Wed Jan 27 20:02:11 2016

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: alaw, al, alw, pcm, ulaw, ul, mu, ulw, g722, au
00023  * 
00024  * \ingroup formats
00025  */
00026 
00027 /*** MODULEINFO
00028    <support_level>core</support_level>
00029  ***/
00030  
00031 #include "asterisk.h"
00032 
00033 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 413586 $")
00034 
00035 #include "asterisk/mod_format.h"
00036 #include "asterisk/module.h"
00037 #include "asterisk/endian.h"
00038 #include "asterisk/ulaw.h"
00039 #include "asterisk/alaw.h"
00040 
00041 #define BUF_SIZE 160    /* 160 bytes, and same number of samples */
00042 
00043 static char ulaw_silence[BUF_SIZE];
00044 static char alaw_silence[BUF_SIZE];
00045 
00046 /* #define REALTIME_WRITE */  /* XXX does it work at all ? */
00047 
00048 #ifdef REALTIME_WRITE
00049 struct pcm_desc {
00050    unsigned long start_time;
00051 };
00052 
00053 /* Returns time in msec since system boot. */
00054 static unsigned long get_time(void)
00055 {
00056    struct tms buf;
00057    clock_t cur;
00058 
00059    cur = times( &buf );
00060    if( cur < 0 ) {
00061       ast_log( LOG_WARNING, "Cannot get current time\n" );
00062       return 0;
00063    }
00064    return cur * 1000 / sysconf( _SC_CLK_TCK );
00065 }
00066 
00067 static int pcma_open(struct ast_filestream *s)
00068 {
00069    if (s->fmt->format == AST_FORMAT_ALAW)
00070       pd->starttime = get_time();
00071    return 0;
00072 }
00073 
00074 static int pcma_rewrite(struct ast_filestream *s, const char *comment)
00075 {
00076    return pcma_open(s);
00077 }
00078 #endif
00079 
00080 static struct ast_frame *pcm_read(struct ast_filestream *s, int *whennext)
00081 {
00082    int res;
00083    
00084    /* Send a frame from the file to the appropriate channel */
00085 
00086    s->fr.frametype = AST_FRAME_VOICE;
00087    s->fr.subclass.codec = s->fmt->format;
00088    s->fr.mallocd = 0;
00089    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00090    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) < 1) {
00091       if (res)
00092          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00093       return NULL;
00094    }
00095    s->fr.datalen = res;
00096    if (s->fmt->format == AST_FORMAT_G722)
00097       *whennext = s->fr.samples = res * 2;
00098    else
00099       *whennext = s->fr.samples = res;
00100    return &s->fr;
00101 }
00102 
00103 static int pcm_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00104 {
00105    off_t cur, max, offset = 0;
00106    int ret = -1;  /* assume error */
00107 
00108    if ((cur = ftello(fs->f)) < 0) {
00109       ast_log(AST_LOG_WARNING, "Unable to determine current position in pcm filestream %p: %s\n", fs, strerror(errno));
00110       return -1;
00111    }
00112 
00113    if (fseeko(fs->f, 0, SEEK_END) < 0) {
00114       ast_log(AST_LOG_WARNING, "Unable to seek to end of pcm filestream %p: %s\n", fs, strerror(errno));
00115       return -1;
00116    }
00117 
00118    if ((max = ftello(fs->f)) < 0) {
00119       ast_log(AST_LOG_WARNING, "Unable to determine max position in pcm filestream %p: %s\n", fs, strerror(errno));
00120       return -1;
00121    }
00122 
00123    switch (whence) {
00124    case SEEK_SET:
00125       offset = sample_offset;
00126       break;
00127    case SEEK_END:
00128       offset = max - sample_offset;
00129       break;
00130    case SEEK_CUR:
00131    case SEEK_FORCECUR:
00132       offset = cur + sample_offset;
00133       break;
00134    default:
00135       ast_log(LOG_WARNING, "invalid whence %d, assuming SEEK_SET\n", whence);
00136       offset = sample_offset;
00137    }
00138    if (offset < 0) {
00139       ast_log(LOG_WARNING, "negative offset %ld, resetting to 0\n", (long) offset);
00140       offset = 0;
00141    }
00142    if (whence == SEEK_FORCECUR && offset > max) { /* extend the file */
00143       size_t left = offset - max;
00144       const char *src = (fs->fmt->format == AST_FORMAT_ALAW) ? alaw_silence : ulaw_silence;
00145 
00146       while (left) {
00147          size_t written = fwrite(src, 1, (left > BUF_SIZE) ? BUF_SIZE : left, fs->f);
00148          if (written == -1)
00149             break;   /* error */
00150          left -= written;
00151       }
00152       ret = 0; /* successful */
00153    } else {
00154       if (offset > max) {
00155          ast_log(LOG_WARNING, "offset too large %ld, truncating to %ld\n", (long) offset, (long) max);
00156          offset = max;
00157       }
00158       ret = fseeko(fs->f, offset, SEEK_SET);
00159    }
00160    return ret;
00161 }
00162 
00163 static int pcm_trunc(struct ast_filestream *fs)
00164 {
00165    int cur, fd;
00166 
00167    if ((fd = fileno(fs->f)) < 0) {
00168       ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for pcm filestream %p: %s\n", fs, strerror(errno));
00169       return -1;
00170    }
00171    if ((cur = ftello(fs->f)) < 0) {
00172       ast_log(AST_LOG_WARNING, "Unable to determine current position in pcm filestream %p: %s\n", fs, strerror(errno));
00173       return -1;
00174    }
00175    /* Truncate file to current length */
00176    return ftruncate(fd, cur);
00177 }
00178 
00179 static off_t pcm_tell(struct ast_filestream *fs)
00180 {
00181    return ftello(fs->f);
00182 }
00183 
00184 static int pcm_write(struct ast_filestream *fs, struct ast_frame *f)
00185 {
00186    int res;
00187 
00188    if (f->frametype != AST_FRAME_VOICE) {
00189       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00190       return -1;
00191    }
00192    if (f->subclass.codec != fs->fmt->format) {
00193       ast_log(LOG_WARNING, "Asked to write incompatible format frame (%s)!\n", ast_getformatname(f->subclass.codec));
00194       return -1;
00195    }
00196 
00197 #ifdef REALTIME_WRITE
00198    if (s->fmt->format == AST_FORMAT_ALAW) {
00199       struct pcm_desc *pd = (struct pcm_desc *)fs->_private;
00200       struct stat stat_buf;
00201       unsigned long cur_time = get_time();
00202       unsigned long fpos = ( cur_time - pd->start_time ) * 8;  /* 8 bytes per msec */
00203       /* Check if we have written to this position yet. If we have, then increment pos by one frame
00204       *  for some degree of protection against receiving packets in the same clock tick.
00205       */
00206       
00207       fstat(fileno(fs->f), &stat_buf );
00208       if (stat_buf.st_size > fpos )
00209          fpos += f->datalen;  /* Incrementing with the size of this current frame */
00210 
00211       if (stat_buf.st_size < fpos) {
00212          /* fill the gap with 0x55 rather than 0. */
00213          char buf[1024];
00214          unsigned long cur, to_write;
00215 
00216          cur = stat_buf.st_size;
00217          if (fseek(fs->f, cur, SEEK_SET) < 0) {
00218             ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
00219             return -1;
00220          }
00221          memset(buf, 0x55, 512);
00222          while (cur < fpos) {
00223             to_write = fpos - cur;
00224             if (to_write > sizeof(buf))
00225                to_write = sizeof(buf);
00226             fwrite(buf, 1, to_write, fs->f);
00227             cur += to_write;
00228          }
00229       }
00230 
00231       if (fseek(s->f, fpos, SEEK_SET) < 0) {
00232          ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
00233          return -1;
00234       }
00235    }
00236 #endif   /* REALTIME_WRITE */
00237    
00238    if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
00239       ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00240       return -1;
00241    }
00242    return 0;
00243 }
00244 
00245 /* SUN .au support routines */
00246 
00247 #define AU_HEADER_SIZE     24
00248 #define AU_HEADER(var)     uint32_t var[6]
00249 
00250 #define AU_HDR_MAGIC_OFF   0
00251 #define AU_HDR_HDR_SIZE_OFF   1
00252 #define AU_HDR_DATA_SIZE_OFF  2
00253 #define AU_HDR_ENCODING_OFF   3
00254 #define AU_HDR_SAMPLE_RATE_OFF   4
00255 #define AU_HDR_CHANNELS_OFF   5
00256 
00257 #define AU_ENC_8BIT_ULAW   1
00258 
00259 #define AU_MAGIC 0x2e736e64
00260 #if __BYTE_ORDER == __BIG_ENDIAN
00261 #define htoll(b) (b)
00262 #define htols(b) (b)
00263 #define ltohl(b) (b)
00264 #define ltohs(b) (b)
00265 #else
00266 #if __BYTE_ORDER == __LITTLE_ENDIAN
00267 #define htoll(b)  \
00268           (((((b)      ) & 0xFF) << 24) | \
00269           ((((b) >>  8) & 0xFF) << 16) | \
00270          ((((b) >> 16) & 0xFF) <<  8) | \
00271          ((((b) >> 24) & 0xFF)      ))
00272 #define htols(b) \
00273           (((((b)      ) & 0xFF) << 8) | \
00274          ((((b) >> 8) & 0xFF)      ))
00275 #define ltohl(b) htoll(b)
00276 #define ltohs(b) htols(b)
00277 #else
00278 #error "Endianess not defined"
00279 #endif
00280 #endif
00281 
00282 static int check_header(FILE *f)
00283 {
00284    AU_HEADER(header);
00285    uint32_t magic;
00286    uint32_t hdr_size;
00287    uint32_t data_size;
00288    uint32_t encoding;
00289    uint32_t sample_rate;
00290    uint32_t channels;
00291 
00292    if (fread(header, 1, AU_HEADER_SIZE, f) != AU_HEADER_SIZE) {
00293       ast_log(LOG_WARNING, "Read failed (header)\n");
00294       return -1;
00295    }
00296    magic = ltohl(header[AU_HDR_MAGIC_OFF]);
00297    if (magic != (uint32_t) AU_MAGIC) {
00298       ast_log(LOG_WARNING, "Bad magic: 0x%x\n", magic);
00299    }
00300    hdr_size = ltohl(header[AU_HDR_HDR_SIZE_OFF]);
00301    if (hdr_size < AU_HEADER_SIZE) {
00302       hdr_size = AU_HEADER_SIZE;
00303    }
00304 /* data_size = ltohl(header[AU_HDR_DATA_SIZE_OFF]); */
00305    encoding = ltohl(header[AU_HDR_ENCODING_OFF]);
00306    if (encoding != AU_ENC_8BIT_ULAW) {
00307       ast_log(LOG_WARNING, "Unexpected format: %u. Only 8bit ULAW allowed (%d)\n", encoding, AU_ENC_8BIT_ULAW);
00308       return -1;
00309    }
00310    sample_rate = ltohl(header[AU_HDR_SAMPLE_RATE_OFF]);
00311    if (sample_rate != DEFAULT_SAMPLE_RATE) {
00312       ast_log(LOG_WARNING, "Sample rate can only be 8000 not %u\n", sample_rate);
00313       return -1;
00314    }
00315    channels = ltohl(header[AU_HDR_CHANNELS_OFF]);
00316    if (channels != 1) {
00317       ast_log(LOG_WARNING, "Not in mono: channels=%u\n", channels);
00318       return -1;
00319    }
00320    /* Skip to data */
00321    fseek(f, 0, SEEK_END);
00322    data_size = ftell(f) - hdr_size;
00323    if (fseek(f, hdr_size, SEEK_SET) == -1 ) {
00324       ast_log(LOG_WARNING, "Failed to skip to data: %u\n", hdr_size);
00325       return -1;
00326    }
00327    return data_size;
00328 }
00329 
00330 static int update_header(FILE *f)
00331 {
00332    off_t cur, end;
00333    uint32_t datalen;
00334    int bytes;
00335 
00336    cur = ftell(f);
00337    fseek(f, 0, SEEK_END);
00338    end = ftell(f);
00339    /* data starts 24 bytes in */
00340    bytes = end - AU_HEADER_SIZE;
00341    datalen = htoll(bytes);
00342 
00343    if (cur < 0) {
00344       ast_log(LOG_WARNING, "Unable to find our position\n");
00345       return -1;
00346    }
00347    if (fseek(f, AU_HDR_DATA_SIZE_OFF * sizeof(uint32_t), SEEK_SET)) {
00348       ast_log(LOG_WARNING, "Unable to set our position\n");
00349       return -1;
00350    }
00351    if (fwrite(&datalen, 1, sizeof(datalen), f) != sizeof(datalen)) {
00352       ast_log(LOG_WARNING, "Unable to set write file size\n");
00353       return -1;
00354    }
00355    if (fseek(f, cur, SEEK_SET)) {
00356       ast_log(LOG_WARNING, "Unable to return to position\n");
00357       return -1;
00358    }
00359    return 0;
00360 }
00361 
00362 static int write_header(FILE *f)
00363 {
00364    AU_HEADER(header);
00365 
00366    header[AU_HDR_MAGIC_OFF] = htoll((uint32_t) AU_MAGIC);
00367    header[AU_HDR_HDR_SIZE_OFF] = htoll(AU_HEADER_SIZE);
00368    header[AU_HDR_DATA_SIZE_OFF] = 0;
00369    header[AU_HDR_ENCODING_OFF] = htoll(AU_ENC_8BIT_ULAW);
00370    header[AU_HDR_SAMPLE_RATE_OFF] = htoll(DEFAULT_SAMPLE_RATE);
00371    header[AU_HDR_CHANNELS_OFF] = htoll(1);
00372 
00373    /* Write an au header, ignoring sizes which will be filled in later */
00374    fseek(f, 0, SEEK_SET);
00375    if (fwrite(header, 1, AU_HEADER_SIZE, f) != AU_HEADER_SIZE) {
00376       ast_log(LOG_WARNING, "Unable to write header\n");
00377       return -1;
00378    }
00379    return 0;
00380 }
00381 
00382 static int au_open(struct ast_filestream *s)
00383 {
00384    if (check_header(s->f) < 0)
00385       return -1;
00386    return 0;
00387 }
00388 
00389 static int au_rewrite(struct ast_filestream *s, const char *comment)
00390 {
00391    if (write_header(s->f))
00392       return -1;
00393    return 0;
00394 }
00395 
00396 /* XXX check this, probably incorrect */
00397 static int au_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00398 {
00399    off_t min = AU_HEADER_SIZE, max, cur;
00400    long offset = 0, bytes;
00401 
00402    if (fs->fmt->format == AST_FORMAT_G722)
00403       bytes = sample_offset / 2;
00404    else
00405       bytes = sample_offset;
00406 
00407    if ((cur = ftello(fs->f)) < 0) {
00408       ast_log(AST_LOG_WARNING, "Unable to determine current position in au filestream %p: %s\n", fs, strerror(errno));
00409       return -1;
00410    }
00411 
00412    if (fseeko(fs->f, 0, SEEK_END) < 0) {
00413       ast_log(AST_LOG_WARNING, "Unable to seek to end of au filestream %p: %s\n", fs, strerror(errno));
00414       return -1;
00415    }
00416 
00417    if ((max = ftello(fs->f)) < 0) {
00418       ast_log(AST_LOG_WARNING, "Unable to determine max position in au filestream %p: %s\n", fs, strerror(errno));
00419       return -1;
00420    }
00421 
00422    if (whence == SEEK_SET)
00423       offset = bytes + min;
00424    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00425       offset = bytes + cur;
00426    else if (whence == SEEK_END)
00427       offset = max - bytes;
00428 
00429    if (whence != SEEK_FORCECUR) {
00430       offset = (offset > max) ? max : offset;
00431    }
00432 
00433    /* always protect the header space. */
00434    offset = (offset < min) ? min : offset;
00435 
00436    return fseeko(fs->f, offset, SEEK_SET);
00437 }
00438 
00439 static int au_trunc(struct ast_filestream *fs)
00440 {
00441    int fd;
00442    off_t cur;
00443 
00444    if ((fd = fileno(fs->f)) < 0) {
00445       ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for au filestream %p: %s\n", fs, strerror(errno));
00446       return -1;
00447    }
00448    if ((cur = ftello(fs->f)) < 0) {
00449       ast_log(AST_LOG_WARNING, "Unable to determine current position in au filestream %p: %s\n", fs, strerror(errno));
00450       return -1;
00451    }
00452    /* Truncate file to current length */
00453    if (ftruncate(fd, cur)) {
00454       return -1;
00455    }
00456    return update_header(fs->f);
00457 }
00458 
00459 static off_t au_tell(struct ast_filestream *fs)
00460 {
00461    off_t offset = ftello(fs->f);
00462    return offset - AU_HEADER_SIZE;
00463 }
00464 
00465 static const struct ast_format alaw_f = {
00466    .name = "alaw",
00467    .exts = "alaw|al|alw",
00468    .format = AST_FORMAT_ALAW,
00469    .write = pcm_write,
00470    .seek = pcm_seek,
00471    .trunc = pcm_trunc,
00472    .tell = pcm_tell,
00473    .read = pcm_read,
00474    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00475 #ifdef REALTIME_WRITE
00476    .open = pcma_open,
00477    .rewrite = pcma_rewrite,
00478    .desc_size = sizeof(struct pcm_desc),
00479 #endif
00480 };
00481 
00482 static const struct ast_format pcm_f = {
00483    .name = "pcm",
00484    .exts = "pcm|ulaw|ul|mu|ulw",
00485    .format = AST_FORMAT_ULAW,
00486    .write = pcm_write,
00487    .seek = pcm_seek,
00488    .trunc = pcm_trunc,
00489    .tell = pcm_tell,
00490    .read = pcm_read,
00491    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00492 };
00493 
00494 static const struct ast_format g722_f = {
00495    .name = "g722",
00496    .exts = "g722",
00497    .format = AST_FORMAT_G722,
00498    .write = pcm_write,
00499    .seek = pcm_seek,
00500    .trunc = pcm_trunc,
00501    .tell = pcm_tell,
00502    .read = pcm_read,
00503    .buf_size = (BUF_SIZE * 2) + AST_FRIENDLY_OFFSET,
00504 };
00505 
00506 static const struct ast_format au_f = {
00507    .name = "au",
00508    .exts = "au",
00509    .format = AST_FORMAT_ULAW,
00510    .open = au_open,
00511    .rewrite = au_rewrite,
00512    .write = pcm_write,
00513    .seek = au_seek,
00514    .trunc = au_trunc,
00515    .tell = au_tell,
00516    .read = pcm_read,
00517    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,  /* this many shorts */
00518 };
00519 
00520 static int load_module(void)
00521 {
00522    int i;
00523 
00524    /* XXX better init ? */
00525    for (i = 0; i < ARRAY_LEN(ulaw_silence); i++)
00526       ulaw_silence[i] = AST_LIN2MU(0);
00527    for (i = 0; i < ARRAY_LEN(alaw_silence); i++)
00528       alaw_silence[i] = AST_LIN2A(0);
00529 
00530    if ( ast_format_register(&pcm_f)
00531       || ast_format_register(&alaw_f)
00532       || ast_format_register(&au_f)
00533       || ast_format_register(&g722_f) )
00534       return AST_MODULE_LOAD_FAILURE;
00535    return AST_MODULE_LOAD_SUCCESS;
00536 }
00537 
00538 static int unload_module(void)
00539 {
00540    return ast_format_unregister(pcm_f.name)
00541       || ast_format_unregister(alaw_f.name)
00542       || ast_format_unregister(au_f.name)
00543       || ast_format_unregister(g722_f.name);
00544 }
00545 
00546 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw/Sun uLaw/ALaw 8KHz (PCM,PCMA,AU), G.722 16Khz",
00547    .load = load_module,
00548    .unload = unload_module,
00549    .load_pri = AST_MODPRI_APP_DEPEND
00550 );

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