Fri Sep 25 19:28:11 2009

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: 90155 $")
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    *whennext = s->fr.samples = res;
00106    return &s->fr;
00107 }
00108 
00109 static int pcm_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00110 {
00111    off_t cur, max, offset = 0;
00112    int ret = -1;  /* assume error */
00113 
00114    cur = ftello(fs->f);
00115    fseeko(fs->f, 0, SEEK_END);
00116    max = ftello(fs->f);
00117 
00118    switch (whence) {
00119    case SEEK_SET:
00120       offset = sample_offset;
00121       break;
00122    case SEEK_END:
00123       offset = max - sample_offset;
00124       break;
00125    case SEEK_CUR:
00126    case SEEK_FORCECUR:
00127       offset = cur + sample_offset;
00128       break;
00129    default:
00130       ast_log(LOG_WARNING, "invalid whence %d, assuming SEEK_SET\n", whence);
00131       offset = sample_offset;
00132    }
00133    if (offset < 0) {
00134       ast_log(LOG_WARNING, "negative offset %ld, resetting to 0\n", (long) offset);
00135       offset = 0;
00136    }
00137    if (whence == SEEK_FORCECUR && offset > max) { /* extend the file */
00138       size_t left = offset - max;
00139       const char *src = (fs->fmt->format == AST_FORMAT_ALAW) ? alaw_silence : ulaw_silence;
00140 
00141       while (left) {
00142          size_t written = fwrite(src, 1, (left > BUF_SIZE) ? BUF_SIZE : left, fs->f);
00143          if (written == -1)
00144             break;   /* error */
00145          left -= written;
00146       }
00147       ret = 0; /* successful */
00148    } else {
00149       if (offset > max) {
00150          ast_log(LOG_WARNING, "offset too large %ld, truncating to %ld\n", (long) offset, (long) max);
00151          offset = max;
00152       }
00153       ret = fseeko(fs->f, offset, SEEK_SET);
00154    }
00155    return ret;
00156 }
00157 
00158 static int pcm_trunc(struct ast_filestream *fs)
00159 {
00160    return ftruncate(fileno(fs->f), ftello(fs->f));
00161 }
00162 
00163 static off_t pcm_tell(struct ast_filestream *fs)
00164 {
00165    return ftello(fs->f);
00166 }
00167 
00168 static int pcm_write(struct ast_filestream *fs, struct ast_frame *f)
00169 {
00170    int res;
00171 
00172    if (f->frametype != AST_FRAME_VOICE) {
00173       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00174       return -1;
00175    }
00176    if (f->subclass != fs->fmt->format) {
00177       ast_log(LOG_WARNING, "Asked to write incompatible format frame (%d)!\n", f->subclass);
00178       return -1;
00179    }
00180 
00181 #ifdef REALTIME_WRITE
00182    if (s->fmt->format == AST_FORMAT_ALAW) {
00183       struct pcm_desc *pd = (struct pcm_desc *)fs->_private;
00184       struct stat stat_buf;
00185       unsigned long cur_time = get_time();
00186       unsigned long fpos = ( cur_time - pd->start_time ) * 8;  /* 8 bytes per msec */
00187       /* Check if we have written to this position yet. If we have, then increment pos by one frame
00188       *  for some degree of protection against receiving packets in the same clock tick.
00189       */
00190       
00191       fstat(fileno(fs->f), &stat_buf );
00192       if (stat_buf.st_size > fpos )
00193          fpos += f->datalen;  /* Incrementing with the size of this current frame */
00194 
00195       if (stat_buf.st_size < fpos) {
00196          /* fill the gap with 0x55 rather than 0. */
00197          char buf[1024];
00198          unsigned long cur, to_write;
00199 
00200          cur = stat_buf.st_size;
00201          if (fseek(fs->f, cur, SEEK_SET) < 0) {
00202             ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
00203             return -1;
00204          }
00205          memset(buf, 0x55, 512);
00206          while (cur < fpos) {
00207             to_write = fpos - cur;
00208             if (to_write > sizeof(buf))
00209                to_write = sizeof(buf);
00210             fwrite(buf, 1, to_write, fs->f);
00211             cur += to_write;
00212          }
00213       }
00214 
00215       if (fseek(s->f, fpos, SEEK_SET) < 0) {
00216          ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
00217          return -1;
00218       }
00219    }
00220 #endif   /* REALTIME_WRITE */
00221    
00222    if ((res = fwrite(f->data, 1, f->datalen, fs->f)) != f->datalen) {
00223       ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00224       return -1;
00225    }
00226    return 0;
00227 }
00228 
00229 /* SUN .au support routines */
00230 
00231 #define AU_HEADER_SIZE     24
00232 #define AU_HEADER(var)     uint32_t var[6]
00233 
00234 #define AU_HDR_MAGIC_OFF   0
00235 #define AU_HDR_HDR_SIZE_OFF   1
00236 #define AU_HDR_DATA_SIZE_OFF  2
00237 #define AU_HDR_ENCODING_OFF   3
00238 #define AU_HDR_SAMPLE_RATE_OFF   4
00239 #define AU_HDR_CHANNELS_OFF   5
00240 
00241 #define AU_ENC_8BIT_ULAW   1
00242 
00243 #define AU_MAGIC 0x2e736e64
00244 #if __BYTE_ORDER == __BIG_ENDIAN
00245 #define htoll(b) (b)
00246 #define htols(b) (b)
00247 #define ltohl(b) (b)
00248 #define ltohs(b) (b)
00249 #else
00250 #if __BYTE_ORDER == __LITTLE_ENDIAN
00251 #define htoll(b)  \
00252           (((((b)      ) & 0xFF) << 24) | \
00253           ((((b) >>  8) & 0xFF) << 16) | \
00254          ((((b) >> 16) & 0xFF) <<  8) | \
00255          ((((b) >> 24) & 0xFF)      ))
00256 #define htols(b) \
00257           (((((b)      ) & 0xFF) << 8) | \
00258          ((((b) >> 8) & 0xFF)      ))
00259 #define ltohl(b) htoll(b)
00260 #define ltohs(b) htols(b)
00261 #else
00262 #error "Endianess not defined"
00263 #endif
00264 #endif
00265 
00266 static int check_header(FILE *f)
00267 {
00268    AU_HEADER(header);
00269    uint32_t magic;
00270    uint32_t hdr_size;
00271    uint32_t data_size;
00272    uint32_t encoding;
00273    uint32_t sample_rate;
00274    uint32_t channels;
00275 
00276    if (fread(header, 1, AU_HEADER_SIZE, f) != AU_HEADER_SIZE) {
00277       ast_log(LOG_WARNING, "Read failed (header)\n");
00278       return -1;
00279    }
00280    magic = ltohl(header[AU_HDR_MAGIC_OFF]);
00281    if (magic != (uint32_t) AU_MAGIC) {
00282       ast_log(LOG_WARNING, "Bad magic: 0x%x\n", magic);
00283    }
00284 /* hdr_size = ltohl(header[AU_HDR_HDR_SIZE_OFF]);
00285    if (hdr_size < AU_HEADER_SIZE)*/
00286    hdr_size = AU_HEADER_SIZE;
00287 /* data_size = ltohl(header[AU_HDR_DATA_SIZE_OFF]); */
00288    encoding = ltohl(header[AU_HDR_ENCODING_OFF]);
00289    if (encoding != AU_ENC_8BIT_ULAW) {
00290       ast_log(LOG_WARNING, "Unexpected format: %d. Only 8bit ULAW allowed (%d)\n", encoding, AU_ENC_8BIT_ULAW);
00291       return -1;
00292    }
00293    sample_rate = ltohl(header[AU_HDR_SAMPLE_RATE_OFF]);
00294    if (sample_rate != DEFAULT_SAMPLE_RATE) {
00295       ast_log(LOG_WARNING, "Sample rate can only be 8000 not %d\n", sample_rate);
00296       return -1;
00297    }
00298    channels = ltohl(header[AU_HDR_CHANNELS_OFF]);
00299    if (channels != 1) {
00300       ast_log(LOG_WARNING, "Not in mono: channels=%d\n", channels);
00301       return -1;
00302    }
00303    /* Skip to data */
00304    fseek(f, 0, SEEK_END);
00305    data_size = ftell(f) - hdr_size;
00306    if (fseek(f, hdr_size, SEEK_SET) == -1 ) {
00307       ast_log(LOG_WARNING, "Failed to skip to data: %d\n", hdr_size);
00308       return -1;
00309    }
00310    return data_size;
00311 }
00312 
00313 static int update_header(FILE *f)
00314 {
00315    off_t cur, end;
00316    uint32_t datalen;
00317    int bytes;
00318 
00319    cur = ftell(f);
00320    fseek(f, 0, SEEK_END);
00321    end = ftell(f);
00322    /* data starts 24 bytes in */
00323    bytes = end - AU_HEADER_SIZE;
00324    datalen = htoll(bytes);
00325 
00326    if (cur < 0) {
00327       ast_log(LOG_WARNING, "Unable to find our position\n");
00328       return -1;
00329    }
00330    if (fseek(f, AU_HDR_DATA_SIZE_OFF * sizeof(uint32_t), SEEK_SET)) {
00331       ast_log(LOG_WARNING, "Unable to set our position\n");
00332       return -1;
00333    }
00334    if (fwrite(&datalen, 1, sizeof(datalen), f) != sizeof(datalen)) {
00335       ast_log(LOG_WARNING, "Unable to set write file size\n");
00336       return -1;
00337    }
00338    if (fseek(f, cur, SEEK_SET)) {
00339       ast_log(LOG_WARNING, "Unable to return to position\n");
00340       return -1;
00341    }
00342    return 0;
00343 }
00344 
00345 static int write_header(FILE *f)
00346 {
00347    AU_HEADER(header);
00348 
00349    header[AU_HDR_MAGIC_OFF] = htoll((uint32_t) AU_MAGIC);
00350    header[AU_HDR_HDR_SIZE_OFF] = htoll(AU_HEADER_SIZE);
00351    header[AU_HDR_DATA_SIZE_OFF] = 0;
00352    header[AU_HDR_ENCODING_OFF] = htoll(AU_ENC_8BIT_ULAW);
00353    header[AU_HDR_SAMPLE_RATE_OFF] = htoll(DEFAULT_SAMPLE_RATE);
00354    header[AU_HDR_CHANNELS_OFF] = htoll(1);
00355 
00356    /* Write an au header, ignoring sizes which will be filled in later */
00357    fseek(f, 0, SEEK_SET);
00358    if (fwrite(header, 1, AU_HEADER_SIZE, f) != AU_HEADER_SIZE) {
00359       ast_log(LOG_WARNING, "Unable to write header\n");
00360       return -1;
00361    }
00362    return 0;
00363 }
00364 
00365 static int au_open(struct ast_filestream *s)
00366 {
00367    if (check_header(s->f) < 0)
00368       return -1;
00369    return 0;
00370 }
00371 
00372 static int au_rewrite(struct ast_filestream *s, const char *comment)
00373 {
00374    if (write_header(s->f))
00375       return -1;
00376    return 0;
00377 }
00378 
00379 /* XXX check this, probably incorrect */
00380 static int au_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00381 {
00382    off_t min, max, cur;
00383    long offset = 0, samples;
00384    
00385    samples = sample_offset;
00386    min = AU_HEADER_SIZE;
00387    cur = ftello(fs->f);
00388    fseek(fs->f, 0, SEEK_END);
00389    max = ftello(fs->f);
00390    if (whence == SEEK_SET)
00391       offset = samples + min;
00392    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00393       offset = samples + cur;
00394    else if (whence == SEEK_END)
00395       offset = max - samples;
00396         if (whence != SEEK_FORCECUR) {
00397       offset = (offset > max) ? max : offset;
00398    }
00399    /* always protect the header space. */
00400    offset = (offset < min) ? min : offset;
00401    return fseeko(fs->f, offset, SEEK_SET);
00402 }
00403 
00404 static int au_trunc(struct ast_filestream *fs)
00405 {
00406    if (ftruncate(fileno(fs->f), ftell(fs->f)))
00407       return -1;
00408    return update_header(fs->f);
00409 }
00410 
00411 static off_t au_tell(struct ast_filestream *fs)
00412 {
00413    off_t offset = ftello(fs->f);
00414    return offset - AU_HEADER_SIZE;
00415 }
00416 
00417 static const struct ast_format alaw_f = {
00418    .name = "alaw",
00419    .exts = "alaw|al",
00420    .format = AST_FORMAT_ALAW,
00421    .write = pcm_write,
00422    .seek = pcm_seek,
00423    .trunc = pcm_trunc,
00424    .tell = pcm_tell,
00425    .read = pcm_read,
00426    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00427 #ifdef REALTIME_WRITE
00428    .open = pcma_open,
00429    .rewrite = pcma_rewrite,
00430    .desc_size = sizeof(struct pcm_desc),
00431 #endif
00432 };
00433 
00434 static const struct ast_format pcm_f = {
00435    .name = "pcm",
00436    .exts = "pcm|ulaw|ul|mu",
00437    .format = AST_FORMAT_ULAW,
00438    .write = pcm_write,
00439    .seek = pcm_seek,
00440    .trunc = pcm_trunc,
00441    .tell = pcm_tell,
00442    .read = pcm_read,
00443    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00444 };
00445 
00446 static const struct ast_format g722_f = {
00447    .name = "g722",
00448    .exts = "g722",
00449    .format = AST_FORMAT_G722,
00450    .write = pcm_write,
00451    .seek = pcm_seek,
00452    .trunc = pcm_trunc,
00453    .tell = pcm_tell,
00454    .read = pcm_read,
00455    .buf_size = (BUF_SIZE * 2) + AST_FRIENDLY_OFFSET,
00456 };
00457 
00458 static const struct ast_format au_f = {
00459    .name = "au",
00460    .exts = "au",
00461    .format = AST_FORMAT_ULAW,
00462    .open = au_open,
00463    .rewrite = au_rewrite,
00464    .write = pcm_write,
00465    .seek = au_seek,
00466    .trunc = au_trunc,
00467    .tell = au_tell,
00468    .read = pcm_read,
00469    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,  /* this many shorts */
00470 };
00471 
00472 static int load_module(void)
00473 {
00474    int index;
00475 
00476    /* XXX better init ? */
00477    for (index = 0; index < (sizeof(ulaw_silence) / sizeof(ulaw_silence[0])); index++)
00478       ulaw_silence[index] = AST_LIN2MU(0);
00479    for (index = 0; index < (sizeof(alaw_silence) / sizeof(alaw_silence[0])); index++)
00480       alaw_silence[index] = AST_LIN2A(0);
00481 
00482    return ast_format_register(&pcm_f)
00483       || ast_format_register(&alaw_f)
00484       || ast_format_register(&au_f)
00485       || ast_format_register(&g722_f);
00486 }
00487 
00488 static int unload_module(void)
00489 {
00490    return ast_format_unregister(pcm_f.name)
00491       || ast_format_unregister(alaw_f.name)
00492       || ast_format_unregister(au_f.name)
00493       || ast_format_unregister(g722_f.name);
00494 }  
00495 
00496 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Raw/Sun uLaw/ALaw 8KHz (PCM,PCMA,AU), G.722 16Khz");

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