Mon Jun 27 16:51:12 2011

Asterisk developer's documentation


codec_lpc10.c File Reference

Translate between signed linear and LPC10 (Linear Predictor Code). More...

#include "asterisk.h"
#include "asterisk/translate.h"
#include "asterisk/config.h"
#include "asterisk/module.h"
#include "asterisk/utils.h"
#include "lpc10/lpc10.h"
#include "asterisk/slin.h"
#include "ex_lpc10.h"

Go to the source code of this file.

Data Structures

struct  lpc10_coder_pvt

Defines

#define BUFFER_SAMPLES   8000
#define LPC10_BYTES_IN_COMPRESSED_FRAME   (LPC10_BITS_IN_COMPRESSED_FRAME + 7)/8

Functions

static void __reg_module (void)
static void __unreg_module (void)
static void build_bits (unsigned char *c, INT32 *bits)
static void extract_bits (INT32 *bits, unsigned char *c)
static int lintolpc10_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
static struct ast_framelintolpc10_frameout (struct ast_trans_pvt *pvt)
static int load_module (void)
static int lpc10_dec_new (struct ast_trans_pvt *pvt)
static void lpc10_destroy (struct ast_trans_pvt *arg)
static int lpc10_enc_new (struct ast_trans_pvt *pvt)
static int lpc10tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
static int reload (void)
static int unload_module (void)

Variables

static struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "LPC10 2.4kbps Coder/Decoder" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = "8586c2a7d357cb591cc3a6607a8f62d1" , .load = load_module, .unload = unload_module, .reload = reload, }
static struct ast_module_infoast_module_info = &__mod_info
static struct ast_translator lintolpc10
static struct ast_translator lpc10tolin


Detailed Description

Translate between signed linear and LPC10 (Linear Predictor Code).

Definition in file codec_lpc10.c.


Define Documentation

#define BUFFER_SAMPLES   8000

Definition at line 52 of file codec_lpc10.c.

#define LPC10_BYTES_IN_COMPRESSED_FRAME   (LPC10_BITS_IN_COMPRESSED_FRAME + 7)/8

Definition at line 50 of file codec_lpc10.c.

Referenced by lintolpc10_frameout(), and lpc10tolin_framein().


Function Documentation

static void __reg_module ( void   )  [static]

Definition at line 255 of file codec_lpc10.c.

static void __unreg_module ( void   )  [static]

Definition at line 255 of file codec_lpc10.c.

static void build_bits ( unsigned char *  c,
INT32 *  bits 
) [static]

Definition at line 92 of file codec_lpc10.c.

Referenced by lintolpc10_frameout().

00093 {
00094    unsigned char mask=0x80;
00095    int x;
00096    *c = 0;
00097    for (x=0;x<LPC10_BITS_IN_COMPRESSED_FRAME;x++) {
00098       if (bits[x])
00099          *c |= mask;
00100       mask = mask >> 1;
00101       if ((x % 8)==7) {
00102          c++;
00103          *c = 0;
00104          mask = 0x80;
00105       }
00106    }
00107 }

static void extract_bits ( INT32 *  bits,
unsigned char *  c 
) [static]

Definition at line 78 of file codec_lpc10.c.

Referenced by lpc10tolin_framein().

00079 {
00080    int x;
00081    for (x=0;x<LPC10_BITS_IN_COMPRESSED_FRAME;x++) {
00082       if (*c & (0x80 >> (x & 7)))
00083          bits[x] = 1;
00084       else
00085          bits[x] = 0;
00086       if ((x & 7) == 7)
00087          c++;
00088    }
00089 }

static int lintolpc10_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

Definition at line 142 of file codec_lpc10.c.

References ast_log(), lpc10_coder_pvt::buf, BUFFER_SAMPLES, f, LOG_WARNING, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00143 {
00144    struct lpc10_coder_pvt *tmp = pvt->pvt;
00145 
00146    /* Just add the frames to our stream */
00147    if (pvt->samples + f->samples > BUFFER_SAMPLES) {
00148       ast_log(LOG_WARNING, "Out of buffer space\n");
00149       return -1;
00150    }
00151    memcpy(tmp->buf + pvt->samples, f->data.ptr, f->datalen);
00152    pvt->samples += f->samples;
00153    return 0;
00154 }

static struct ast_frame* lintolpc10_frameout ( struct ast_trans_pvt pvt  )  [static]

Definition at line 156 of file codec_lpc10.c.

References ast_trans_frameout(), lpc10_coder_pvt::buf, build_bits(), lpc10_coder_pvt::enc, lpc10_coder_pvt::longer, lpc10_coder_pvt::lpc10, LPC10_BYTES_IN_COMPRESSED_FRAME, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, ast_trans_pvt::samples, and ast_trans_pvt::uc.

00157 {
00158    struct lpc10_coder_pvt *tmp = pvt->pvt;
00159    int x;
00160    int datalen = 0;  /* output frame */
00161    int samples = 0;  /* output samples */
00162    float tmpbuf[LPC10_SAMPLES_PER_FRAME];
00163    INT32 bits[LPC10_BITS_IN_COMPRESSED_FRAME];  /* XXX what ??? */
00164    /* We can't work on anything less than a frame in size */
00165    if (pvt->samples < LPC10_SAMPLES_PER_FRAME)
00166       return NULL;
00167    while (pvt->samples >=  LPC10_SAMPLES_PER_FRAME) {
00168       /* Encode a frame of data */
00169       for (x=0;x<LPC10_SAMPLES_PER_FRAME;x++)
00170          tmpbuf[x] = (float)tmp->buf[x + samples] / 32768.0;
00171       lpc10_encode(tmpbuf, bits, tmp->lpc10.enc);
00172       build_bits(pvt->outbuf.uc + datalen, bits);
00173       datalen += LPC10_BYTES_IN_COMPRESSED_FRAME;
00174       samples += LPC10_SAMPLES_PER_FRAME;
00175       pvt->samples -= LPC10_SAMPLES_PER_FRAME;
00176       /* Use one of the two left over bits to record if this is a 22 or 23 ms frame...
00177          important for IAX use */
00178       tmp->longer = 1 - tmp->longer;
00179    }
00180    /* Move the data at the end of the buffer to the front */
00181    if (pvt->samples)
00182       memmove(tmp->buf, tmp->buf + samples, pvt->samples * 2);
00183    return ast_trans_frameout(pvt, datalen, samples);
00184 }

static int load_module ( void   )  [static]

Definition at line 237 of file codec_lpc10.c.

References AST_MODULE_LOAD_FAILURE, AST_MODULE_LOAD_SUCCESS, ast_register_translator, ast_unregister_translator(), lintolpc10, and lpc10tolin.

00238 {
00239    int res;
00240 
00241    res = ast_register_translator(&lpc10tolin);
00242    if (!res) 
00243       res = ast_register_translator(&lintolpc10);
00244    else
00245       ast_unregister_translator(&lpc10tolin);
00246    if (res)
00247       return AST_MODULE_LOAD_FAILURE;
00248    return AST_MODULE_LOAD_SUCCESS;
00249 }

static int lpc10_dec_new ( struct ast_trans_pvt pvt  )  [static]

Definition at line 71 of file codec_lpc10.c.

References lpc10_coder_pvt::dec, lpc10_coder_pvt::lpc10, and ast_trans_pvt::pvt.

00072 {
00073    struct lpc10_coder_pvt *tmp = pvt->pvt;
00074 
00075    return (tmp->lpc10.dec = create_lpc10_decoder_state()) ? 0 : -1;
00076 }

static void lpc10_destroy ( struct ast_trans_pvt arg  )  [static]

Definition at line 187 of file codec_lpc10.c.

References ast_free, lpc10_coder_pvt::enc, lpc10_coder_pvt::lpc10, and ast_trans_pvt::pvt.

00188 {
00189    struct lpc10_coder_pvt *pvt = arg->pvt;
00190    /* Enc and DEC are both just allocated, so they can be freed */
00191    ast_free(pvt->lpc10.enc);
00192 }

static int lpc10_enc_new ( struct ast_trans_pvt pvt  )  [static]

Definition at line 64 of file codec_lpc10.c.

References lpc10_coder_pvt::enc, lpc10_coder_pvt::lpc10, and ast_trans_pvt::pvt.

00065 {
00066    struct lpc10_coder_pvt *tmp = pvt->pvt;
00067 
00068    return (tmp->lpc10.enc = create_lpc10_encoder_state()) ? 0 : -1;
00069 }

static int lpc10tolin_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

Definition at line 109 of file codec_lpc10.c.

References ast_log(), BUFFER_SAMPLES, ast_trans_pvt::datalen, lpc10_coder_pvt::dec, extract_bits(), f, ast_trans_pvt::i16, len(), LOG_WARNING, lpc10_coder_pvt::lpc10, LPC10_BYTES_IN_COMPRESSED_FRAME, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, and ast_trans_pvt::samples.

00110 {
00111    struct lpc10_coder_pvt *tmp = pvt->pvt;
00112    int16_t *dst = pvt->outbuf.i16;
00113    int len = 0;
00114 
00115    while (len + LPC10_BYTES_IN_COMPRESSED_FRAME <= f->datalen) {
00116       int x;
00117       float tmpbuf[LPC10_SAMPLES_PER_FRAME];
00118       INT32 bits[LPC10_BITS_IN_COMPRESSED_FRAME]; /* XXX see note */
00119       if (pvt->samples + LPC10_SAMPLES_PER_FRAME > BUFFER_SAMPLES) {
00120          ast_log(LOG_WARNING, "Out of buffer space\n");
00121          return -1;
00122       }
00123       extract_bits(bits, f->data.ptr + len);
00124       if (lpc10_decode(bits, tmpbuf, tmp->lpc10.dec)) {
00125          ast_log(LOG_WARNING, "Invalid lpc10 data\n");
00126          return -1;
00127       }
00128       for (x=0;x<LPC10_SAMPLES_PER_FRAME;x++) {
00129          /* Convert to a short between -1.0 and 1.0 */
00130          dst[pvt->samples + x] = (int16_t)(32768.0 * tmpbuf[x]);
00131       }
00132 
00133       pvt->samples += LPC10_SAMPLES_PER_FRAME;
00134       pvt->datalen += 2*LPC10_SAMPLES_PER_FRAME;
00135       len += LPC10_BYTES_IN_COMPRESSED_FRAME;
00136    }
00137    if (len != f->datalen) 
00138       printf("Decoded %d, expected %d\n", len, f->datalen);
00139    return 0;
00140 }

static int reload ( void   )  [static]

Definition at line 221 of file codec_lpc10.c.

References AST_MODULE_LOAD_SUCCESS.

00222 {
00223    return AST_MODULE_LOAD_SUCCESS;
00224 }

static int unload_module ( void   )  [static]

Definition at line 227 of file codec_lpc10.c.

References ast_unregister_translator(), lintolpc10, and lpc10tolin.

00228 {
00229    int res;
00230 
00231    res = ast_unregister_translator(&lintolpc10);
00232    res |= ast_unregister_translator(&lpc10tolin);
00233 
00234    return res;
00235 }


Variable Documentation

struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "LPC10 2.4kbps Coder/Decoder" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = "8586c2a7d357cb591cc3a6607a8f62d1" , .load = load_module, .unload = unload_module, .reload = reload, } [static]

Definition at line 255 of file codec_lpc10.c.

struct ast_module_info* ast_module_info = &__mod_info [static]

Definition at line 255 of file codec_lpc10.c.

struct ast_translator lintolpc10 [static]

Definition at line 207 of file codec_lpc10.c.

Referenced by load_module(), and unload_module().

struct ast_translator lpc10tolin [static]

Definition at line 194 of file codec_lpc10.c.

Referenced by load_module(), and unload_module().


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