synnewdata.c

linux环境下用纯c写的RTP协议的通用开发库

/*-------------------------------------------------------------------------
 * synnewdata.c - synnewdata
 *-------------------------------------------------------------------------
 */

#include <syn.h>

/*------------------------------------------------------------------------
 * synnewdata - called on every new packet when buffering and on head
 * data (packets inserted at queue head). Determines if buffering is 
 * complete and signals any threads waiting on read for the stream.
 *------------------------------------------------------------------------
 */
int
synnewdata(struct synsession *pssn, ssrc_t ssrc)
{

	struct synstream	*psstm;
	mediatime_t             begin, end;
#ifdef RTPLIB_SYNCHRONIZE
	char		        cname[256];
#endif /* RTPLIB_SYNCHRONIZE */

	psstm = syngetstream(pssn, ssrc);
	if (psstm == NULL)
		return ERROR;

	/*
	 * Check that stream still exists at RTP layer.
	 * I.e., we did not miss a timed out event.
	 */
	if (rtpctl(pssn->ssn_session, RTP_CTL_STREAM_EXISTS, NULL, 0, ssrc) < 0) {
		synstreamoff(pssn, ssrc);
		synreleasestream(pssn, psstm);
		return ERROR;
	}

	if (psstm->sstm_buffering == TRUE) {

		/*
		 * Check the span. If it is greater than or 
		 * equal to psstm->sstm_jitterthresh,
		 * buffering is finished.
		 */
		if (synbufspan(pssn, psstm, &begin, &end) == ERROR) {
			synreleasestream(pssn, psstm);
			return ERROR;
		}
    
		if (end - begin >= psstm->sstm_jitthresh) {

			/* 
			 * Once buffering is complete, we no
			 * longer need event on each packet.
			 */
			eventqfilterssrc(&pssn->ssn_events, EVENT_RTP, psstm->sstm_ssrc, FALSE);

			/*
			 * Set relation between local clock and 
			 * this stream's media clock.
			 */ 
			psstm->sstm_clky = begin;
			clock_gettime(CLOCK_REALTIME, &psstm->sstm_clkx);

			/*
			 * Wake any threads waiting to read from this stream.
			 */
			if (pthread_mutex_lock(&psstm->sstm_readmutex) != 0) {
				synreleasestream(pssn, psstm);
				return ERROR;
			}
			psstm->sstm_buffering = FALSE;
			pthread_cond_broadcast(&psstm->sstm_readcond);
			pthread_mutex_unlock(&psstm->sstm_readmutex);

#ifdef RTPLIB_SYNCHRONIZE
			/*
			 * Attempt to synchronize when buffering done.
			 */
			rtpctl(pssn->ssn_session, RTP_CTL_STREAM_GETCNAME, cname, 256, psstm->sstm_ssrc);
			synsynchronize(pssn, cname);
#endif /* RTPLIB_SYNCHRONIZE */
		}
	}
	else {
		if (pthread_mutex_lock(&psstm->sstm_readmutex) != 0) {
			synreleasestream(pssn, psstm);
			return ERROR;
		}
		pthread_cond_signal(&psstm->sstm_readcond);
		pthread_mutex_unlock(&psstm->sstm_readmutex);
	}
	synreleasestream(pssn, psstm);
	return OK;
}