vatrcvr.cc

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/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) Xerox Corporation 1997. All rights reserved.
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 * FOR ANY PARTICULAR PURPOSE.  The software is provided "as is" without
 * express or implied warranty of any kind.
 *
 * These notices must be retained in any copies of any part of this
 * software. 
 */

/*
 * Copyright (c) 1995 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the Network Research
 *      Group at Lawrence Berkeley National Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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*/

#ifndef lint
static const char  rcsid[] =
"@(#) $Header: /nfs/jade/vint/CVSROOT/ns-2/apps/vatrcvr.cc,v 1.6 2000/09/01 03:04:08 haoboy Exp $";
#endif

#ifndef WIN32
#include <sys/time.h>
#endif
#include "agent.h"
#include "rtp.h"
#include "adaptive-receiver.h"
#include "vat.h"

//Most of this code is taken from the decoder.cc file of the publicly available
//vat code with some minor midifications.

class VatRcvr : public AdaptiveRcvr {
public:
        VatRcvr();
protected:
        int adapt(Packet *pkt, u_int32_t time);
        void count(int statno);
        u_int32_t hostoffset_;
        int32_t var_; //variance in  this host's interarrival time
        u_int32_t playout_; // playout delay (in media units)
        int maxdel_;
        int block_size_;
        int lecture_mode_;
        u_int32_t lastrecv_;
        u_int32_t predicted_drop_;
        int delvar_;
        /*XXX*/
#define MAXSTAT 16
        struct statcntr {
                const char* name;
                u_int cnt;
        } stat_[MAXSTAT];
        int nstat_;
};


inline void VatRcvr::count(int statno)
{
        ++stat_[statno].cnt;
}


inline int absdiff(int x, int y)
{
        register int r = y - x;
        return (r < 0? -r : r);
}

static inline int newoffset(
        int nvar,
        int playout,
        int maxdel, int mindel, int lecture)
{
        register int offset = nvar;
        if (offset > maxdel)
                offset = maxdel;
        register int diff = playout - offset;

        if (diff > 0) {
                // offset going down: in LectureMode, drop at most
                // one frametime per talkspurt.  In ConferenceMode,
                // drop at most 1/2 of difference.
                if (lecture) {
                        if (diff > FRAMESIZE) {
                                if (playout > (maxdel * 3) / 4 &&
                                    diff > 10 * FRAMESIZE)
                                        diff = 5 * FRAMESIZE;
                                else
                                        diff = FRAMESIZE;
                        }
                } else
                        diff >>= 1;
                offset = playout - diff;
        } else if (-diff > maxdel) {
                // offset going way up: only allow 3/4 of max.
                offset = (maxdel * 3) / 4;
        }
        if (offset > (maxdel * 7) / 8)
                offset = (maxdel * 7) / 8;
        else if (offset < mindel)
                offset = mindel;
        return (offset);
}



int VatRcvr::adapt(Packet *pkt, u_int32_t local_clock)
{
        hdr_cmn* ch = hdr_cmn::access(pkt);
        register u_int32_t tstamp = (int)ch->timestamp();
        register int hoff = (int)hostoffset_;
        register int offset = (tstamp + hoff - local_clock) &~ 3;
        hdr_rtp *rh = hdr_rtp::access(pkt);
        int new_ts = rh->flags() & RTP_M ;

        //struct timeval tv;
        //static long int last;
        
        /*    printf("%1d %10d %10d\n", new_ts ? 1: 0, tstamp, local_clock);*/
        
        /* printf("%u\n", tstamp); */
        
        //gettimeofday(&tv, NULL);
        //last = tv.tv_usec - last;
        //if (last < 0)
        //      last += 1000000;
        /*
          printf("%u %u %u ==> %d\n", tstamp, hoff, local_clock, offset);
          printf("%u %d\n", tv.tv_usec, last);
          */
        //last = tv.tv_usec;
        /* printf("%u ==> %d\n", local_clock, offset); */
        
        if (hoff == 0 || new_ts) {
                /*  if (hoff == 0) {  */
                
                /* printf("TS: var = %d playback = %d", var_ >> (VAR_FILTER + 3), 
                   playout_ >> (PLAYO_FILTER + 3)); */
                /*
                 * start of new talk spurt --
                 * use accumulated variance to compute new offset if
                 * this would make a significant change.  We change if
                 *  - the variance is currently 'small', or
                 *  - the change would be a least a packet time
                 */
                register int nvar = var_ >> (VAR_FILTER - VAR_MULT);
                offset = playout_ >> PLAYO_FILTER;
                if (nvar < 3*FRAMESIZE || absdiff(nvar, offset) >= FRAMESIZE) {
                        offset = newoffset(nvar, offset, maxdel_, 
                                           block_size_, lecture_mode_);
                        /*
                         * assume that a talk spurt starts with TALK_LEAD
                         * samples of history & subtract them off if possible.
                         */
                        
                        /* CHANGED THIS PART OF VAT CODE AS WELL */
                        if (new_ts) {
                                offset -= 4 * FRAMESIZE;
                                if (offset < block_size_)
                                        offset = block_size_;
                                
                        }
                }
                hostoffset_ = local_clock - tstamp + offset;
                /* printf(" new playback = %d\n", offset >> 3); */
        } else if (offset < 0 || offset > maxdel_) {
                /* printf("LP: late by %d var = %d playback = %d", (0 - (offset >> 3)), 
                   var_ >> (VAR_FILTER + 3), playout_ >> (PLAYO_FILTER + 3)); */
                /*
                 * packet out of range -- if last packet also out of
                 * range or if the delay would increase, resync.
                 */
                if (offset < 0 || predicted_drop_ == tstamp) {
                        offset = newoffset(var_ >> (VAR_FILTER - VAR_MULT),
                                           playout_ >> PLAYO_FILTER,
                                           maxdel_, block_size_,
                                           lecture_mode_);
                        hostoffset_ = local_clock - tstamp + offset;
                } else {
                        /* printf("late packet\n"); */
                        predicted_drop_ = tstamp + block_size_;
                        lastrecv_ = tstamp - local_clock;
                        count(STAT_LATE);
                        return (-1);
                }
                /* printf(" new playback = %d\n", offset >> 3); */
        } else {
                // packet in range, update interarrival var. est.
                register int nvar = var_;
                register int off = tstamp - local_clock - lastrecv_;
                /* printf("offset =  %3d", off >> 3);  */
                if (off < 0)
                        off = -off;
                off -= (nvar >> VAR_FILTER);
                var_ = nvar + off;
                /* printf(" var =  %3d", var_ >> 8);  */
        }
        lastrecv_ = tstamp - local_clock;
        register u_int avgplay = playout_;
        playout_ = avgplay + (offset - (avgplay >> PLAYO_FILTER));
        /* printf(" offset = %3d avg playout = %3d", offset >> 3, playout_ >> 8);  */
        offset &= ~3;
        delvar_ = var_ >> VAR_FILTER;
        /* printf("\n"); */
        return (offset);
        
}



static class VatRcvrClass : public TclClass {
public:
        VatRcvrClass() : TclClass("Agent/VatRcvr") {}
        TclObject* create(int, const char*const*) {
                return (new VatRcvr());

        }
} class_vat_rcvr;


VatRcvr::VatRcvr() : 
        hostoffset_(0),
        var_(INITIAL_OFFSET << (VAR_FILTER - VAR_MULT)),
        playout_(INITIAL_OFFSET << PLAYO_FILTER),
        maxdel_(8000*6),
        block_size_(FRAMESIZE),
        lecture_mode_(0),
        lastrecv_(0),
        predicted_drop_(~0),
        nstat_(0)
{

        for (int i = 0; i < MAXSTAT; ++i) {
                stat_[i].name = 0;
                stat_[i].cnt = 0;
        }
        stat_[STAT_LATE].name = "Late-Pkts";
        nstat_ = 1;
}

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