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286 lines
7.0 KiB
C
286 lines
7.0 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 1999 - 2005, Digium, Inc.
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*
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* Mark Spencer <markster@digium.com>
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*
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* The lpc10 code is from a library used by nautilus, modified to be a bit
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* nicer to the compiler.
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* See http://www.arl.wustl.edu/~jaf/
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief Translate between signed linear and LPC10 (Linear Predictor Code)
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*
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* \ingroup codecs
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*/
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/*** MODULEINFO
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<support_level>core</support_level>
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***/
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#include "asterisk.h"
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#include "asterisk/translate.h"
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#include "asterisk/config.h"
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#include "asterisk/module.h"
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#include "asterisk/utils.h"
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#include "asterisk/linkedlists.h"
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#include "lpc10/lpc10.h"
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/* Sample frame data */
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#include "asterisk/slin.h"
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#include "ex_lpc10.h"
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/* We use a very strange format here... I have no idea why... The frames are 180
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samples long, which isn't even an even number of milliseconds... Not only that
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but we hvae to waste two bits of each frame to keep them ending on a byte boundary
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because the frames are 54 bits long */
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#define LPC10_BYTES_IN_COMPRESSED_FRAME (LPC10_BITS_IN_COMPRESSED_FRAME + 7)/8
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#define BUFFER_SAMPLES 8000
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struct lpc10_coder_pvt {
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union {
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struct lpc10_encoder_state *enc;
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struct lpc10_decoder_state *dec;
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} lpc10;
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/* Enough to store a full second */
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short buf[BUFFER_SAMPLES];
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int longer;
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};
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static int lpc10_enc_new(struct ast_trans_pvt *pvt)
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{
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struct lpc10_coder_pvt *tmp = pvt->pvt;
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return (tmp->lpc10.enc = create_lpc10_encoder_state()) ? 0 : -1;
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}
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static int lpc10_dec_new(struct ast_trans_pvt *pvt)
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{
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struct lpc10_coder_pvt *tmp = pvt->pvt;
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return (tmp->lpc10.dec = create_lpc10_decoder_state()) ? 0 : -1;
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}
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static void extract_bits(INT32 *bits, unsigned char *c)
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{
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int x;
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for (x=0;x<LPC10_BITS_IN_COMPRESSED_FRAME;x++) {
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if (*c & (0x80 >> (x & 7)))
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bits[x] = 1;
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else
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bits[x] = 0;
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if ((x & 7) == 7)
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c++;
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}
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}
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/* XXX note lpc10_encode() produces one bit per word in bits[] */
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static void build_bits(unsigned char *c, INT32 *bits)
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{
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unsigned char mask=0x80;
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int x;
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*c = 0;
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for (x=0;x<LPC10_BITS_IN_COMPRESSED_FRAME;x++) {
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if (bits[x])
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*c |= mask;
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mask = mask >> 1;
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if ((x % 8)==7) {
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c++;
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*c = 0;
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mask = 0x80;
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}
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}
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}
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static int lpc10tolin_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
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{
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struct lpc10_coder_pvt *tmp = pvt->pvt;
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int16_t *dst = pvt->outbuf.i16;
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int len = 0;
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while (len + LPC10_BYTES_IN_COMPRESSED_FRAME <= f->datalen) {
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int x;
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float tmpbuf[LPC10_SAMPLES_PER_FRAME];
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INT32 bits[LPC10_BITS_IN_COMPRESSED_FRAME]; /* XXX see note */
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if (pvt->samples + LPC10_SAMPLES_PER_FRAME > BUFFER_SAMPLES) {
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ast_log(LOG_WARNING, "Out of buffer space\n");
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return -1;
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}
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extract_bits(bits, f->data.ptr + len);
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if (lpc10_decode(bits, tmpbuf, tmp->lpc10.dec)) {
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ast_log(LOG_WARNING, "Invalid lpc10 data\n");
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return -1;
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}
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for (x=0;x<LPC10_SAMPLES_PER_FRAME;x++) {
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/* Convert to a short between -1.0 and 1.0 */
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dst[pvt->samples + x] = (int16_t)(32768.0 * tmpbuf[x]);
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}
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pvt->samples += LPC10_SAMPLES_PER_FRAME;
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pvt->datalen += 2*LPC10_SAMPLES_PER_FRAME;
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len += LPC10_BYTES_IN_COMPRESSED_FRAME;
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}
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if (len != f->datalen)
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printf("Decoded %d, expected %d\n", len, f->datalen);
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return 0;
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}
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static int lintolpc10_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
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{
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struct lpc10_coder_pvt *tmp = pvt->pvt;
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/* Just add the frames to our stream */
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if (pvt->samples + f->samples > BUFFER_SAMPLES) {
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ast_log(LOG_WARNING, "Out of buffer space\n");
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return -1;
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}
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memcpy(tmp->buf + pvt->samples, f->data.ptr, f->datalen);
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pvt->samples += f->samples;
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return 0;
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}
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static struct ast_frame *lintolpc10_frameout(struct ast_trans_pvt *pvt)
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{
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struct lpc10_coder_pvt *tmp = pvt->pvt;
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struct ast_frame *result = NULL;
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struct ast_frame *last = NULL;
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int samples = 0; /* output samples */
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while (pvt->samples >= LPC10_SAMPLES_PER_FRAME) {
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struct ast_frame *current;
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float tmpbuf[LPC10_SAMPLES_PER_FRAME];
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INT32 bits[LPC10_BITS_IN_COMPRESSED_FRAME]; /* XXX what ??? */
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int x;
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/* Encode a frame of data */
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for (x=0;x<LPC10_SAMPLES_PER_FRAME;x++)
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tmpbuf[x] = (float)tmp->buf[x + samples] / 32768.0;
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lpc10_encode(tmpbuf, bits, tmp->lpc10.enc);
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build_bits(pvt->outbuf.uc, bits);
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samples += LPC10_SAMPLES_PER_FRAME;
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pvt->samples -= LPC10_SAMPLES_PER_FRAME;
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/* Use one of the two left over bits to record if this is a 22 or 23 ms frame...
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important for IAX use */
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tmp->longer = 1 - tmp->longer;
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current = ast_trans_frameout(pvt, LPC10_BYTES_IN_COMPRESSED_FRAME, LPC10_SAMPLES_PER_FRAME);
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if (!current) {
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continue;
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} else if (last) {
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AST_LIST_NEXT(last, frame_list) = current;
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} else {
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result = current;
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}
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last = current;
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}
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/* Move the data at the end of the buffer to the front */
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if (samples) {
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memmove(tmp->buf, tmp->buf + samples, pvt->samples * 2);
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}
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return result;
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}
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static void lpc10_destroy(struct ast_trans_pvt *arg)
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{
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struct lpc10_coder_pvt *pvt = arg->pvt;
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/* Enc and DEC are both just allocated, so they can be freed */
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ast_free(pvt->lpc10.enc);
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}
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static struct ast_translator lpc10tolin = {
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.name = "lpc10tolin",
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.src_codec = {
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.name = "lpc10",
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.type = AST_MEDIA_TYPE_AUDIO,
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.sample_rate = 8000,
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},
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.dst_codec = {
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.name = "slin",
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.type = AST_MEDIA_TYPE_AUDIO,
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.sample_rate = 8000,
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},
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.format = "slin",
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.newpvt = lpc10_dec_new,
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.framein = lpc10tolin_framein,
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.destroy = lpc10_destroy,
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.sample = lpc10_sample,
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.desc_size = sizeof(struct lpc10_coder_pvt),
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.buffer_samples = BUFFER_SAMPLES,
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.buf_size = BUFFER_SAMPLES * 2,
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};
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static struct ast_translator lintolpc10 = {
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.name = "lintolpc10",
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.src_codec = {
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.name = "slin",
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.type = AST_MEDIA_TYPE_AUDIO,
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.sample_rate = 8000,
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},
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.dst_codec = {
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.name = "lpc10",
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.type = AST_MEDIA_TYPE_AUDIO,
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.sample_rate = 8000,
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},
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.format = "lpc10",
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.newpvt = lpc10_enc_new,
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.framein = lintolpc10_framein,
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.frameout = lintolpc10_frameout,
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.destroy = lpc10_destroy,
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.sample = slin8_sample,
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.desc_size = sizeof(struct lpc10_coder_pvt),
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.buffer_samples = BUFFER_SAMPLES,
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.buf_size = LPC10_BYTES_IN_COMPRESSED_FRAME * (1 + BUFFER_SAMPLES / LPC10_SAMPLES_PER_FRAME),
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};
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static int unload_module(void)
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{
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int res;
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res = ast_unregister_translator(&lintolpc10);
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res |= ast_unregister_translator(&lpc10tolin);
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return res;
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}
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static int load_module(void)
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{
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int res;
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res = ast_register_translator(&lpc10tolin);
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res |= ast_register_translator(&lintolpc10);
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if (res) {
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unload_module();
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return AST_MODULE_LOAD_DECLINE;
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}
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return AST_MODULE_LOAD_SUCCESS;
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}
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AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "LPC10 2.4kbps Coder/Decoder",
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.support_level = AST_MODULE_SUPPORT_CORE,
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.load = load_module,
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.unload = unload_module,
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);
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