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/* Iridium AMBE vocoder - AMBE API */
/* (C) 2015 by Sylvain Munaut <tnt@246tNt.com>
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*! \addtogroup codec
* @{
*/
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "ambe.h"
#include "private.h"
/*! \brief Allocates and inits a decoder object
* \returns A newly allocated and initialized decoder
*/
struct ir77_ambe_decoder *
ir77_ambe_decode_alloc(void)
{
struct ir77_ambe_decoder *dec;
dec = calloc(1, sizeof(struct ir77_ambe_decoder));
if (!dec)
return NULL;
ir77_ambe_synth_init(&dec->synth);
dec->sf_prev.w0 = 0.09378;
dec->sf_prev.f0 = dec->sf_prev.w0 / (2 * M_PIf);
dec->sf_prev.L = 30;
return dec;
}
/*! \brief Release a decoder object created by \ref ir77_ambe_decode_alloc
* \param[in] dec Decoder object
*/
void
ir77_ambe_decode_release(struct ir77_ambe_decoder *dec)
{
free(dec);
}
/*! \brief Decodes an AMBE frame to audio
* \param[in] dec Decoder object
* \param[out] audio Output audio buffers
* \param[in] N number of audio samples to produce (== 360 for now)
* \param[in] frame Frame data (as de-prioritized 103 ubits), Must be speech !
* \returns 0 for success. Negative error code otherwise.
*/
static int
ir77_ambe_decode_speech(struct ir77_ambe_decoder *dec,
int16_t *audio, int N, const ubit_t *frame_lin)
{
struct ir77_ambe_raw_params rp;
struct ir77_ambe_subframe sf[2];
/* Read out params */
ir77_ambe_frame_unpack_raw(&rp, frame_lin);
/* Decode params */
ir77_ambe_frame_decode_params(sf, &dec->sf_prev, &rp);
/* Expand them */
ir77_ambe_subframe_expand(&sf[0]);
ir77_ambe_subframe_expand(&sf[1]);
/* Perform the actual audio synthesis */
ir77_ambe_synth_enhance(&dec->synth, &sf[0]);
ir77_ambe_synth_enhance(&dec->synth, &sf[1]);
ir77_ambe_synth_audio(&dec->synth, audio , &sf[0], &dec->sf_prev);
ir77_ambe_synth_audio(&dec->synth, audio + 180, &sf[1], &sf[0]);
/* Save previous subframe */
memcpy(&dec->sf_prev, &sf[1], sizeof(struct ir77_ambe_subframe));
return 0;
}
/*! \brief Decodes an AMBE superframe to audio
* \param[in] dec Decoder object
* \param[out] audio Output audio buffers
* \param[in] N number of audio samples to produce (== 720 for now)
* \param[in] superframe SuperFrame data (39 bytes = 312 bits)
* \returns 0 for success. Negative error code otherwise.
*/
int
ir77_ambe_decode_superframe(struct ir77_ambe_decoder *dec,
int16_t *audio, int N,
const uint8_t *superframe)
{
ubit_t superframe_bits[312];
ubit_t frame_bits[156];
int i;
/* Unpack to ubits */
osmo_pbit2ubit_ext(superframe_bits, 0, superframe, 0, 312, 1);
/* Process each frame */
for (i=0; i<2; i++)
{
ubit_t frame[103], frame_lin[103];
enum ir77_ambe_frame_type type;
int err[6];
uint32_t seed;
/* De-interleave */
ir77_ambe_interleave(frame_bits, superframe_bits+i, 2, 156, 1);
/* De-FEC */
err[0] = ir77_ambe_golay24_decode(&frame[ 0], &frame_bits[ 0], &seed);
ir77_ambe_scramble(&frame_bits[24], &frame_bits[24], 156-24-33, seed);
err[1] = ir77_ambe_golay23_decode (&frame[12], &frame_bits[ 24], NULL);
err[2] = ir77_ambe_golay23_decode (&frame[24], &frame_bits[ 47], NULL);
err[3] = ir77_ambe_golay23_decode (&frame[36], &frame_bits[ 70], NULL);
err[4] = ir77_ambe_hamming1511_decode(&frame[48], &frame_bits[ 93]);
err[5] = ir77_ambe_hamming1511_decode(&frame[59], &frame_bits[108]);
memcpy(&frame[70], &frame_bits[123], 33);
/* Skip bad frames */
if ((err[1] + err[2] + err[3]) > 6) {
memset(&audio[360*i], 0x0, sizeof(int16_t) * 360);
continue;
}
/* De-prioritize */
ir77_ambe_prioritize(frame_lin, frame, 1);
/* Classify frame */
type = ir77_ambe_frame_classify(frame_lin);
/* Decode appropriately */
switch (type)
{
case AMBE_SPEECH:
ir77_ambe_decode_speech(dec, &audio[360*i], 360, frame_lin);
break;
case AMBE_TONE:
ir77_ambe_decode_tone(dec, &audio[360*i], 360, frame_lin);
break;
case AMBE_SILENCE:
case AMBE_INVALID:
memset(&audio[360*i], 0x0, sizeof(int16_t) * 360);
break;
}
}
return 0;
}
/*! @} */
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