rtp_server.c

ser作为一个高效、高度可配置的simple服务器

#include <sys/types.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "rtp_server.h"
#include "rtpp_util.h"
#include "rtp.h"

struct rtp_server *
rtp_server_new(const char *name, rtp_type_t codec, int loop)
{
    struct rtp_server *rp;
    int fd;
    char path[PATH_MAX + 1];

    sprintf(path, "%s.%d", name, codec);
    fd = open(path, O_RDONLY);
    if (fd == -1)
	return NULL;

    rp = malloc(sizeof(*rp));
    if (rp == NULL)
	return NULL;

    memset(rp, 0, sizeof(*rp));

    seedrandom();
    rp->btime = -1;
    rp->fd = fd;
    rp->loop = (loop > 0) ? loop - 1 : loop;

    rp->rtp = (rtp_hdr_t *)rp->buf;
    rp->rtp->version = 2;
    rp->rtp->p = 0;
    rp->rtp->x = 0;
    rp->rtp->cc = 0;
    rp->rtp->m = 0;
    rp->rtp->pt = codec;
    rp->rtp->ts = 0;
    rp->rtp->seq = 0;
    rp->rtp->ssrc = random();
    rp->pload = rp->buf + RTP_HDR_LEN(rp->rtp);

    return rp;
}

void
rtp_server_free(struct rtp_server *rp)
{

    close(rp->fd);
    free(rp);
}

int
rtp_server_get(struct rtp_server *rp)
{
    uint32_t ts;
    int rlen, rticks, bytes_per_frame, ticks_per_frame, number_of_frames;

    if (rp->btime == -1)
	rp->btime = getctime();

    ts = ntohl(rp->rtp->ts);

    if (rp->btime + ((double)ts / RTPS_SRATE) > getctime())
	return RTPS_LATER;

    switch (rp->rtp->pt) {
    case RTP_PCMU:
    case RTP_PCMA:
	bytes_per_frame = 8;
	ticks_per_frame = 1;
	break;

    case RTP_G729:
	/* 10 ms per 8 kbps G.729 frame */
	bytes_per_frame = 10;
	ticks_per_frame = 10;
	break;

    case RTP_G723:
	/* 30 ms per 6.3 kbps G.723 frame */
	bytes_per_frame = 24;
	ticks_per_frame = 30;
	break;

    default:
	return RTPS_ERROR;
    }

    number_of_frames = RTPS_TICKS_MIN / ticks_per_frame;
    if (RTPS_TICKS_MIN % ticks_per_frame != 0)
	number_of_frames++;

    rlen = bytes_per_frame * number_of_frames;
    rticks = ticks_per_frame * number_of_frames;

    if (read(rp->fd, rp->pload, rlen) != rlen) {
	if (rp->loop == 0 || lseek(rp->fd, 0, SEEK_SET) == -1 ||
	  read(rp->fd, rp->pload, rlen) != rlen)
	    return RTPS_EOF;
	if (rp->loop != -1)
	    rp->loop -= 1;
    }

    rp->rtp->ts = htonl(ts + (RTPS_SRATE * rticks / 1000));
    rp->rtp->seq = htons(ntohs(rp->rtp->seq) + 1);

    return (rp->pload - rp->buf) + rlen;
}