Sat Aug 6 00:39:28 2011

Asterisk developer's documentation


format_pcm.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2006, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  *
00021  * \brief Flat, binary, ulaw PCM file format.
00022  * \arg File name extension: pcm, ulaw, ul, mu
00023  * 
00024  * \ingroup formats
00025  */
00026  
00027 #include "asterisk.h"
00028 
00029 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 233782 $")
00030 
00031 #include <unistd.h>
00032 #include <netinet/in.h>
00033 #include <arpa/inet.h>
00034 #include <stdlib.h>
00035 #include <sys/time.h>
00036 #include <stdio.h>
00037 #include <errno.h>
00038 #include <string.h>
00039 
00040 #include "asterisk/lock.h"
00041 #include "asterisk/channel.h"
00042 #include "asterisk/file.h"
00043 #include "asterisk/logger.h"
00044 #include "asterisk/sched.h"
00045 #include "asterisk/module.h"
00046 #include "asterisk/endian.h"
00047 #include "asterisk/ulaw.h"
00048 #include "asterisk/alaw.h"
00049 
00050 #define BUF_SIZE 160    /* 160 bytes, and same number of samples */
00051 
00052 static char ulaw_silence[BUF_SIZE];
00053 static char alaw_silence[BUF_SIZE];
00054 
00055 /* #define REALTIME_WRITE */  /* XXX does it work at all ? */
00056 
00057 #ifdef REALTIME_WRITE
00058 struct pcm_desc {
00059    unsigned long start_time;
00060 };
00061 
00062 /* Returns time in msec since system boot. */
00063 static unsigned long get_time(void)
00064 {
00065    struct tms buf;
00066    clock_t cur;
00067 
00068    cur = times( &buf );
00069    if( cur < 0 ) {
00070       ast_log( LOG_WARNING, "Cannot get current time\n" );
00071       return 0;
00072    }
00073    return cur * 1000 / sysconf( _SC_CLK_TCK );
00074 }
00075 
00076 static int pcma_open(struct ast_filestream *s)
00077 {
00078    if (s->fmt->format == AST_FORMAT_ALAW)
00079       pd->starttime = get_time();
00080    return 0;
00081 }
00082 
00083 static int pcma_rewrite(struct ast_filestream *s, const char *comment)
00084 {
00085    return pcma_open(s);
00086 }
00087 #endif
00088 
00089 static struct ast_frame *pcm_read(struct ast_filestream *s, int *whennext)
00090 {
00091    int res;
00092    
00093    /* Send a frame from the file to the appropriate channel */
00094 
00095    s->fr.frametype = AST_FRAME_VOICE;
00096    s->fr.subclass = s->fmt->format;
00097    s->fr.mallocd = 0;
00098    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00099    if ((res = fread(s->fr.data, 1, s->fr.datalen, s->f)) < 1) {
00100       if (res)
00101          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00102       return NULL;
00103    }
00104    s->fr.datalen = res;
00105    if (s->fmt->format == AST_FORMAT_G722)
00106       *whennext = s->fr.samples = res * 2;
00107    else
00108       *whennext = s->fr.samples = res;
00109    return &s->fr;
00110 }
00111 
00112 static int pcm_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00113 {
00114    off_t cur, max, offset = 0;
00115    int ret = -1;  /* assume error */
00116 
00117    cur = ftello(fs->f);
00118    fseeko(fs->f, 0, SEEK_END);
00119    max = ftello(fs->f);
00120 
00121    switch (whence) {
00122    case SEEK_SET:
00123       offset = sample_offset;
00124       break;
00125    case SEEK_END:
00126       offset = max - sample_offset;
00127       break;
00128    case SEEK_CUR:
00129    case SEEK_FORCECUR:
00130       offset = cur + sample_offset;
00131       break;
00132    default:
00133       ast_log(LOG_WARNING, "invalid whence %d, assuming SEEK_SET\n", whence);
00134       offset = sample_offset;
00135    }
00136    if (offset < 0) {
00137       ast_log(LOG_WARNING, "negative offset %ld, resetting to 0\n", (long) offset);
00138       offset = 0;
00139    }
00140    if (whence == SEEK_FORCECUR && offset > max) { /* extend the file */
00141       size_t left = offset - max;
00142       const char *src = (fs->fmt->format == AST_FORMAT_ALAW) ? alaw_silence : ulaw_silence;
00143 
00144       while (left) {
00145          size_t written = fwrite(src, 1, (left > BUF_SIZE) ? BUF_SIZE : left, fs->f);
00146          if (written == -1)
00147             break;   /* error */
00148          left -= written;
00149       }
00150       ret = 0; /* successful */
00151    } else {
00152       if (offset > max) {
00153          ast_log(LOG_WARNING, "offset too large %ld, truncating to %ld\n", (long) offset, (long) max);
00154          offset = max;
00155       }
00156       ret = fseeko(fs->f, offset, SEEK_SET);
00157    }
00158    return ret;
00159 }
00160 
00161 static int pcm_trunc(struct ast_filestream *fs)
00162 {
00163    return ftruncate(fileno(fs->f), ftello(fs->f));
00164 }
00165 
00166 static off_t pcm_tell(struct ast_filestream *fs)
00167 {
00168    return ftello(fs->f);
00169 }
00170 
00171 static int pcm_write(struct ast_filestream *fs, struct ast_frame *f)
00172 {
00173    int res;
00174 
00175    if (f->frametype != AST_FRAME_VOICE) {
00176       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00177       return -1;
00178    }
00179    if (f->subclass != fs->fmt->format) {
00180       ast_log(LOG_WARNING, "Asked to write incompatible format frame (%d)!\n", f->subclass);
00181       return -1;
00182    }
00183 
00184 #ifdef REALTIME_WRITE
00185    if (s->fmt->format == AST_FORMAT_ALAW) {
00186       struct pcm_desc *pd = (struct pcm_desc *)fs->_private;
00187       struct stat stat_buf;
00188       unsigned long cur_time = get_time();
00189       unsigned long fpos = ( cur_time - pd->start_time ) * 8;  /* 8 bytes per msec */
00190       /* Check if we have written to this position yet. If we have, then increment pos by one frame
00191       *  for some degree of protection against receiving packets in the same clock tick.
00192       */
00193       
00194       fstat(fileno(fs->f), &stat_buf );
00195       if (stat_buf.st_size > fpos )
00196          fpos += f->datalen;  /* Incrementing with the size of this current frame */
00197 
00198       if (stat_buf.st_size < fpos) {
00199          /* fill the gap with 0x55 rather than 0. */
00200          char buf[1024];
00201          unsigned long cur, to_write;
00202 
00203          cur = stat_buf.st_size;
00204          if (fseek(fs->f, cur, SEEK_SET) < 0) {
00205             ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
00206             return -1;
00207          }
00208          memset(buf, 0x55, 512);
00209          while (cur < fpos) {
00210             to_write = fpos - cur;
00211             if (to_write > sizeof(buf))
00212                to_write = sizeof(buf);
00213             fwrite(buf, 1, to_write, fs->f);
00214             cur += to_write;
00215          }
00216       }
00217 
00218       if (fseek(s->f, fpos, SEEK_SET) < 0) {
00219          ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
00220          return -1;
00221       }
00222    }
00223 #endif   /* REALTIME_WRITE */
00224    
00225    if ((res = fwrite(f->data, 1, f->datalen, fs->f)) != f->datalen) {
00226       ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00227       return -1;
00228    }
00229    return 0;
00230 }
00231 
00232 /* SUN .au support routines */
00233 
00234 #define AU_HEADER_SIZE     24
00235 #define AU_HEADER(var)     uint32_t var[6]
00236 
00237 #define AU_HDR_MAGIC_OFF   0
00238 #define AU_HDR_HDR_SIZE_OFF   1
00239 #define AU_HDR_DATA_SIZE_OFF  2
00240 #define AU_HDR_ENCODING_OFF   3
00241 #define AU_HDR_SAMPLE_RATE_OFF   4
00242 #define AU_HDR_CHANNELS_OFF   5
00243 
00244 #define AU_ENC_8BIT_ULAW   1
00245 
00246 #define AU_MAGIC 0x2e736e64
00247 #if __BYTE_ORDER == __BIG_ENDIAN
00248 #define htoll(b) (b)
00249 #define htols(b) (b)
00250 #define ltohl(b) (b)
00251 #define ltohs(b) (b)
00252 #else
00253 #if __BYTE_ORDER == __LITTLE_ENDIAN
00254 #define htoll(b)  \
00255           (((((b)      ) & 0xFF) << 24) | \
00256           ((((b) >>  8) & 0xFF) << 16) | \
00257          ((((b) >> 16) & 0xFF) <<  8) | \
00258          ((((b) >> 24) & 0xFF)      ))
00259 #define htols(b) \
00260           (((((b)      ) & 0xFF) << 8) | \
00261          ((((b) >> 8) & 0xFF)      ))
00262 #define ltohl(b) htoll(b)
00263 #define ltohs(b) htols(b)
00264 #else
00265 #error "Endianess not defined"
00266 #endif
00267 #endif
00268 
00269 static int check_header(FILE *f)
00270 {
00271    AU_HEADER(header);
00272    uint32_t magic;
00273    uint32_t hdr_size;
00274    uint32_t data_size;
00275    uint32_t encoding;
00276    uint32_t sample_rate;
00277    uint32_t channels;
00278 
00279    if (fread(header, 1, AU_HEADER_SIZE, f) != AU_HEADER_SIZE) {
00280       ast_log(LOG_WARNING, "Read failed (header)\n");
00281       return -1;
00282    }
00283    magic = ltohl(header[AU_HDR_MAGIC_OFF]);
00284    if (magic != (uint32_t) AU_MAGIC) {
00285       ast_log(LOG_WARNING, "Bad magic: 0x%x\n", magic);
00286    }
00287    hdr_size = ltohl(header[AU_HDR_HDR_SIZE_OFF]);
00288    if (hdr_size < AU_HEADER_SIZE) {
00289       hdr_size = AU_HEADER_SIZE;
00290    }
00291 /* data_size = ltohl(header[AU_HDR_DATA_SIZE_OFF]); */
00292    encoding = ltohl(header[AU_HDR_ENCODING_OFF]);
00293    if (encoding != AU_ENC_8BIT_ULAW) {
00294       ast_log(LOG_WARNING, "Unexpected format: %d. Only 8bit ULAW allowed (%d)\n", encoding, AU_ENC_8BIT_ULAW);
00295       return -1;
00296    }
00297    sample_rate = ltohl(header[AU_HDR_SAMPLE_RATE_OFF]);
00298    if (sample_rate != DEFAULT_SAMPLE_RATE) {
00299       ast_log(LOG_WARNING, "Sample rate can only be 8000 not %d\n", sample_rate);
00300       return -1;
00301    }
00302    channels = ltohl(header[AU_HDR_CHANNELS_OFF]);
00303    if (channels != 1) {
00304       ast_log(LOG_WARNING, "Not in mono: channels=%d\n", channels);
00305       return -1;
00306    }
00307    /* Skip to data */
00308    fseek(f, 0, SEEK_END);
00309    data_size = ftell(f) - hdr_size;
00310    if (fseek(f, hdr_size, SEEK_SET) == -1 ) {
00311       ast_log(LOG_WARNING, "Failed to skip to data: %d\n", hdr_size);
00312       return -1;
00313    }
00314    return data_size;
00315 }
00316 
00317 static int update_header(FILE *f)
00318 {
00319    off_t cur, end;
00320    uint32_t datalen;
00321    int bytes;
00322 
00323    cur = ftell(f);
00324    fseek(f, 0, SEEK_END);
00325    end = ftell(f);
00326    /* data starts 24 bytes in */
00327    bytes = end - AU_HEADER_SIZE;
00328    datalen = htoll(bytes);
00329 
00330    if (cur < 0) {
00331       ast_log(LOG_WARNING, "Unable to find our position\n");
00332       return -1;
00333    }
00334    if (fseek(f, AU_HDR_DATA_SIZE_OFF * sizeof(uint32_t), SEEK_SET)) {
00335       ast_log(LOG_WARNING, "Unable to set our position\n");
00336       return -1;
00337    }
00338    if (fwrite(&datalen, 1, sizeof(datalen), f) != sizeof(datalen)) {
00339       ast_log(LOG_WARNING, "Unable to set write file size\n");
00340       return -1;
00341    }
00342    if (fseek(f, cur, SEEK_SET)) {
00343       ast_log(LOG_WARNING, "Unable to return to position\n");
00344       return -1;
00345    }
00346    return 0;
00347 }
00348 
00349 static int write_header(FILE *f)
00350 {
00351    AU_HEADER(header);
00352 
00353    header[AU_HDR_MAGIC_OFF] = htoll((uint32_t) AU_MAGIC);
00354    header[AU_HDR_HDR_SIZE_OFF] = htoll(AU_HEADER_SIZE);
00355    header[AU_HDR_DATA_SIZE_OFF] = 0;
00356    header[AU_HDR_ENCODING_OFF] = htoll(AU_ENC_8BIT_ULAW);
00357    header[AU_HDR_SAMPLE_RATE_OFF] = htoll(DEFAULT_SAMPLE_RATE);
00358    header[AU_HDR_CHANNELS_OFF] = htoll(1);
00359 
00360    /* Write an au header, ignoring sizes which will be filled in later */
00361    fseek(f, 0, SEEK_SET);
00362    if (fwrite(header, 1, AU_HEADER_SIZE, f) != AU_HEADER_SIZE) {
00363       ast_log(LOG_WARNING, "Unable to write header\n");
00364       return -1;
00365    }
00366    return 0;
00367 }
00368 
00369 static int au_open(struct ast_filestream *s)
00370 {
00371    if (check_header(s->f) < 0)
00372       return -1;
00373    return 0;
00374 }
00375 
00376 static int au_rewrite(struct ast_filestream *s, const char *comment)
00377 {
00378    if (write_header(s->f))
00379       return -1;
00380    return 0;
00381 }
00382 
00383 /* XXX check this, probably incorrect */
00384 static int au_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00385 {
00386    off_t min, max, cur;
00387    long offset = 0, bytes;
00388 
00389    if (fs->fmt->format == AST_FORMAT_G722)
00390       bytes = sample_offset / 2;
00391    else
00392       bytes = sample_offset;
00393 
00394    min = AU_HEADER_SIZE;
00395    cur = ftello(fs->f);
00396    fseek(fs->f, 0, SEEK_END);
00397    max = ftello(fs->f);
00398 
00399    if (whence == SEEK_SET)
00400       offset = bytes + min;
00401    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00402       offset = bytes + cur;
00403    else if (whence == SEEK_END)
00404       offset = max - bytes;
00405         if (whence != SEEK_FORCECUR) {
00406       offset = (offset > max) ? max : offset;
00407    }
00408 
00409    /* always protect the header space. */
00410    offset = (offset < min) ? min : offset;
00411 
00412    return fseeko(fs->f, offset, SEEK_SET);
00413 }
00414 
00415 static int au_trunc(struct ast_filestream *fs)
00416 {
00417    if (ftruncate(fileno(fs->f), ftell(fs->f)))
00418       return -1;
00419    return update_header(fs->f);
00420 }
00421 
00422 static off_t au_tell(struct ast_filestream *fs)
00423 {
00424    off_t offset = ftello(fs->f);
00425    return offset - AU_HEADER_SIZE;
00426 }
00427 
00428 static const struct ast_format alaw_f = {
00429    .name = "alaw",
00430    .exts = "alaw|al",
00431    .format = AST_FORMAT_ALAW,
00432    .write = pcm_write,
00433    .seek = pcm_seek,
00434    .trunc = pcm_trunc,
00435    .tell = pcm_tell,
00436    .read = pcm_read,
00437    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00438 #ifdef REALTIME_WRITE
00439    .open = pcma_open,
00440    .rewrite = pcma_rewrite,
00441    .desc_size = sizeof(struct pcm_desc),
00442 #endif
00443 };
00444 
00445 static const struct ast_format pcm_f = {
00446    .name = "pcm",
00447    .exts = "pcm|ulaw|ul|mu",
00448    .format = AST_FORMAT_ULAW,
00449    .write = pcm_write,
00450    .seek = pcm_seek,
00451    .trunc = pcm_trunc,
00452    .tell = pcm_tell,
00453    .read = pcm_read,
00454    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00455 };
00456 
00457 static const struct ast_format g722_f = {
00458    .name = "g722",
00459    .exts = "g722",
00460    .format = AST_FORMAT_G722,
00461    .write = pcm_write,
00462    .seek = pcm_seek,
00463    .trunc = pcm_trunc,
00464    .tell = pcm_tell,
00465    .read = pcm_read,
00466    .buf_size = (BUF_SIZE * 2) + AST_FRIENDLY_OFFSET,
00467 };
00468 
00469 static const struct ast_format au_f = {
00470    .name = "au",
00471    .exts = "au",
00472    .format = AST_FORMAT_ULAW,
00473    .open = au_open,
00474    .rewrite = au_rewrite,
00475    .write = pcm_write,
00476    .seek = au_seek,
00477    .trunc = au_trunc,
00478    .tell = au_tell,
00479    .read = pcm_read,
00480    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,  /* this many shorts */
00481 };
00482 
00483 static int load_module(void)
00484 {
00485    int index;
00486 
00487    /* XXX better init ? */
00488    for (index = 0; index < (sizeof(ulaw_silence) / sizeof(ulaw_silence[0])); index++)
00489       ulaw_silence[index] = AST_LIN2MU(0);
00490    for (index = 0; index < (sizeof(alaw_silence) / sizeof(alaw_silence[0])); index++)
00491       alaw_silence[index] = AST_LIN2A(0);
00492 
00493    return ast_format_register(&pcm_f)
00494       || ast_format_register(&alaw_f)
00495       || ast_format_register(&au_f)
00496       || ast_format_register(&g722_f);
00497 }
00498 
00499 static int unload_module(void)
00500 {
00501    return ast_format_unregister(pcm_f.name)
00502       || ast_format_unregister(alaw_f.name)
00503       || ast_format_unregister(au_f.name)
00504       || ast_format_unregister(g722_f.name);
00505 }  
00506 
00507 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_FIRST, "Raw/Sun uLaw/ALaw 8KHz (PCM,PCMA,AU), G.722 16Khz",
00508    .load = load_module,
00509    .unload = unload_module,
00510 );

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