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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 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
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/*
 * 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
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 *    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
 *    specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
*/

#ifndef lint
static const char  rcsid[] =
"@(#) $Header: /nfs/jade/vint/CVSROOT/ns-2/apps/vatrcvr.cc,v 1.7 2005/08/26 05:05:28 tomh 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;
}

---