format_pcm.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Flat, binary, ulaw PCM file format.
 * \arg File name extension: alaw, al, alw, pcm, ulaw, ul, mu, ulw, g722, au
 *
 * \ingroup formats
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/mod_format.h"
#include "asterisk/module.h"
#include "asterisk/endian.h"
#include "asterisk/ulaw.h"
#include "asterisk/alaw.h"
#include "asterisk/format_cache.h"

#define BUF_SIZE 160    /* 160 bytes, and same number of samples */

static char ulaw_silence[BUF_SIZE];
static char alaw_silence[BUF_SIZE];

/* #define REALTIME_WRITE */  /* XXX does it work at all ? */

#ifdef REALTIME_WRITE
struct pcm_desc {
   unsigned long start_time;
};

/* Returns time in msec since system boot. */
static unsigned long get_time(void)
{
   struct tms buf;
   clock_t cur;

   cur = times( &buf );
   if( cur < 0 ) {
      ast_log( LOG_WARNING, "Cannot get current time\n" );
      return 0;
   }
   return cur * 1000 / sysconf( _SC_CLK_TCK );
}

static int pcma_open(struct ast_filestream *s)
{
   if (ast_format_cmp(s->fmt->format, ast_format_alaw) == AST_FORMAT_CMP_EQUAL)
      pd->starttime = get_time();
   return 0;
}

static int pcma_rewrite(struct ast_filestream *s, const char *comment)
{
   return pcma_open(s);
}
#endif

static struct ast_frame *pcm_read(struct ast_filestream *s, int *whennext)
{
   size_t res;

   /* Send a frame from the file to the appropriate channel */
   AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
   if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) < 1) {
      if (res) {
         ast_log(LOG_WARNING, "Short read of %s data (expected %d bytes, read %zu): %s\n",
               ast_format_get_name(s->fr.subclass.format), s->fr.datalen, res,
               strerror(errno));
      }
      return NULL;
   }
   s->fr.datalen = res;
   *whennext = s->fr.samples = res;
   return &s->fr;
}

static int pcm_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
   off_t cur, max, offset = 0;
   int ret = -1;  /* assume error */

   if ((cur = ftello(fs->f)) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to determine current position in pcm filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }

   if (fseeko(fs->f, 0, SEEK_END) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to seek to end of pcm filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }

   if ((max = ftello(fs->f)) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to determine max position in pcm filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }

   switch (whence) {
   case SEEK_SET:
      offset = sample_offset;
      break;
   case SEEK_END:
      offset = max - sample_offset;
      break;
   case SEEK_CUR:
   case SEEK_FORCECUR:
      offset = cur + sample_offset;
      break;
   default:
      ast_log(LOG_WARNING, "invalid whence %d, assuming SEEK_SET\n", whence);
      offset = sample_offset;
   }
   if (offset < 0) {
      ast_log(LOG_WARNING, "negative offset %ld, resetting to 0\n", (long) offset);
      offset = 0;
   }
   if (whence == SEEK_FORCECUR && offset > max) { /* extend the file */
      size_t left = offset - max;
      const char *src = (ast_format_cmp(fs->fmt->format, ast_format_alaw) == AST_FORMAT_CMP_EQUAL) ? alaw_silence : ulaw_silence;

      while (left) {
         size_t written = fwrite(src, 1, MIN(left, BUF_SIZE), fs->f);
         if (written < MIN(left, BUF_SIZE)) {
            break;   /* error */
         }
         left -= written;
      }
      ret = 0; /* successful */
   } else {
      if (offset > max) {
         ast_log(LOG_WARNING, "offset too large %ld, truncating to %ld\n", (long) offset, (long) max);
         offset = max;
      }
      ret = fseeko(fs->f, offset, SEEK_SET);
   }
   return ret;
}

static int pcm_trunc(struct ast_filestream *fs)
{
   int cur, fd;

   if ((fd = fileno(fs->f)) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for pcm filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }
   if ((cur = ftello(fs->f)) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to determine current position in pcm filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }
   /* Truncate file to current length */
   return ftruncate(fd, cur);
}

static off_t pcm_tell(struct ast_filestream *fs)
{
   return ftello(fs->f);
}

static int pcm_write(struct ast_filestream *fs, struct ast_frame *f)
{
   int res;

#ifdef REALTIME_WRITE
   if (ast_format_cmp(s->fmt->format, ast_format_alaw) == AST_FORMAT_CMP_EQUAL) {
      struct pcm_desc *pd = (struct pcm_desc *)fs->_private;
      struct stat stat_buf;
      unsigned long cur_time = get_time();
      unsigned long fpos = ( cur_time - pd->start_time ) * 8;  /* 8 bytes per msec */
      /* Check if we have written to this position yet. If we have, then increment pos by one frame
      *  for some degree of protection against receiving packets in the same clock tick.
      */

      fstat(fileno(fs->f), &stat_buf );
      if (stat_buf.st_size > fpos )
         fpos += f->datalen;  /* Incrementing with the size of this current frame */

      if (stat_buf.st_size < fpos) {
         /* fill the gap with 0x55 rather than 0. */
         char buf[1024];
         unsigned long cur, to_write;

         cur = stat_buf.st_size;
         if (fseek(fs->f, cur, SEEK_SET) < 0) {
            ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
            return -1;
         }
         memset(buf, 0x55, 512);
         while (cur < fpos) {
            to_write = fpos - cur;
            if (to_write > sizeof(buf))
               to_write = sizeof(buf);
            if (fwrite(buf, 1, to_write, fs->f) != to_write) {
               ast_log(LOG_ERROR, "Failed to write to file: %s\n", strerror(errno));
               return -1;
            }
            cur += to_write;
         }
      }

      if (fseek(s->f, fpos, SEEK_SET) < 0) {
         ast_log( LOG_WARNING, "Cannot seek in file: %s\n", strerror(errno) );
         return -1;
      }
   }
#endif   /* REALTIME_WRITE */

   if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
      ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
      return -1;
   }
   return 0;
}

/* SUN .au support routines */

#define MIN_AU_HEADER_SIZE 24
#define AU_HEADER(var)     uint32_t var[6]

#define AU_HDR_MAGIC_OFF   0
#define AU_HDR_HDR_SIZE_OFF   1
#define AU_HDR_DATA_SIZE_OFF  2
#define AU_HDR_ENCODING_OFF   3
#define AU_HDR_SAMPLE_RATE_OFF   4
#define AU_HDR_CHANNELS_OFF   5

#define AU_ENC_8BIT_ULAW   1

#define AU_MAGIC 0x2e736e64
#if __BYTE_ORDER == __BIG_ENDIAN
#define htoll(b) (b)
#define htols(b) (b)
#define ltohl(b) (b)
#define ltohs(b) (b)
#else
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define htoll(b)  \
          (((((b)      ) & 0xFF) << 24) | \
          ((((b) >>  8) & 0xFF) << 16) | \
         ((((b) >> 16) & 0xFF) <<  8) | \
         ((((b) >> 24) & 0xFF)      ))
#define htols(b) \
          (((((b)      ) & 0xFF) << 8) | \
         ((((b) >> 8) & 0xFF)      ))
#define ltohl(b) htoll(b)
#define ltohs(b) htols(b)
#else
#error "Endianess not defined"
#endif
#endif

struct au_desc {
   uint32_t hdr_size;
};

static int check_header(struct ast_filestream *fs)
{
   AU_HEADER(header);
   uint32_t magic;
   uint32_t hdr_size;
   uint32_t data_size;
   uint32_t encoding;
   uint32_t sample_rate;
   uint32_t channels;

   struct au_desc *desc = fs->_private;
   FILE *f = fs->f;

   if (fread(header, 1, MIN_AU_HEADER_SIZE, f) != MIN_AU_HEADER_SIZE) {
      ast_log(LOG_WARNING, "Read failed (header)\n");
      return -1;
   }
   magic = ltohl(header[AU_HDR_MAGIC_OFF]);
   if (magic != (uint32_t) AU_MAGIC) {
      ast_log(LOG_WARNING, "Bad magic: 0x%x\n", magic);
   }
   hdr_size = ltohl(header[AU_HDR_HDR_SIZE_OFF]);
   if (hdr_size < MIN_AU_HEADER_SIZE) {
      hdr_size = MIN_AU_HEADER_SIZE;
   }
/* data_size = ltohl(header[AU_HDR_DATA_SIZE_OFF]); */
   encoding = ltohl(header[AU_HDR_ENCODING_OFF]);
   if (encoding != AU_ENC_8BIT_ULAW) {
      ast_log(LOG_WARNING, "Unexpected format: %u. Only 8bit ULAW allowed (%d)\n", encoding, AU_ENC_8BIT_ULAW);
      return -1;
   }
   sample_rate = ltohl(header[AU_HDR_SAMPLE_RATE_OFF]);
   if (sample_rate != DEFAULT_SAMPLE_RATE) {
      ast_log(LOG_WARNING, "Sample rate can only be 8000 not %u\n", sample_rate);
      return -1;
   }
   channels = ltohl(header[AU_HDR_CHANNELS_OFF]);
   if (channels != 1) {
      ast_log(LOG_WARNING, "Not in mono: channels=%u\n", channels);
      return -1;
   }
   /* Skip to data */
   fseek(f, 0, SEEK_END);
   data_size = ftell(f) - hdr_size;
   if (fseek(f, hdr_size, SEEK_SET) == -1 ) {
      ast_log(LOG_WARNING, "Failed to skip to data: %u\n", hdr_size);
      return -1;
   }

   /* We'll need this later */
   desc->hdr_size = hdr_size;

   return data_size;
}

static int update_header(struct ast_filestream *fs)
{
   off_t cur, end;
   uint32_t datalen;
   int bytes;
   struct au_desc *desc = fs->_private;
   FILE *f = fs->f;

   cur = ftell(f);
   fseek(f, 0, SEEK_END);
   end = ftell(f);
   /* data starts 24 bytes in */
   bytes = end - desc->hdr_size;
   datalen = htoll(bytes);

   if (cur < 0) {
      ast_log(LOG_WARNING, "Unable to find our position\n");
      return -1;
   }
   if (fseek(f, AU_HDR_DATA_SIZE_OFF * sizeof(uint32_t), SEEK_SET)) {
      ast_log(LOG_WARNING, "Unable to set our position\n");
      return -1;
   }
   if (fwrite(&datalen, 1, sizeof(datalen), f) != sizeof(datalen)) {
      ast_log(LOG_WARNING, "Unable to set write file size\n");
      return -1;
   }
   if (fseek(f, cur, SEEK_SET)) {
      ast_log(LOG_WARNING, "Unable to return to position\n");
      return -1;
   }
   return 0;
}

static int write_header(struct ast_filestream *fs)
{
   struct au_desc *desc = fs->_private;
   FILE *f = fs->f;

   AU_HEADER(header);

   header[AU_HDR_MAGIC_OFF] = htoll((uint32_t) AU_MAGIC);
   header[AU_HDR_HDR_SIZE_OFF] = htoll(desc->hdr_size);
   header[AU_HDR_DATA_SIZE_OFF] = 0;
   header[AU_HDR_ENCODING_OFF] = htoll(AU_ENC_8BIT_ULAW);
   header[AU_HDR_SAMPLE_RATE_OFF] = htoll(DEFAULT_SAMPLE_RATE);
   header[AU_HDR_CHANNELS_OFF] = htoll(1);

   /* Write an au header, ignoring sizes which will be filled in later */
   fseek(f, 0, SEEK_SET);
   if (fwrite(header, 1, MIN_AU_HEADER_SIZE, f) != MIN_AU_HEADER_SIZE) {
      ast_log(LOG_WARNING, "Unable to write header\n");
      return -1;
   }
   return 0;
}

static int au_open(struct ast_filestream *s)
{
   if (check_header(s) < 0)
      return -1;
   return 0;
}

static int au_rewrite(struct ast_filestream *s, const char *comment)
{
   struct au_desc *desc = s->_private;

   desc->hdr_size = MIN_AU_HEADER_SIZE;

   if (write_header(s))
      return -1;
   return 0;
}

/* XXX check this, probably incorrect */
static int au_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
   off_t min, max, cur;
   long offset = 0;
   struct au_desc *desc = fs->_private;

   min = desc->hdr_size;

   if ((cur = ftello(fs->f)) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to determine current position in au filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }

   if (fseeko(fs->f, 0, SEEK_END) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to seek to end of au filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }

   if ((max = ftello(fs->f)) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to determine max position in au filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }

   if (whence == SEEK_SET)
      offset = sample_offset + min;
   else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
      offset = sample_offset + cur;
   else if (whence == SEEK_END)
      offset = max - sample_offset;

   if (whence != SEEK_FORCECUR) {
      offset = (offset > max) ? max : offset;
   }

   /* always protect the header space. */
   offset = (offset < min) ? min : offset;

   return fseeko(fs->f, offset, SEEK_SET);
}

static int au_trunc(struct ast_filestream *fs)
{
   int fd;
   off_t cur;

   if ((fd = fileno(fs->f)) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for au filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }
   if ((cur = ftello(fs->f)) < 0) {
      ast_log(AST_LOG_WARNING, "Unable to determine current position in au filestream %p: %s\n", fs, strerror(errno));
      return -1;
   }
   /* Truncate file to current length */
   if (ftruncate(fd, cur)) {
      return -1;
   }
   return update_header(fs);
}

static off_t au_tell(struct ast_filestream *fs)
{
   struct au_desc *desc = fs->_private;
   off_t offset = ftello(fs->f);
   return offset - desc->hdr_size;
}

static struct ast_frame *g722_read(struct ast_filestream *s, int *whennext)
{
   struct ast_frame *f = pcm_read(s, whennext);
   *whennext = s->fr.samples = (*whennext * 2);
   return f;
}

static int g722_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
   return pcm_seek(fs, sample_offset / 2, whence);
}

static off_t g722_tell(struct ast_filestream *fs)
{
   return pcm_tell(fs) * 2;
}

static struct ast_format_def alaw_f = {
   .name = "alaw",
   .exts = "alaw|al|alw",
   .write = pcm_write,
   .seek = pcm_seek,
   .trunc = pcm_trunc,
   .tell = pcm_tell,
   .read = pcm_read,
   .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
#ifdef REALTIME_WRITE
   .open = pcma_open,
   .rewrite = pcma_rewrite,
   .desc_size = sizeof(struct pcm_desc),
#endif
};

static struct ast_format_def pcm_f = {
   .name = "pcm",
   .exts = "pcm|ulaw|ul|mu|ulw",
   .mime_types = "audio/basic",
   .write = pcm_write,
   .seek = pcm_seek,
   .trunc = pcm_trunc,
   .tell = pcm_tell,
   .read = pcm_read,
   .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
};

static struct ast_format_def g722_f = {
   .name = "g722",
   .exts = "g722",
   .write = pcm_write,
   .seek = g722_seek,
   .trunc = pcm_trunc,
   .tell = g722_tell,
   .read = g722_read,
   .buf_size = (BUF_SIZE * 2) + AST_FRIENDLY_OFFSET,
};

static struct ast_format_def au_f = {
   .name = "au",
   .exts = "au",
   .open = au_open,
   .rewrite = au_rewrite,
   .write = pcm_write,
   .seek = au_seek,
   .trunc = au_trunc,
   .tell = au_tell,
   .read = pcm_read,
   .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,  /* this many shorts */
   .desc_size = sizeof(struct au_desc),
};

static int unload_module(void)
{
   return ast_format_def_unregister(pcm_f.name)
      || ast_format_def_unregister(alaw_f.name)
      || ast_format_def_unregister(au_f.name)
      || ast_format_def_unregister(g722_f.name);
}

static int load_module(void)
{
   int i;

   /* XXX better init ? */
   for (i = 0; i < ARRAY_LEN(ulaw_silence); i++)
      ulaw_silence[i] = AST_LIN2MU(0);
   for (i = 0; i < ARRAY_LEN(alaw_silence); i++)
      alaw_silence[i] = AST_LIN2A(0);

   pcm_f.format = ast_format_ulaw;
   alaw_f.format = ast_format_alaw;
   au_f.format = ast_format_ulaw;
   g722_f.format = ast_format_g722;
   if ( ast_format_def_register(&pcm_f)
      || ast_format_def_register(&alaw_f)
      || ast_format_def_register(&au_f)
      || ast_format_def_register(&g722_f) ) {
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }
   return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw/Sun uLaw/ALaw 8KHz (PCM,PCMA,AU), G.722 16Khz",
   .support_level = AST_MODULE_SUPPORT_CORE,
   .load = load_module,
   .unload = unload_module,
   .load_pri = AST_MODPRI_APP_DEPEND
);