myvtm/libtoolkit/rtp.c

#include "precompile.h"
#include "rtp.h"

#include <time.h>
#include "modCheck.h"

#ifndef  H264_VIDEO_PT
#define H264_VIDEO_PT     97 // H264
#endif 

#define DEFAULT_RTP_STATE_TRANSMIT_INTERVAL	1500 /* 1.5 seconds */

struct rtp_state {
	/* for rtp sending */
	unsigned int ts; /* host byte order */
	unsigned int ssrc; /* network byte order */
	unsigned int p; /* padding bit */
	unsigned short seq; /* host byte order */
	unsigned int x; /* extension bit */

	/* for sdes */
	char *sdes_str[RTCP_SDES_COUNT];

	/* for statistics */
	rtcp_statistics s;

	/* for rtcp sending */
	DWORD transmit_interval;
	DWORD last_transmit_tick;

	/*for rtcp tmmbr */
	RtcpTmmbrInfo tmmbr_info;
};

#ifndef JAN_1970
#define     JAN_1970     0x83aa7e80     /* 2208988800 1970 - 1900 in seconds */
#endif

#define SECS_TO_FT_MULT 10000000



#define rtcp_fb_tmmbr_fci_get_ssrc(tmmbr) ntohl((tmmbr)->ssrc)
#define rtcp_fb_tmmbr_fci_get_mxtbr_exp(tmmbr) \
	((unsigned char)((ntohl((tmmbr)->value) >> 26) & 0x0000003F))
#define rtcp_fb_tmmbr_fci_set_mxtbr_exp(tmmbr, mxtbr_exp) \
	((tmmbr)->value) = htonl((ntohl((tmmbr)->value) & 0x03FFFFFF) | (((mxtbr_exp) & 0x0000003F) << 26))
#define rtcp_fb_tmmbr_fci_get_mxtbr_mantissa(tmmbr) \
	((unsigned int)((ntohl((tmmbr)->value) >> 9) & 0x0001FFFF))
#define rtcp_fb_tmmbr_fci_set_mxtbr_mantissa(tmmbr, mxtbr_mantissa) \
	((tmmbr)->value) = htonl((ntohl((tmmbr)->value) & 0xFC0001FF) | (((mxtbr_mantissa) & 0x0001FFFF) << 9))
#define rtcp_fb_tmmbr_fci_get_measured_overhead(tmmbr) \
	((unsigned short)(ntohl((tmmbr)->value) & 0x000001FF))
#define rtcp_fb_tmmbr_fci_set_measured_overhead(tmmbr, measured_overhead) \
	((tmmbr)->value) = htonl((ntohl((tmmbr)->value) & 0xFFFFFE00) | ((measured_overhead) & 0x000001FF))


#define MIN_RTCP_PSFB_PACKET_SIZE (sizeof(rtcp_common_t) + sizeof(rtcp_fb_header_t))
#define MIN_RTCP_RTPFB_PACKET_SIZE (sizeof(rtcp_common_t) + sizeof(rtcp_fb_header_t))


TOOLKIT_API int rtp_state_fill_rtcp_sender_info(rtp_state *rs, rtcp_sender_info_t *info);
TOOLKIT_API int rtp_state_fill_rtcp_reception_report(rtp_state *rs, rtcp_rr_t *report);
TOOLKIT_API int rtp_state_fill_rtcp_sdes_item(rtp_state *rs, rtcp_sdes_type_t type, rtcp_sdes_item_t *item, int *fill_n);
TOOLKIT_API int rtp_state_fill_rtcp_sdes_item_raw(rtp_state *rs, rtcp_sdes_type_t type, const char *str, rtcp_sdes_item_t *item, int *fill_n);
TOOLKIT_API int rtp_state_fill_rtcp_bye(rtp_state *rs, rtcp_bye_t* bye);
TOOLKIT_API int rtp_state_rtcp_make_bye(rtp_state *rs, char *buf, size_t buflen);
TOOLKIT_API int rtp_state_rtcp_make_h261_nack(rtp_state *rs, char *buf, size_t buflen);
TOOLKIT_API int rtp_state_set_sdes_str(rtp_state *rs, rtcp_sdes_type_t type, const char *str);
TOOLKIT_API void rtp_state_update_send_rtcp_ticks(rtp_state *state);

// Find 1st Jan 1970 as a FILETIME 
static void get_base_time(void)
{
	SYSTEMTIME st;
	FILETIME ft;

	memset(&st,0,sizeof(st));
	st.wYear=1970;
	st.wMonth=1;
	st.wDay=1;
	SystemTimeToFileTime(&st, &ft);

	/*for linux compatibility*/
	toolkit_getResource()->base_time.u.LowPart = ft.dwLowDateTime;
	toolkit_getResource()->base_time.u.HighPart = ft.dwHighDateTime;
	toolkit_getResource()->base_time.QuadPart /= SECS_TO_FT_MULT;
}

static void conflict_gettimeofday(struct timeval *tv)
{
#ifdef _WIN32
	SYSTEMTIME st;
	FILETIME ft;
	LARGE_INTEGER li;

	GetSystemTime(&st);
	SystemTimeToFileTime(&st, &ft);

	if (toolkit_getResource()->base_time.QuadPart == 0)
		get_base_time();

	li.u.LowPart = ft.dwLowDateTime;
	li.u.HighPart = ft.dwHighDateTime;
	li.QuadPart /= SECS_TO_FT_MULT;
	li.QuadPart -= toolkit_getResource()->base_time.QuadPart;

	tv->tv_sec = li.u.LowPart;
	tv->tv_usec = st.wMilliseconds * 1000;
#else
	gettimeofday(tv, NULL);
#endif
}

static char *copymsg(char *msg, int len)
{
	char *newm;
	newm=malloc(len);
	memcpy(newm,msg,len);
	return newm;
}

static void freemsg(char *msg)
{
	if (msg != NULL) {
		free(msg);
	}
}

static size_t rtcp_get_size(const char *msg){
	rtcp_common_t *ch = (rtcp_common_t *)msg;
	if (ch==NULL) return 0;
	return (1+ntohs(ch->length))*4;
}

static int rtcp_is_rtpfb(const char *msg) {
	rtcp_common_t *ch = (rtcp_common_t *)msg;
	if ((ch != NULL) && (ch->pt == RTCP_RTPFB)) {
		return TRUE;
	}
	return FALSE;
}

static rtcp_rtpfb_type_t rtcp_rtpfb_get_type(const char *msg) {
	rtcp_common_t *ch = (rtcp_common_t *)msg;
	return (rtcp_rtpfb_type_t)ch->count;
}

static unsigned int rtcp_rtpfb_get_packet_sender_ssrc(const char *msg) {
	rtcp_fb_header_t *fbh = (rtcp_fb_header_t *)(msg + sizeof(rtcp_common_t));
	return ntohl(fbh->packet_sender_ssrc);
}

static unsigned int rtcp_rtpfb_get_media_source_ssrc(const char *msg) {
	rtcp_fb_header_t *fbh = (rtcp_fb_header_t *)(msg + sizeof(rtcp_common_t));
	return ntohl(fbh->media_source_ssrc);
}

static rtcp_fb_tmmbr_fci_t * rtcp_rtpfb_tmmbr_get_fci(const char *msg) {
	size_t size = sizeof(rtcp_common_t) + sizeof(rtcp_fb_header_t) + sizeof(rtcp_fb_tmmbr_fci_t);
	size_t rtcp_size = rtcp_get_size(msg);
	if (size > rtcp_size) {
		return NULL;
	}
	return (rtcp_fb_tmmbr_fci_t *)(msg + size - sizeof(rtcp_fb_tmmbr_fci_t));
}

static u__int64_t rtcp_rtpfb_tmmbr_get_max_bitrate(const char *msg) {
	rtcp_fb_tmmbr_fci_t *fci = rtcp_rtpfb_tmmbr_get_fci(msg);
	return rtcp_fb_tmmbr_fci_get_mxtbr_mantissa(fci) * (1 << rtcp_fb_tmmbr_fci_get_mxtbr_exp(fci));
}


const rtcp_rr_t * rtcp_SR_get_report_block(const char *msg){
	rtcp_sr_t *sr=(rtcp_sr_t*)msg;
	rtcp_rr_t *rb=&sr->rb[0];
	size_t size=rtcp_get_size(msg);
	if ( ( (char *)rb)+sizeof(rtcp_rr_t) <= msg + size ) {
		return rb;
	}
	return NULL;
}


const rtcp_rr_t * rtcp_RR_get_report_block(const char *msg){
	int n = 0;
	size_t size;
	unsigned int *sender_ssrc;
	rtcp_rr_t *rb;
	//rtcp_common
	const rtcp_common_t *common = (rtcp_common_t *)msg;
	n += sizeof(rtcp_common_t);
	//sender_ssrc
	sender_ssrc = (unsigned int *)(msg + n);
	rb = (rtcp_rr_t *)(msg + n + sizeof(*sender_ssrc));
	size=rtcp_get_size(msg);
	if ( ( (char *)rb)+sizeof(rtcp_rr_t) <= (msg + size ) ){
		return rb;
	}
	return NULL;
}

TOOLKIT_API int rtp_state_fill_rtp(rtp_state *rs, void *hdr, unsigned int pt, unsigned int mark, unsigned int delta_ts)
{
	rtp_hdr *header;

	assert(rs && hdr);

	header = (rtp_hdr*)hdr;
	header->csrc = 0;
	header->x = rs->x;
	header->p = rs->p;
	header->v = 2;
	header->pt = pt&0x7f;
	header->m = !!mark;
	header->seq = htons(rs->seq);
	rs->seq++;
	rs->ts += delta_ts;
	
	if (H264_VIDEO_PT == pt) {
		header->ts = htonl(delta_ts);
	}
	else {
		header->ts = htonl(rs->ts);
	}

	header->ssrc = rs->ssrc;
	return 0;
}

TOOLKIT_API int rtp_state_advance_timestamp(rtp_state *rs, unsigned int delta_ts)
{
	assert(rs);
	rs->ts += delta_ts;
	return 0;
}

TOOLKIT_API int rtp_state_set_rtcp_sdes_string(rtp_state *rs, 
								   rtcp_sdes_type_t type, 
								   const char *str)
{
	if (!rs)
		return -1;
	if (type <= 0 || type > RTCP_SDES_PRIV)
		return -1;
	if (rs->sdes_str[type]) {
		free(rs->sdes_str[type]);
	}
	rs->sdes_str[type] = _strdup(str);
	return rs->sdes_str[type] ? 0 : -1;
}

static u__int64_t rtp_timeval_to_ntp(const struct timeval *tv){
   u__int64_t msw;
   u__int64_t lsw;
   msw=tv->tv_sec + 0x83AA7E80; /* 0x83AA7E80 is the number of seconds from 1900 to 1970 */
   lsw=(unsigned int)((double)tv->tv_usec*(double)(((u__int64_t)1)<<32)*1.0e-6);
   return msw<<32 | lsw;
}

TOOLKIT_API int rtp_state_fill_rtcp_sender_info(rtp_state *rs, rtcp_sender_info_t *info)
{
	struct timeval tv;
	u__int64_t ntp;

	if (!rs)
		return -1;
	info->ssrc = rs->ssrc; /* sender's own ssrc */
	conflict_gettimeofday(&tv);
	ntp=rtp_timeval_to_ntp(&tv);
	info->ntp_sec = htonl(ntp >>32);//(unsigned int)htonl(tv.tv_sec + JAN_1970);
	info->ntp_frac = htonl(ntp & 0xFFFFFFFF);//(unsigned int)htonl((unsigned long)(tv.tv_usec*4294.967296));
	info->rtp_ts = (unsigned int)htonl(rs->ts);
	info->psent = (unsigned int)htonl((unsigned long)rs->s.total_tx_packets);
	info->osent = (unsigned int)htonl((unsigned long)rs->s.total_tx_bytes);
	return 0;
}

TOOLKIT_API int rtp_state_fill_rtcp_reception_report(rtp_state *rs, rtcp_rr_t *report)
{
	int packet_loss_since_last_sr;
	unsigned char loss_fraction;
	unsigned int ext_seq;
	unsigned int expected;
	unsigned int delay_since_lsr = 0;

	if (!rs || !report)
		return -1;
	if (rs->s.last_seq == rs->s.first_seq && rs->s.seq_circles == 0) /* have not recv any peer's data */
		return -1;

	ext_seq = ((unsigned int)rs->s.seq_circles << 16 | (unsigned int)rs->s.last_seq);
	expected = ext_seq - rs->s.rx_seq_at_last_sr;
	packet_loss_since_last_sr = expected - rs->s.rx_packets_since_last_sr;
	if (packet_loss_since_last_sr < 0)
		packet_loss_since_last_sr = 0;
	rs->s.rx_seq_at_last_sr = ext_seq; /* update */
	rs->s.rx_packets_since_last_sr = 0;//RESET
	rs->s.total_packet_lost += (unsigned int)packet_loss_since_last_sr;
	if (expected == 0)
		expected = 1;
	if (rs->s.lsr_tm.tv_sec != 0) {
		struct timeval now;
		double delay;
		conflict_gettimeofday(&now);
		delay= (now.tv_sec-rs->s.lsr_tm.tv_sec)+ ((now.tv_usec-rs->s.lsr_tm.tv_usec)*1e-6);
		delay= (delay*65536);
		delay_since_lsr=(unsigned int) delay;
	}
	loss_fraction = (unsigned char)(256 * packet_loss_since_last_sr / expected);
	report->ssrc = rs->s.peer_ssrc;
	report->fl_cnpl = htonl((loss_fraction << 24) | (rs->s.total_packet_lost&0xffffff));
	report->last_seq = htonl(ext_seq);
	report->jitter = htonl(rs->s.inter_jitter);
	report->lsr = htonl(rs->s.lsr);
	report->dlsr = htonl(delay_since_lsr);
	
	return 0;
}

TOOLKIT_API int rtp_state_fill_rtcp_sdes_item_raw(rtp_state *rs, rtcp_sdes_type_t type, const char *str, rtcp_sdes_item_t *item, int *fill_n)
{
	if (!rs || !item || !fill_n)
		return -1;
	*fill_n = 0;
	if (type == RTCP_SDES_END) {
		char *t = (char*)item;
		do {
			*t++ = 0;
			*fill_n += 1;
		} while (((unsigned int)t&3) != 0); /* force 32-bit alignment */
	} else {
		int n = str ? (int)strlen(str) : 0;
		if (n) {
			n = min(n, 255);
			memcpy(&item->data[0], str, n);
		}
		item->type = type;
		item->length = (unsigned char)n;
		*fill_n = 2 + n;
	}
	return 0;
}

TOOLKIT_API int rtp_state_fill_rtcp_sdes_item(rtp_state *rs, rtcp_sdes_type_t type, rtcp_sdes_item_t *item, int *fill_n)
{
	if (!rs || !item || !fill_n)
		return -1;
	*fill_n = 0;
	if (type == RTCP_SDES_END) {
		char *t = (char*)item;
		do {
			*t++ = 0;
			*fill_n += 1;
		} while (((unsigned int)t&3) != 0); /* force 32-bit alignment */
	} else if (rs->sdes_str[type] == NULL) {
		return -1; /* null */
	} else {
		int n = (int)strlen(rs->sdes_str[type]);
		if (n) {
			memcpy(&item->data[0], rs->sdes_str[type], n);
		}
		item->type = type;
		item->length = (unsigned char)n;
		*fill_n = 2 + n;
	}
	return 0;
}

TOOLKIT_API int rtp_state_fill_rtcp_bye(rtp_state *rs, rtcp_bye_t* bye)
{
	if (!rs || !bye)
		return -1;
	bye->ssrc[0] = rs->ssrc;
	bye->common.pt = RTCP_BYE;
	bye->common.count = 1;
	bye->common.p = 0;
	bye->common.version = 2;
	bye->common.length = htons(1);
	return 0;
}

TOOLKIT_API int rtp_state_rtcp_make_sr(rtp_state *rs, char *buf, size_t buflen)
{
	rtcp_common_t *common;
	rtcp_sdes_t *sdes;
	int n, t, m;
	int reception_report_result;

	if (!buf)
		return -1;
	
	/* sr block */
	n = 0;
	common = (rtcp_common_t*)&buf[n];
	n += sizeof(rtcp_common_t);
	rtp_state_fill_rtcp_sender_info(rs, (rtcp_sender_info_t *)&buf[n]);
	n += sizeof(rtcp_sender_info_t);
	reception_report_result = rtp_state_fill_rtcp_reception_report(rs, (rtcp_rr_t *)&buf[n]);
	if (reception_report_result < 0){
	    //have not recv any peer's data, not fill_reception_report.
	} else {
		n += sizeof(rtcp_rr_t);
	}
	common->p = 0;
	common->version = 2;
	common->pt = RTCP_SR;
	common->count = 1;
	common->length = htons(n / 4 - 1);

	/* sdes block */
	m = n;
	common = (rtcp_common_t*)&buf[m];
	m += sizeof(rtcp_common_t);
	sdes = (rtcp_sdes_t *)&buf[m];
	sdes->ssrc = rs->ssrc;
	m += sizeof(sdes->ssrc);
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_CNAME, (rtcp_sdes_item_t*)&buf[m], &t);
	m += t;
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_END, (rtcp_sdes_item_t*)&buf[m], &t);
	m += t;
	common->p = 0;
	common->version = 2;
	common->pt = RTCP_SDES;
	common->count = 1;
	common->length = htons((m - n) / 4 - 1);

	return m;
}

TOOLKIT_API int rtp_state_rtcp_make_rr(rtp_state *rs, char *buf, size_t buflen)
{
	rtcp_common_t *common;
	rtcp_sdes_t *sdes;
	int n, t, m;
	unsigned int *sender_ssrc;
	int reception_report_result;

	if (!buf)
		return -1;

	/* sr block */
	n = 0;
	common = (rtcp_common_t*)&buf[n];
	n += sizeof(rtcp_common_t);
	sender_ssrc = (unsigned int *)&buf[n];
	*sender_ssrc = rs->ssrc; /* sender's own ssrc */
	n += sizeof(*sender_ssrc);
	reception_report_result = rtp_state_fill_rtcp_reception_report(rs, (rtcp_rr_t *)&buf[n]);
	if (reception_report_result < 0){
	    return reception_report_result;
	}
	n += sizeof(rtcp_rr_t);
	common->p = 0;
	common->version = 2;
	common->pt = RTCP_RR;
	common->count = 1;
	common->length = htons(n / 4 - 1);

	/* sdes block */
	m = n;
	common = (rtcp_common_t*)&buf[m];
	m += sizeof(rtcp_common_t);
	sdes = (rtcp_sdes_t *)&buf[m];
	sdes->ssrc = rs->ssrc;
	m += sizeof(sdes->ssrc);
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_CNAME, (rtcp_sdes_item_t*)&buf[m], &t);
	m += t;
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_END, (rtcp_sdes_item_t*)&buf[m], &t);
	m += t;
	common->p = 0;
	common->version = 2;
	common->pt = RTCP_SDES;
	common->count = 1;
	common->length = htons((m - n) / 4 - 1);

	return m;
}

TOOLKIT_API int rtp_state_rtcp_make_bye(rtp_state *rs, char *buf, size_t buflen)
{
	rtcp_bye_t* bye;
	rtcp_common_t *common;
	int n, t, m;

	if (!buf)
		return -1;

	/* bye block, already contains rtcp_common_t */
	n = 0;
	bye = (rtcp_bye_t*)&buf[n];
	n += sizeof(rtcp_bye_t);
	bye->common.p = 0;
	bye->common.version = 2;
	bye->common.pt = RTCP_BYE;
	bye->common.count = 1;
	bye->ssrc[0] = rs->ssrc;
	bye->common.length = htons(n / 4 - 1);

	/* sdes block */
	m = n;
	common = (rtcp_common_t*)&buf[m];
	m += sizeof(rtcp_common_t);
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_CNAME, (rtcp_sdes_item_t*)&buf[m], &t);
	m += t;
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_END, (rtcp_sdes_item_t*)&buf[m], &t);
	m += t;
	common->p = 1;
	common->version = 2;
	common->pt = RTCP_SDES;
	common->count = 1;
	common->length = htons((m - n) / 4 - 1);

	return m;
}

TOOLKIT_API int rtp_state_rtcp_make_h261_fir(rtp_state *rs, char *buf, size_t buflen)
{
	rtcp_fir_t *fir;
	rtcp_common_t *common;
	rtcp_sdes_t *sdes;
	int n, t, m;
	int reception_report_result;

	/* sr block */
	n = 0;
	common = (rtcp_common_t*)&buf[n];
	n += sizeof(rtcp_common_t);
	rtp_state_fill_rtcp_sender_info(rs, (rtcp_sender_info_t *)&buf[n]);
	n += sizeof(rtcp_sender_info_t);
	reception_report_result = rtp_state_fill_rtcp_reception_report(rs, (rtcp_rr_t *)&buf[n]);
	if (reception_report_result < 0){
	    //have not recv any peer's data, not fill_reception_report.
	} else {
		n += sizeof(rtcp_rr_t);
	}
	common->p = 0;
	common->version = 2;
	common->pt = RTCP_SR;
	common->count = 1;
	common->length = htons(n / 4 - 1);

	m = n;
	common = (rtcp_common_t*)&buf[n];
	n += sizeof(rtcp_common_t);
	sdes = (rtcp_sdes_t *)&buf[n];
	sdes->ssrc = rs->ssrc;
	n += sizeof(sdes->ssrc);
	//rtp_state_fill_rtcp_sdes_item_raw(rs, RTCP_SDES_CNAME, "fast_media_video_2b227aa1@huawei.com", (rtcp_sdes_item_t*)&buf[n], &t);
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_CNAME, (rtcp_sdes_item_t*)&buf[n], &t);
	n += t;
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_END, (rtcp_sdes_item_t*)&buf[n], &t);
	n += t;
	common->p = 0;
	common->version = 2;
	common->pt = RTCP_SDES;
	common->count = 1;
	common->length = htons((n-m) / 4 - 1);

	m = n;

	fir = (rtcp_fir_t *)&buf[n];
	n += sizeof(rtcp_fir_t);
	fir->common.p = 0;
	fir->common.pt = RTCP_FIR;
	fir->common.version = 2;
	fir->common.count = 1;
	fir->ssrc = rs->ssrc;
	fir->common.length = htons((n-m)/4 - 1);

	return n;
}

TOOLKIT_API int rtp_state_rtcp_make_h261_nack(rtp_state *rs, char *buf, size_t buflen)
{
	rtcp_common_t *common;
	int n, t, m;

	n = 0;
	common = (rtcp_common_t*)&buf[0];
	n += sizeof(rtcp_common_t);
	common->count = 0;
	common->version = 2;
	common->p = 0;
	common->pt = RTCP_NACK;
	common->length = htons(n / 4 - 1);

	/* sdes block */
	m = n;
	common = (rtcp_common_t*)&buf[m];
	m += sizeof(rtcp_common_t);
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_CNAME, (rtcp_sdes_item_t*)&buf[m], &t);
	m += t;
	rtp_state_fill_rtcp_sdes_item(rs, RTCP_SDES_END, (rtcp_sdes_item_t*)&buf[m], &t);
	m += t;
	common->p = 1;
	common->version = 2;
	common->pt = RTCP_SDES;
	common->count = 1;
	common->length = htons((m - n) / 4 - 1);

	return m;
}


TOOLKIT_API int rtp_state_rtcp_make_rtcp_fb_tmmbr(rtp_state *rs, char *buf, size_t buflen, u__int64_t mxtbr, unsigned short measured_overhead) {
	rtcp_common_t *ch;
	rtcp_fb_header_t *fbh;
	rtcp_fb_tmmbr_fci_t *fci;
	unsigned char mxtbr_exp = 0;
	unsigned int mxtbr_mantissa = 0;
	int length = 0;

	/* Compute mxtbr exp and mantissa */
	while (mxtbr >= (1 << 17)) {
		mxtbr >>= 1;
		mxtbr_exp++;
	}
	mxtbr_mantissa = mxtbr & 0x0001FFFF;

	/* Fill TMMBR */
	ch = (rtcp_common_t *)&buf[length];
	length += sizeof(rtcp_common_t);
	fbh = (rtcp_fb_header_t *)&buf[length];
	length += sizeof(rtcp_fb_header_t);
	fci = (rtcp_fb_tmmbr_fci_t *)&buf[length];
	length += sizeof(rtcp_fb_tmmbr_fci_t);
	fbh->packet_sender_ssrc = rs->ssrc;
	fbh->media_source_ssrc = htonl(0);
	fci->ssrc = rs->s.peer_ssrc;
	rtcp_fb_tmmbr_fci_set_mxtbr_exp(fci, mxtbr_exp);
	rtcp_fb_tmmbr_fci_set_mxtbr_mantissa(fci, mxtbr_mantissa);
	rtcp_fb_tmmbr_fci_set_measured_overhead(fci, measured_overhead);

	/* Fill common header */
	ch->p = 0;
	ch->version = 2;
	ch->pt = RTCP_RTPFB;
    ch->count = RTCP_RTPFB_TMMBR;
	ch->length = htons(length / 4 - 1);

	/* Store packet to be able to retransmit. */
	if (rs->tmmbr_info.sent) freemsg(rs->tmmbr_info.sent);
	rs->tmmbr_info.sent = copymsg(buf, length);

	return length;
}


TOOLKIT_API int rtp_state_rtcp_make_rtcp_fb_tmmbn(rtp_state *rs, char *buf, size_t buflen, unsigned int ssrc) {
	rtcp_common_t *ch;
	rtcp_fb_header_t *fbh;
	rtcp_fb_tmmbr_fci_t *fci;
	int length = 0;

	if (!rs->tmmbr_info.received) return 0;

	/* Fill TMMBN */
	ch = (rtcp_common_t *)&buf[length];
	length += sizeof(rtcp_common_t);
	fbh = (rtcp_fb_header_t *)&buf[length];
	length += sizeof(rtcp_fb_header_t);
	fci = (rtcp_fb_tmmbr_fci_t *)&buf[length];
	length += sizeof(rtcp_fb_tmmbr_fci_t);
	fbh->packet_sender_ssrc = rs->ssrc;
	fbh->media_source_ssrc = htonl(0);
	memcpy(fci, rtcp_rtpfb_tmmbr_get_fci(rs->tmmbr_info.received), sizeof(rtcp_fb_tmmbr_fci_t));
	fci->ssrc = htonl(ssrc);

	/* Fill common header */
	ch->p = 0;
	ch->version = 2;
	ch->pt = RTCP_RTPFB;
    ch->count = RTCP_RTPFB_TMMBN;
	ch->length = htons(length / 4 - 1);

	return length;
}


int rtp_state_get_tmmbr_wait_send_maxbitrate(rtp_state *rs, u__int64_t *mxtbr){
	if (rs->tmmbr_info.sent) {
		*mxtbr = rtcp_rtpfb_tmmbr_get_max_bitrate(rs->tmmbr_info.sent);
		return 0;
	}
	return -1;
}


static void handle_rtcp_rtpfb_packet(rtp_state *rs, const char *buf, int len) {
	rtcp_common_t *ch = (rtcp_common_t *)&buf[0];

	switch ((rtcp_rtpfb_type_t)ch->count) {
		case RTCP_RTPFB_TMMBR:
			if (rs->tmmbr_info.received) freemsg((char *)(rs->tmmbr_info.received));
			rs->tmmbr_info.received = copymsg(buf, len);
			rs->s.tmmbr_max_bitrate = rtcp_rtpfb_tmmbr_get_max_bitrate(buf);
		  	break;
	  case RTCP_RTPFB_TMMBN:
		  if (rs->tmmbr_info.sent) {
			  rtcp_fb_tmmbr_fci_t *tmmbn_fci = rtcp_rtpfb_tmmbr_get_fci((char *)buf);
			  rtcp_fb_tmmbr_fci_t *tmmbr_fci = rtcp_rtpfb_tmmbr_get_fci((char *)(rs->tmmbr_info.sent));
			  if ((tmmbn_fci->ssrc == rs->ssrc) && (tmmbn_fci->value == tmmbr_fci->value)) {
				  freemsg((char *)(rs->tmmbr_info.sent));
				  rs->tmmbr_info.sent = NULL;
			  }
		  }
		  break;
	  default:
		  break;
  }
}

static unsigned int report_block_get_fraction_lost(const rtcp_rr_t * rr) {
	return (ntohl(rr->fl_cnpl)>>24);
}

static unsigned int report_block_get_cum_packet_lost(const rtcp_rr_t * rr){
	unsigned int cum_loss = (unsigned int)ntohl(rr->fl_cnpl);
	if (((cum_loss>>23)&1)==0)
		return (unsigned int) (0x00FFFFFF & cum_loss);
	else
		return (unsigned int)(0xFF000000 | (cum_loss-0xFFFFFF-1));
}

static void compute_rtt_from_report_block(rtp_state *rs, const struct timeval *now, rtcp_rr_t *rr) {
	unsigned int last_sr_time;
	unsigned int sr_delay;
	
	u__int64_t curntp;
	unsigned int approx_ntp;

	last_sr_time = ntohl(rr->lsr);
	sr_delay = ntohl(rr->dlsr);
	curntp=rtp_timeval_to_ntp(now);
	approx_ntp=(curntp>>16) & 0xFFFFFFFF;
	//printf("compute_rtt_from_report_block, last_sr_time:%u sr_delay:%u, approx_ntp:%u", last_sr_time, sr_delay, approx_ntp);

	if (last_sr_time!=0 && sr_delay!=0){
		/*we cast to int32_t to check for crazy RTT time (negative)*/
		double rtt_frac=(unsigned int)(approx_ntp-last_sr_time-sr_delay);
		//printf("compute_rtt_from_report_block, rtt_frac:%lf", rtt_frac);
		if (rtt_frac>=0){
			rtt_frac/=65536.0;

			rs->s.rtt=(float)rtt_frac;
		}
	}

	rs->s.cum_loss = report_block_get_cum_packet_lost(rr);
	rs->s.fraction_lost = report_block_get_fraction_lost(rr);
}


/**
 * called when receive a peer's rtp data packet
 */
TOOLKIT_API int rtp_state_on_recv_rtcp(rtp_state *rs, const void *buf, int len)
{
	if (rs && buf && len >= sizeof(rtcp_common_t)) {
		int n  = 0;
		while( n < len) {
			const rtcp_common_t *common = (rtcp_common_t *)((const char*)buf + n);
			if (common->version != 2)
				return -1;
			n += sizeof(rtcp_common_t);
			if (common->pt == RTCP_SR) {
				rtcp_sender_info_t *si;
				si = (rtcp_sender_info_t *)((const char*)buf + n);
				rs->s.lsr = ( ntohl( si->ntp_sec ) << 16 ) | ( ntohl( si->ntp_frac ) >> 16 );
				conflict_gettimeofday(&rs->s.lsr_tm);
			}
			if ((common->pt == RTCP_SR || common->pt == RTCP_RR) && common->count) {
				rtcp_rr_t *rr;
				struct timeval now;
				conflict_gettimeofday(&now);
				
				if (common->pt == RTCP_SR)
					rr = rtcp_SR_get_report_block((const char*)buf);
				else {
					rr = rtcp_RR_get_report_block((const char*)buf);
				}
				
				if (rr != NULL){
					compute_rtt_from_report_block(rs, &now, rr);
					rs->s.report_block_last_number_of_packets = ntohl(rr->last_seq) - rs->s.report_block_last_seq;
					rs->s.report_block_last_seq = ntohl(rr->last_seq);
				}
			
			}
			if (rtcp_is_rtpfb((char *)common), rtcp_get_size((char *)common)) {
				handle_rtcp_rtpfb_packet(rs, (char *)common, rtcp_get_size((char *)common));
			}
			n += ntohs(common->length) * 4;
		}
		return 0;
	}
	return -1;
}

#define MAX_DROPOUT	3000
#define MAX_MISORDER 100
#define MIN_SEQUENTIAL 2

/**
 * called when receive a peer's rtp data packet
 */
TOOLKIT_API int rtp_state_on_recv_rtp(rtp_state *rs, const void *buf, int len)
{
	if (rs && buf && len >= sizeof(rtp_hdr)) {
		rtp_hdr *hdr = (rtp_hdr*)buf;
		unsigned short seq = ntohs(hdr->seq);
		if (rs->s.first_seq == 0 && rs->s.seq_circles == 0) {
			rs->s.first_seq = seq;
			rs->s.max_seq = seq;
			rs->s.peer_ssrc = hdr->ssrc;
			//rs->s.last_seq = seq;
		} else {
			unsigned short delta = seq - rs->s.max_seq;
			if (delta < MAX_DROPOUT) {
				if (seq < rs->s.max_seq)
					rs->s.seq_circles ++;
				rs->s.max_seq = seq;
			} else { 
				/* duplicated */
			}
		}
		//len -= sizeof(rtp_hdr);
		rs->s.total_rx_packets ++;
		rs->s.total_rx_bytes += len;
		rs->s.last_seq = seq;
		rs->s.rx_packets_since_last_sr++;
		return 0;
	}
	return -1;
}

/**
 * called when send rtp data packet out
 */
TOOLKIT_API int rtp_state_on_send_rtp(rtp_state *rs, int len)
{
	if (rs) {
		len -= sizeof(rtp_hdr);
		rs->s.total_tx_packets ++;
		rs->s.total_tx_bytes += len;
		return 0;
	}
	return -1;
}

/**
 * set sdes string, only ascii string less than 255 accepted
 */
TOOLKIT_API int rtp_state_set_sdes_str(rtp_state *rs, rtcp_sdes_type_t type, const char *str)
{
	char *t;
	if (!rs)
		return -1;
	if (str == NULL) {
		if (rs->sdes_str[type]) {
			free(rs->sdes_str[type]);
			rs->sdes_str[type] = NULL;
		}
		return 0;
	}
	t = (char*)malloc(RTP_MAX_SDES);
	if (!t)
		return -1;
	strncpy(t, str, RTP_MAX_SDES);
	t[RTP_MAX_SDES-1] = 0;
	if (rs->sdes_str[type])
		free(rs->sdes_str[type]);
	rs->sdes_str[type] = t;
	return 0;
}

// rtp_state_set_params();

TOOLKIT_API int rtp_state_reset(rtp_state *rs, 
					unsigned int ssrc, 
					unsigned int padding, 
					unsigned int extension)
{
	if (!rs)
		return -1;
	if (ssrc == 0)
		ssrc = (unsigned int)rand();
	rs->ssrc = htonl(ssrc);
	rs->p = !!padding;
	rs->x = !!extension;
	rs->ts = 0;
	rs->seq = 0;
	//.
	return 0;
}

TOOLKIT_API rtp_state *rtp_state_create(int transmit_interval)
{
	rtp_state *state;
	
	if (transmit_interval <= 0)
		transmit_interval = DEFAULT_RTP_STATE_TRANSMIT_INTERVAL;
	else if (transmit_interval > 5000)
		transmit_interval = 5000;
	
	state = malloc(sizeof(rtp_state));
	if (state) {
		memset(state, 0, sizeof(rtp_state));
		//..
		state->transmit_interval = (DWORD)transmit_interval;
		state->last_transmit_tick = 0;
	}
	return state;
}

TOOLKIT_API void rtp_state_destroy(rtp_state *rs)
{
	if (rs) {
		int i;
		for (i = 0; i < RTCP_SDES_COUNT; ++i) {
			if (rs->sdes_str[i])
				free(rs->sdes_str[i]);
		}
		free(rs);
	}
}

TOOLKIT_API int rtp_state_get_stat(rtp_state *rs, rtcp_statistics *stat)
{
	if (rs && stat) {
		memcpy(stat, &rs->s, sizeof(rtcp_statistics));
		return 0;
	} 
	return -1;
}

TOOLKIT_API int rtp_state_need_send_rtcp(rtp_state *state, int update_ticks)
{
	DWORD now;
	DWORD diff;

	assert(state);

	now = GetTickCount();
	diff = now - state->last_transmit_tick;

	if (diff >= state->transmit_interval) {
		if (update_ticks)
			state->last_transmit_tick = now;
		return 1;
	} else {
		return 0;
	}
}

TOOLKIT_API void rtp_state_update_send_rtcp_ticks(rtp_state *state)
{
	assert(state);
	state->last_transmit_tick = GetTickCount();
}