400B, freedv->mode)) {
fmfsk_destroy(freedv->fmfsk);
fvhff_destroy_deframer(freedv->deframer);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_FSK_LDPC, freedv->mode)) {
fsk_destroy(freedv->fsk);
FREE(freedv->ldpc);
FREE(freedv->frame_llr);
FREE(freedv->twoframes_llr);
FREE(freedv->twoframes_hard);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_DATAC0, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC1, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC3, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC4, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC13, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC14, freedv->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATA_CUSTOM, freedv->mode)) {
FREE(freedv->rx_syms);
FREE(freedv->rx_amps);
FREE(freedv->ldpc);
ofdm_destroy(freedv->ofdm);
}
FREE(freedv);
}
/* helper function, unpacked bits are much easier to work with inside the modem
*/
static void codec2_encode_upacked(struct freedv *f, uint8_t unpacked_bits[],
short speech_in[]) {
int n_packed = (f->bits_per_codec_frame + 7) / 8;
uint8_t packed_codec_bits[n_packed];
codec2_encode(f->codec2, packed_codec_bits, speech_in);
freedv_unpack(unpacked_bits, packed_codec_bits, f->bits_per_codec_frame);
}
static int is_ofdm_mode(struct freedv *f) {
return FDV_MODE_ACTIVE(FREEDV_MODE_2020, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700D, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC0, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC1, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC3, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC4, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC13, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC14, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATA_CUSTOM, f->mode);
}
static int is_ofdm_data_mode(struct freedv *f) {
return FDV_MODE_ACTIVE(FREEDV_MODE_DATAC0, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC1, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC3, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC4, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC13, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC14, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATA_CUSTOM, f->mode);
}
/*---------------------------------------------------------------------------*\
FUNCTION....: freedv_tx
AUTHOR......: David Rowe
DATE CREATED: 3 August 2014
Takes a frame of input speech samples, encodes and modulates them to
produce a frame of modem samples that can be sent to the
transmitter. See demo/freedv_700d_tx.c for an example.
speech_in[] is sampled at freedv_get_speech_sample_rate() Hz, and
the user must supply exactly freedv_get_n_speech_samples(). The peak
level should be between +/- 16384 and +/- 32767.
The modem signal mod_out[] is sampled at
freedv_get_modem_sample_rate() and is always exactly
freedv_get_n_nom_modem_samples() long. mod_out[] will be scaled
such that the peak level is around +/-16384.
mod_out[] has a higher RMS power than SSB with the same peak level.
In other words, the crest factor or peak to average power ratio is
lower than typical SSB voice. Ensure your transmitter is capable of
continuous high RMS power operation, or consider reducing Tx power.
\*---------------------------------------------------------------------------*/
/* real-valued short output */
void freedv_tx(struct freedv *f, short mod_out[], short speech_in[]) {
assert(f != NULL);
COMP tx_fdm[f->n_nom_modem_samples];
int i;
/* FSK and MEFSK/FMFSK modems work only on real samples. It's simpler to just
* stick them in the real sample tx/rx functions than to add a comp->real
* converter to comptx */
if ((FDV_MODE_ACTIVE(FREEDV_MODE_2400A, f->mode)) ||
(FDV_MODE_ACTIVE(FREEDV_MODE_2400B, f->mode)) ||
(FDV_MODE_ACTIVE(FREEDV_MODE_800XA, f->mode))) {
/* 800XA has two codec frames per modem frame */
if (FDV_MODE_ACTIVE(FREEDV_MODE_800XA, f->mode)) {
codec2_encode(f->codec2, &f->tx_payload_bits[0], &speech_in[0]);
codec2_encode(f->codec2, &f->tx_payload_bits[4], &speech_in[320]);
} else {
codec2_encode(f->codec2, f->tx_payload_bits, speech_in);
}
freedv_tx_fsk_voice(f, mod_out);
} else {
freedv_comptx(f, tx_fdm, speech_in);
for (i = 0; i < f->n_nom_modem_samples; i++) mod_out[i] = tx_fdm[i].real;
}
}
/* complex float output version of freedv_tx() */
void freedv_comptx(struct freedv *f, COMP mod_out[], short speech_in[]) {
assert(f != NULL);
assert(FDV_MODE_ACTIVE(FREEDV_MODE_1600, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700C, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400A, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400B, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700D, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, f->mode));
if (FDV_MODE_ACTIVE(FREEDV_MODE_1600, f->mode)) {
codec2_encode_upacked(f, f->tx_payload_bits, speech_in);
freedv_comptx_fdmdv_1600(f, mod_out);
}
/* all these modes need to pack a bunch of codec frames into one modem frame
* ... */
if (FDV_MODE_ACTIVE(FREEDV_MODE_700C, f->mode)) {
for (int j = 0; j < f->n_codec_frames; j++) {
codec2_encode_upacked(f, f->tx_payload_bits + j * f->bits_per_codec_frame,
speech_in);
speech_in += codec2_samples_per_frame(f->codec2);
}
freedv_comptx_700c(f, mod_out);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_700D, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, f->mode)) {
/* buffer up bits until we get enough encoded bits for interleaver */
for (int j = 0; j < f->n_codec_frames; j++) {
int offset = j * f->bits_per_codec_frame;
codec2_encode_upacked(f, f->tx_payload_bits + offset, speech_in);
speech_in += codec2_samples_per_frame(f->codec2);
}
freedv_comptx_ofdm(f, mod_out);
}
#ifdef __LPCNET__
if (FDV_MODE_ACTIVE(FREEDV_MODE_2020, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, f->mode)) {
/* buffer up bits until we get enough encoded bits for interleaver */
for (int j = 0; j < f->n_codec_frames; j++) {
int offset = j * f->bits_per_codec_frame;
lpcnet_enc(f->lpcnet, speech_in, (char *)f->tx_payload_bits + offset);
speech_in += lpcnet_samples_per_frame(f->lpcnet);
}
freedv_comptx_2020(f, mod_out);
}
#endif
/* 2400 A and B are handled by the real-mode TX */
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400A, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400B, f->mode)) {
codec2_encode(f->codec2, f->tx_payload_bits, speech_in);
freedv_comptx_fsk_voice(f, mod_out);
}
}
/* pack bits */
void freedv_pack(uint8_t *bytes, uint8_t *bits, int nbits) {
memset(bytes, 0, (nbits + 7) / 8);
int bit = 7, byte = 0;
for (int i = 0; i < nbits; i++) {
bytes[byte] |= bits[i] << bit;
bit--;
if (bit < 0) {
bit = 7;
byte++;
}
}
}
/* unpack bits, MSB first */
void freedv_unpack(uint8_t *bits, uint8_t *bytes, int nbits) {
int bit = 7, byte = 0;
for (int i = 0; i < nbits; i++) {
bits[i] = (bytes[byte] >> bit) & 0x1;
bit--;
if (bit < 0) {
bit = 7;
byte++;
}
}
}
/* compute the CRC16 of a frame of unpacked bits */
unsigned short freedv_crc16_unpacked(unsigned char unpacked_bits[], int nbits) {
assert((nbits % 8) == 0);
int nbytes = nbits / 8;
uint8_t packed_bytes[nbytes];
freedv_pack(packed_bytes, unpacked_bits, nbits);
return freedv_gen_crc16(packed_bytes, nbytes);
}
/* Return non-zero if CRC16 of a frame of unpacked bits is correct */
int freedv_check_crc16_unpacked(unsigned char unpacked_bits[], int nbits) {
assert((nbits % 8) == 0);
int nbytes = nbits / 8;
uint8_t packed_bytes[nbytes];
freedv_pack(packed_bytes, unpacked_bits, nbits);
uint16_t tx_crc16 =
(packed_bytes[nbytes - 2] << 8) | packed_bytes[nbytes - 1];
uint16_t rx_crc16 = freedv_crc16_unpacked(unpacked_bits, nbits - 16);
return tx_crc16 == rx_crc16;
}
/* send raw frames of bytes, or speech data that was compressed externally,
* complex float output */
void freedv_rawdatacomptx(struct freedv *f, COMP mod_out[],
unsigned char *packed_payload_bits) {
assert(f != NULL);
freedv_unpack(f->tx_payload_bits, packed_payload_bits,
f->bits_per_modem_frame);
if (FDV_MODE_ACTIVE(FREEDV_MODE_1600, f->mode))
freedv_comptx_fdmdv_1600(f, mod_out);
if (FDV_MODE_ACTIVE(FREEDV_MODE_700C, f->mode))
freedv_comptx_700c(f, mod_out);
if (FDV_MODE_ACTIVE(FREEDV_MODE_700D, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC0, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC1, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC3, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC4, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC13, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATAC14, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_DATA_CUSTOM, f->mode))
freedv_comptx_ofdm(f, mod_out);
if (FDV_MODE_ACTIVE(FREEDV_MODE_FSK_LDPC, f->mode)) {
freedv_tx_fsk_ldpc_data(f, mod_out);
}
}
/* send raw frames of bytes, or speech data that was compressed externally, real
* short output */
void freedv_rawdatatx(struct freedv *f, short mod_out[],
unsigned char *packed_payload_bits) {
assert(f != NULL);
COMP mod_out_comp[f->n_nat_modem_samples];
/* Some FSK modes used packed bits, and coincidentally support real samples
* natively */
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400A, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400B, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_800XA, f->mode)) {
freedv_codec_frames_from_rawdata(f, f->tx_payload_bits,
packed_payload_bits);
freedv_tx_fsk_voice(f, mod_out);
return; /* output is already real */
}
freedv_rawdatacomptx(f, mod_out_comp, packed_payload_bits);
/* convert complex to real */
for (int i = 0; i < f->n_nat_modem_samples; i++)
mod_out[i] = mod_out_comp[i].real;
}
int freedv_rawdatapreamblecomptx(struct freedv *f, COMP mod_out[]) {
assert(f != NULL);
int npreamble_samples = 0;
if (f->mode == FREEDV_MODE_FSK_LDPC) {
struct FSK *fsk = f->fsk;
int npreamble_symbols = 50 * (fsk->mode >> 1);
int npreamble_bits = npreamble_symbols * (fsk->mode >> 1);
npreamble_samples = fsk->Ts * npreamble_symbols;
// fprintf(stderr, "npreamble_symbols: %d npreamble_bits: %d
// npreamble_samples: %d Nbits: %d N: %d\n", npreamble_symbols,
// npreamble_bits, npreamble_samples, fsk->Nbits, fsk->N);
assert(npreamble_samples <
f->n_nom_modem_samples); /* caller probably using an array of this
size */
freedv_tx_fsk_ldpc_data_preamble(f, mod_out, npreamble_bits,
npreamble_samples);
} else if (is_ofdm_data_mode(f)) {
struct OFDM *ofdm = f->ofdm;
complex float *tx_preamble = (complex float *)mod_out;
memcpy(tx_preamble, ofdm->tx_preamble,
sizeof(COMP) * ofdm->samplesperframe);
ofdm_hilbert_clipper(ofdm, tx_preamble, ofdm->samplesperframe);
npreamble_samples = ofdm->samplesperframe;
}
return npreamble_samples;
}
int freedv_rawdatapreambletx(struct freedv *f, short mod_out[]) {
assert(f != NULL);
COMP mod_out_comp[f->n_nat_modem_samples];
int npreamble_samples = freedv_rawdatapreamblecomptx(f, mod_out_comp);
assert(npreamble_samples <= f->n_nat_modem_samples);
/* convert complex to real */
for (int i = 0; i < npreamble_samples; i++) mod_out[i] = mod_out_comp[i].real;
return npreamble_samples;
}
int freedv_rawdatapostamblecomptx(struct freedv *f, COMP mod_out[]) {
assert(f != NULL);
int npostamble_samples = 0;
if (is_ofdm_data_mode(f)) {
struct OFDM *ofdm = f->ofdm;
complex float *tx_postamble = (complex float *)mod_out;
memcpy(tx_postamble, ofdm->tx_postamble,
sizeof(COMP) * ofdm->samplesperframe);
ofdm_hilbert_clipper(ofdm, tx_postamble, ofdm->samplesperframe);
npostamble_samples = ofdm->samplesperframe;
}
return npostamble_samples;
}
int freedv_rawdatapostambletx(struct freedv *f, short mod_out[]) {
assert(f != NULL);
COMP mod_out_comp[f->n_nat_modem_samples];
int npostamble_samples = freedv_rawdatapostamblecomptx(f, mod_out_comp);
assert(npostamble_samples <= f->n_nat_modem_samples);
/* convert complex to real */
for (int i = 0; i < npostamble_samples; i++)
mod_out[i] = mod_out_comp[i].real;
return npostamble_samples;
}
/* VHF packet data tx function */
void freedv_datatx(struct freedv *f, short mod_out[]) {
assert(f != NULL);
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400A, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400B, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_800XA, f->mode)) {
freedv_tx_fsk_data(f, mod_out);
}
}
/* VHF packet data: returns how many tx frames are queued up but not sent yet */
int freedv_data_ntxframes(struct freedv *f) {
assert(f != NULL);
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400A, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400B, f->mode)) {
if (f->deframer->fdc)
return freedv_data_get_n_tx_frames(f->deframer->fdc, 8);
} else if (FDV_MODE_ACTIVE(FREEDV_MODE_800XA, f->mode)) {
if (f->deframer->fdc)
return freedv_data_get_n_tx_frames(f->deframer->fdc, 6);
}
return 0;
}
int freedv_nin(struct freedv *f) {
if (FDV_MODE_ACTIVE(FREEDV_MODE_700C, f->mode))
// For mode 700C, the input rate is 8000 sps, but the modem rate is 7500 sps
// For mode 700C, we request a larger number of Rx samples that will be
// decimated to f->nin samples
return (16 * f->nin + f->ptFilter8000to7500->decim_index) / 15;
else
return f->nin;
}
int freedv_codec_frames_from_rawdata(struct freedv *f,
unsigned char *codec_frames,
unsigned char *rawdata) {
int cbit = 7;
int cbyte = 0;
int rbit = 7;
int rbyte = 0;
int modem_bits = freedv_get_bits_per_modem_frame(f);
int codec_bits = freedv_get_bits_per_codec_frame(f);
int nr_cbits = 0;
int i;
codec_frames[0] = 0;
for (i = 0; i < modem_bits; i++) {
codec_frames[cbyte] |= ((rawdata[rbyte] >> rbit) & 1) << cbit;
rbit--;
if (rbit < 0) {
rbit = 7;
rbyte++;
}
cbit--;
if (cbit < 0) {
cbit = 7;
cbyte++;
codec_frames[cbyte] = 0;
}
nr_cbits++;
if (nr_cbits == codec_bits) {
if (cbit) {
cbyte++;
codec_frames[cbyte] = 0;
}
cbit = 7;
nr_cbits = 0;
}
}
return f->n_codec_frames;
}
int freedv_rawdata_from_codec_frames(struct freedv *f, unsigned char *rawdata,
unsigned char *codec_frames) {
int cbit = 7;
int cbyte = 0;
int rbit = 7;
int rbyte = 0;
int modem_bits = freedv_get_bits_per_modem_frame(f);
int codec_bits = freedv_get_bits_per_codec_frame(f);
int nr_cbits = 0;
int i;
rawdata[rbyte] = 0;
for (i = 0; i < modem_bits; i++) {
rawdata[rbyte] |= ((codec_frames[cbyte] >> cbit) & 1) << rbit;
rbit--;
if (rbit < 0) {
rbit = 7;
rbyte++;
rawdata[rbyte] = 0;
}
cbit--;
if (cbit < 0) {
cbit = 7;
cbyte++;
}
nr_cbits++;
if (nr_cbits == codec_bits) {
if (cbit) cbyte++;
cbit = 7;
nr_cbits = 0;
}
}
return f->n_codec_frames;
}
/*---------------------------------------------------------------------------*\
FUNCTION....: freedv_rx
AUTHOR......: David Rowe
DATE CREATED: 3 August 2014
Takes samples from the radio receiver and decodes
them, producing a frame of decoded speech samples. See
demo/freedv_700d_rx.c for an example.
demod_in[] is an array of received samples sampled at
freedv_get_modem_sample_rate(). To account for difference in the
transmit and receive sample clock frequencies, the number of
demod_in[] samples is time varying. You MUST call freedv_nin()
BEFORE EACH call to freedv_rx() and pass exactly that many samples
to this function:
short demod_in[freedv_get_n_max_modem_samples(f)];
short speech_out[freedv_get_n_max_speech_samples(f)];
nin = freedv_nin(f); // num input samples for first read
while(fread(demod_in, sizeof(short), nin, fin) == nin) {
nout = freedv_rx(f, speech_out, demod_in);
fwrite(speech_out, sizeof(short), nout, fout);
nin = freedv_nin(f); // num input samples for next read
}
To help set your buffer sizes, The maximum value of freedv_nin() is
freedv_get_n_max_modem_samples().
freedv_rx() returns the number of output speech samples available in
speech_out[], which is sampled at freedv_get_speech_sample_rate().
You should ALWAYS check the return value of freedv_rx(), and read
EXACTLY that number of speech samples from speech_out[].
Not every call to freedv_rx will return speech samples; in some
modes several modem frames are processed before speech samples are
returned. When squelch is active, zero samples may be returned.
The peak level of demod_in[] is not critical, as the demod works
well over a wide range of amplitude scaling. However avoid clipping
(overload, or samples pinned to +/- 32767). speech_out[] will peak
at just less than +/-32767.
When squelch is disabled, this function echoes the demod_in[]
samples to speech_out[]. This allows the user to listen to the
channel, which is useful for tuning FreeDV signals or reception of
non-FreeDV signals.
\*---------------------------------------------------------------------------*/
int freedv_rx(struct freedv *f, short speech_out[], short demod_in[]) {
assert(f != NULL);
int i;
int nin = freedv_nin(f);
f->nin_prev = nin;
assert(nin <= f->n_max_modem_samples);
/* FSK Rx happens in real floats, so convert to those and call their demod
* here */
if (FDV_MODE_ACTIVE(FREEDV_MODE_2400A, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2400B, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_800XA, f->mode)) {
float rx_float[f->n_max_modem_samples];
for (i = 0; i < nin; i++) {
rx_float[i] = ((float)demod_in[i]);
}
return freedv_floatrx(f, speech_out, rx_float);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_1600, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700C, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, f->mode)) {
float gain = 1.0f;
assert(nin <= f->n_max_modem_samples);
COMP rx_fdm[f->n_max_modem_samples];
for (i = 0; i < nin; i++) {
rx_fdm[i].real = gain * (float)demod_in[i];
rx_fdm[i].imag = 0.0f;
}
return freedv_comprx(f, speech_out, rx_fdm);
}
/* special low memory version for 700D, to help with stm32 port */
if (FDV_MODE_ACTIVE(FREEDV_MODE_700D, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, f->mode)) {
float gain = 2.0f; /* keep levels the same as Octave simulations and C unit
tests for real signals */
return freedv_shortrx(f, speech_out, demod_in, gain);
}
assert(1); /* should never get here */
return 0;
}
/* complex sample input version of freedv_rx() */
int freedv_comprx(struct freedv *f, short speech_out[], COMP demod_in[]) {
assert(f != NULL);
assert(f->nin <= f->n_max_modem_samples);
int rx_status = 0;
f->nin_prev = freedv_nin(f);
if (FDV_MODE_ACTIVE(FREEDV_MODE_1600, f->mode)) {
rx_status = freedv_comprx_fdmdv_1600(f, demod_in);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_700C, f->mode)) {
rx_status = freedv_comprx_700c(f, demod_in);
}
if ((FDV_MODE_ACTIVE(FREEDV_MODE_2400A, f->mode)) ||
(FDV_MODE_ACTIVE(FREEDV_MODE_2400B, f->mode)) ||
(FDV_MODE_ACTIVE(FREEDV_MODE_800XA, f->mode))) {
rx_status = freedv_comprx_fsk(f, demod_in);
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_700D, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, f->mode)) {
rx_status =
freedv_comp_short_rx_ofdm(f, (void *)demod_in, 0, 2.0f); // was 1.0 ??
}
if (FDV_MODE_ACTIVE(FREEDV_MODE_2020, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, f->mode)) {
#ifdef __LPCNET__
rx_status = freedv_comprx_2020(f, demod_in);
#endif
}
short demod_in_short[f->nin_prev];
for (int i = 0; i < f->nin_prev; i++) demod_in_short[i] = demod_in[i].real;
return freedv_bits_to_speech(f, speech_out, demod_in_short, rx_status);
}
/* memory efficient real short version - just for 700D on the SM1000 */
int freedv_shortrx(struct freedv *f, short speech_out[], short demod_in[],
float gain) {
assert(f != NULL);
int rx_status = 0;
f->nin_prev = f->nin;
// At this stage short interface only supported for 700D, to help
// memory requirements on stm32
assert((f->mode == FREEDV_MODE_700D) || (f->mode == FREEDV_MODE_700E));
assert(f->nin <= f->n_max_modem_samples);
if (FDV_MODE_ACTIVE(FREEDV_MODE_700D, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, f->mode)) {
rx_status = freedv_comp_short_rx_ofdm(f, (void *)demod_in, 1, gain);
}
return freedv_bits_to_speech(f, speech_out, demod_in, rx_status);
}
/* helper function, unpacked bits are much easier to work with inside the modem
*/
static void codec2_decode_upacked(struct freedv *f, short speech_out[],
uint8_t unpacked_bits[]) {
int n_packed = (f->bits_per_codec_frame + 7) / 8;
uint8_t packed_codec_bits[n_packed];
freedv_pack(packed_codec_bits, unpacked_bits, f->bits_per_codec_frame);
codec2_decode(f->codec2, speech_out, packed_codec_bits);
}
/*---------------------------------------------------------------------------* \
FUNCTION....: freedv_rx_bits_to_speech
AUTHOR......: David Rowe
DATE CREATED: May 2020
The *_rx functions takes off air samples, demodulates and (for some
modes) FEC decodes, giving us a frame of bits.
This function captures a lot of tricky logic that has been distilled
through experience:
There may not be a frame of bits returned on every call freedv_*rx* call.
When there are valid bits we need to run the speech decoder.
We may not have demod sync, so various pass through options may happen
with the input samples.
We may squelch based on SNR.
Need to handle various codecs, and varying number of codec frames per modem
frame.
Squelch audio if test frames are being sent.
Determine how many speech samples to return, which will vary if in
sync/out of sync Work with real and complex inputs (complex wrapper)
Attenuate audio on pass through.
Deal with 700D first frame burble, and different sync states from OFDM
modes like 700D.
Output no samples if squelched, we assume it's OK for the audio sink to run
dry.
A FIFO is required on output to smooth sample flow to audio sink.
Don't decode when we are sending test frames
\*---------------------------------------------------------------------------*/
int freedv_bits_to_speech(struct freedv *f, short speech_out[],
short demod_in[], int rx_status) {
int nout = 0;
int decode_speech = 0;
if ((rx_status & FREEDV_RX_SYNC) == 0) {
if (!f->squelch_en) {
/* pass through received samples so we can hear what's going on, e.g.
* during tuning */
if ((f->mode == FREEDV_MODE_2020) || (f->mode == FREEDV_MODE_2020B)) {
/* 8kHz modem sample rate but 16 kHz speech sample
rate, so we need to resample */
nout = 2 * f->nin_prev;
assert(nout <= freedv_get_n_max_speech_samples(f));
float tmp[nout];
for (int i = 0; i < nout / 2; i++)
f->passthrough_2020[FDMDV_OS_TAPS_16K + i] = demod_in[i];
fdmdv_8_to_16(tmp, &f->passthrough_2020[FDMDV_OS_TAPS_16K], nout / 2);
for (int i = 0; i < nout; i++)
speech_out[i] = f->passthrough_gain * tmp[i];
} else {
/* Speech and modem rates might be different */
int rate_factor = f->modem_sample_rate / f->speech_sample_rate;
nout = f->nin_prev / rate_factor;
for (int i = 0; i < nout; i++)
speech_out[i] = f->passthrough_gain * demod_in[i * rate_factor];
}
}
}
if ((rx_status & FREEDV_RX_SYNC) && (rx_status & FREEDV_RX_BITS) &&
!f->test_frames) {
/* following logic is tricky so spell it out clearly, see table
in: https://github.com/drowe67/codec2/pull/111 */
if (!f->squelch_en) {
decode_speech = 1;
} else {
/* squelch is enabled */
/* anti-burble case - don't decode on trial sync unless the
frame has no bit errors. This prevents short lived trial
sync cases generating random bursts of audio */
if (rx_status & FREEDV_RX_TRIAL_SYNC) {
if ((rx_status & FREEDV_RX_BIT_ERRORS) == 0) decode_speech = 1;
} else {
/* sync is solid - decode even through fades as there is still some
* speech info there */
if (f->snr_est > f->snr_squelch_thresh) decode_speech = 1;
}
}
}
if (decode_speech) {
if (FDV_MODE_ACTIVE(FREEDV_MODE_2020, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_2020B, f->mode)) {
#ifdef __LPCNET__
/* LPCNet decoder */
int bits_per_codec_frame = lpcnet_bits_per_frame(f->lpcnet);
int data_bits_per_frame = f->ldpc->data_bits_per_frame;
int frames = data_bits_per_frame / bits_per_codec_frame;
nout = f->n_speech_samples;
for (int i = 0; i < frames; i++) {
lpcnet_dec(f->lpcnet,
(char *)f->rx_payload_bits + i * bits_per_codec_frame,
speech_out);
/* ear protection: on frames with errors and clipping, reduce level by
* 12dB */
if (rx_status & FREEDV_RX_BIT_ERRORS) {
int max = 0.0;
for (int j = 0; j < lpcnet_samples_per_frame(f->lpcnet); j++)
if (abs(speech_out[j]) > max) max = abs(speech_out[j]);
if (max == 32767)
for (int j = 0; j < lpcnet_samples_per_frame(f->lpcnet); j++)
speech_out[j] *= 0.25;
}
speech_out += lpcnet_samples_per_frame(f->lpcnet);
}
#endif
} else {
/* codec 2 decoder */
if (FDV_MODE_ACTIVE(FREEDV_MODE_700D, f->mode) ||
FDV_MODE_ACTIVE(FREEDV_MODE_700E, f->mode)) {
nout = f->n_speech_samples;
for (int i = 0; i < f->n_codec_frames; i++) {