rfc3984.c 8.6 KB
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/*
mediastreamer2 library - modular sound and video processing and streaming
Copyright (C) 2006  Simon MORLAT (simon.morlat@linphone.org)

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

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#include "mediastreamer2/rfc3984.h"
#include "mediastreamer2/msfilter.h"

#define TYPE_FU_A 28    /*fragmented unit 0x1C*/
#define TYPE_STAP_A 24  /*single time aggregation packet  0x18*/


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static MS2_INLINE void nal_header_init(uint8_t *h, uint8_t nri, uint8_t type){
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	*h=((nri&0x3)<<5) | (type & ((1<<5)-1));
}

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static MS2_INLINE uint8_t nal_header_get_type(const uint8_t *h){
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	return (*h) & ((1<<5)-1);
}

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static MS2_INLINE uint8_t nal_header_get_nri(const uint8_t *h){
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	return ((*h) >> 5) & 0x3;
}

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Rfc3984Context *rfc3984_new(void){
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	Rfc3984Context *ctx=ms_new0(Rfc3984Context,1);
	rfc3984_init(ctx);
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	return ctx;
}

void rfc3984_destroy(Rfc3984Context *ctx){
	rfc3984_uninit (ctx);
	ms_free(ctx);
}

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void rfc3984_init(Rfc3984Context *ctx){
	ms_queue_init(&ctx->q);
	ctx->m=NULL;
	ctx->maxsz=ms_get_payload_max_size();
	ctx->mode=0;
	ctx->last_ts=0x943FEA43;/*some random value*/
	ctx->stap_a_allowed=TRUE;
}

void rfc3984_set_max_payload_size(Rfc3984Context *ctx, int size){
	ctx->maxsz=size;
}

static void send_packet(MSQueue *rtpq, uint32_t ts, mblk_t *m, bool_t marker){
	mblk_set_timestamp_info(m,ts);
	mblk_set_marker_info(m,marker);
	ms_queue_put(rtpq,m);
}

static void put_nal_size(mblk_t *m, uint16_t sz){
	uint16_t size=htons(sz);
	*(uint16_t*)m->b_wptr=size;
	m->b_wptr+=2;
}

static mblk_t * prepend_stapa(mblk_t *m){
	mblk_t *hm=allocb(3,0);
	nal_header_init(hm->b_wptr,nal_header_get_nri(m->b_rptr),TYPE_STAP_A);
	hm->b_wptr+=1;
	put_nal_size(hm,msgdsize(m));
	hm->b_cont=m;
	return hm;
}

static mblk_t * concat_nalus(mblk_t *m1, mblk_t *m2){
	mblk_t *l=allocb(2,0);
	/*eventually append a stap-A header to m1, if not already done*/
	if (nal_header_get_type(m1->b_rptr)!=TYPE_STAP_A){
		m1=prepend_stapa(m1);
	}
	put_nal_size(l,msgdsize(m2));
	l->b_cont=m2;
	concatb(m1,l);
	return m1;
}

static mblk_t *prepend_fu_indicator_and_header(mblk_t *m, uint8_t indicator,
	bool_t start, bool_t end, uint8_t type){
	mblk_t *h=allocb(2,0);
	h->b_wptr[0]=indicator;
	h->b_wptr[1]=((start&0x1)<<7)|((end&0x1)<<6)|type;
	h->b_wptr+=2;
	h->b_cont=m;
	if (start) m->b_rptr++;/*skip original nalu header */
	return h;
}

static void frag_nalu_and_send(MSQueue *rtpq, uint32_t ts, mblk_t *nalu, bool_t marker, int maxsize){
	mblk_t *m;
	int payload_max_size=maxsize-2;/*minus FUA header*/
	uint8_t fu_indicator;
	uint8_t type=nal_header_get_type(nalu->b_rptr);
	uint8_t nri=nal_header_get_nri(nalu->b_rptr);
	bool_t start=TRUE;

	nal_header_init(&fu_indicator,nri,TYPE_FU_A);
	while(nalu->b_wptr-nalu->b_rptr>payload_max_size){
		m=dupb(nalu);
		nalu->b_rptr+=payload_max_size;
		m->b_wptr=nalu->b_rptr;
		m=prepend_fu_indicator_and_header(m,fu_indicator,start,FALSE,type);
		send_packet(rtpq,ts,m,FALSE);
		start=FALSE;
	}
	/*send last packet */
	m=prepend_fu_indicator_and_header(nalu,fu_indicator,FALSE,TRUE,type);
	send_packet(rtpq,ts,m,marker);
}

static void rfc3984_pack_mode_0(Rfc3984Context *ctx, MSQueue *naluq, MSQueue *rtpq, uint32_t ts){
	mblk_t *m;
	bool_t end;
	int size;
	while((m=ms_queue_get(naluq))!=NULL){
		end=ms_queue_empty(naluq);
		size=m->b_wptr-m->b_rptr;
		if (size>ctx->maxsz){
			ms_warning("This H264 packet does not fit into mtu: size=%i",size);
		}
		send_packet(rtpq,ts,m,end);
	}
}

/*process NALUs and pack them into rtp payloads */
static void rfc3984_pack_mode_1(Rfc3984Context *ctx, MSQueue *naluq, MSQueue *rtpq, uint32_t ts){
	mblk_t *m,*prevm=NULL;
	int prevsz=0,sz;
	bool_t end;
	while((m=ms_queue_get(naluq))!=NULL){
		end=ms_queue_empty(naluq);
		sz=m->b_wptr-m->b_rptr;
		if (ctx->stap_a_allowed){
			if (prevm!=NULL){
				if ((prevsz+sz)<(ctx->maxsz-2)){
					prevm=concat_nalus(prevm,m);
					m=NULL;
					prevsz+=sz+2;/*+2 for the stapa size field*/
					continue;
				}else{
					/*send prevm packet: either single nal or STAP-A*/
					if (prevm->b_cont!=NULL){
						ms_debug("Sending STAP-A");
					}else
						ms_debug("Sending previous msg as single NAL");
					send_packet(rtpq,ts,prevm,FALSE);
					prevm=NULL;
					prevsz=0;
				}
			}
			if (sz<(ctx->maxsz/2)){
				/*try to aggregate it with next packet*/
				prevm=m;
				prevsz=sz+3; /*STAP-A header + size*/
				m=NULL;
			}else{
				
				/*send as single nal or FU-A*/
				if (sz>ctx->maxsz){
					ms_debug("Sending FU-A packets");
					frag_nalu_and_send(rtpq,ts,m,end, ctx->maxsz);
				}else{
					ms_debug("Sending Single NAL");
					send_packet(rtpq,ts,m,end);
				}
			}
		}else{
			if (sz>ctx->maxsz){
				ms_debug("Sending FU-A packets");
				frag_nalu_and_send(rtpq,ts,m,end, ctx->maxsz);
			}else{
				ms_debug("Sending Single NAL");
				send_packet(rtpq,ts,m,end);
			}
		}
	}
	if (prevm){
		ms_debug("Sending Single NAL (2)");
		send_packet(rtpq,ts,prevm,TRUE);
	}
}

static mblk_t * aggregate_fua(Rfc3984Context *ctx, mblk_t *im){
	mblk_t *om=NULL;
	uint8_t fu_header;
	uint8_t nri,type;
	bool_t start,end;
	fu_header=im->b_rptr[1];
	type=nal_header_get_type(&fu_header);
	start=fu_header>>7;
	end=(fu_header>>6)&0x1;
	if (start){
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		mblk_t *new_header;
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		nri=nal_header_get_nri(im->b_rptr);
		if (ctx->m!=NULL){
			ms_error("receiving FU-A start while previous FU-A is not "
				"finished");
			freemsg(ctx->m);
			ctx->m=NULL;
		}
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		im->b_rptr+=2; /*skip the nal header and the fu header*/
		new_header=allocb(1,0); /* allocate small fragment to put the correct nal header, this is to avoid to write on the buffer
					which can break processing of other users of the buffers */
		nal_header_init(new_header->b_wptr,nri,type);
		new_header->b_wptr++;
		mblk_meta_copy(im,new_header);
		concatb(new_header,im);
		ctx->m=new_header;
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	}else{
		if (ctx->m!=NULL){
			im->b_rptr+=2;
			concatb(ctx->m,im);
		}else{
			ms_error("Receiving continuation FU packet but no start.");
			freemsg(im);
		}
	}
	if (end && ctx->m){
		msgpullup(ctx->m,-1);
		om=ctx->m;
		ctx->m=NULL;
	}
	return om;
}

/*process incoming rtp data and output NALUs, whenever possible*/
void rfc3984_unpack(Rfc3984Context *ctx, mblk_t *im, MSQueue *out){
	uint8_t type=nal_header_get_type(im->b_rptr);
	uint8_t *p;
	int marker = mblk_get_marker_info(im);
	uint32_t ts=mblk_get_timestamp_info(im);

	if (ctx->last_ts!=ts){
		/*a new frame is arriving, in case the marker bit was not set in previous frame, output it now*/
		/* unless this is a FU-A (workarond some other apps bugs)*/
		ctx->last_ts=ts;
		if (ctx->m==NULL){
			while(!ms_queue_empty(&ctx->q)){
				ms_queue_put(out,ms_queue_get(&ctx->q));
			}
		}
	}

	if (im->b_cont) msgpullup(im,-1);

	if (type==TYPE_STAP_A){
		/*split into nalus*/
		uint16_t sz;
		uint8_t *buf=(uint8_t*)&sz;
		mblk_t *nal;
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		ms_debug("Receiving STAP-A");
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		for(p=im->b_rptr+1;p<im->b_wptr;){
			buf[0]=p[0];
			buf[1]=p[1];
			sz=ntohs(sz);
			nal=dupb(im);
			p+=2;
			nal->b_rptr=p;
			p+=sz;
			nal->b_wptr=p;
			if (p>im->b_wptr){
				ms_error("Malformed STAP-A packet");
				freemsg(nal);
				break;
			}
			ms_queue_put(&ctx->q,nal);
		}
		freemsg(im);
	}else if (type==TYPE_FU_A){
		mblk_t *o=aggregate_fua(ctx,im);
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		ms_debug("Receiving FU-A");
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		if (o) ms_queue_put(&ctx->q,o);
	}else{
		if (ctx->m){
			/*discontinued FU-A, purge it*/
			freemsg(ctx->m);
			ctx->m=NULL;
		}
		/*single nal unit*/
		ms_debug("Receiving single NAL");
		ms_queue_put(&ctx->q,im);
	}

	if (marker){
		ctx->last_ts=ts;
		ms_debug("Marker bit set");
		/*end of frame, output everything*/
		while(!ms_queue_empty(&ctx->q)){
			ms_queue_put(out,ms_queue_get(&ctx->q));
		}
	}
}


void rfc3984_pack(Rfc3984Context *ctx, MSQueue *naluq, MSQueue *rtpq, uint32_t ts){
	switch(ctx->mode){
		case 0:
			rfc3984_pack_mode_0(ctx,naluq,rtpq,ts);
			break;
		case 1:
			rfc3984_pack_mode_1(ctx,naluq,rtpq,ts);
			break;
		default:
			ms_error("Bad or unsupported mode %i",ctx->mode);
	}
}

void rfc3984_uninit(Rfc3984Context *ctx){
	ms_queue_flush(&ctx->q);
	if (ctx->m) freemsg(ctx->m);
	ctx->m=NULL;
}

void rfc3984_set_mode(Rfc3984Context *ctx, int mode){
	ctx->mode=mode;
}

void rfc3984_enable_stap_a(Rfc3984Context *ctx, bool_t yesno){
	ctx->stap_a_allowed=yesno;
}