format_pcm.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * 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
);