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decoder.cc

/*
 * 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
 *    specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
static const char rcsid[] =
    "@(#) $Header: decoder.cc,v 1.9 96/04/09 01:36:14 van Exp $ (LBL)";

#include <stdlib.h>
#include "decoder.h"
#include "controller.h"

#define     INITIAL_OFFSET (4*FRAMESIZE)


static class PCM_DecoderMatcher : public Matcher {
    public:
      PCM_DecoderMatcher() : Matcher("decoder") {}
      TclObject* match(const char* fmt) {
            if (strcasecmp(fmt, "pcm") == 0)
                  return (new PCM_Decoder);
            else
                  return (0);
      }
} pcm_decoder_matcher;

Decoder::Decoder() :
      PacketHandler(0),
      nstat_(0),
      controller_(0),
      var_(INITIAL_OFFSET << (VAR_FILTER - VAR_MULT)),
      hostoffset_(0),
      predicted_drop_(~0),
      playout_(INITIAL_OFFSET << PLAYO_FILTER),
      lastrecv_(0),
      lecture_mode_(0),
      framesize_(FRAMESIZE), /*XXX*/
      block_size_(FRAMESIZE),
      maxdel_(0)
{
      for (int i = 0; i < MAXSTAT; ++i) {
            stat_[i].name = 0;
            stat_[i].cnt = 0;
      }
#define STAT_LATE 0
      stat_[STAT_LATE].name = "Late-Pkts";
      nstat_ = 1;
}

Decoder::~Decoder()
{
}

void Decoder::info(char* wrk) const
{
      *wrk = 0;
}

void Decoder::stats(char* bp)
{
      if (nstat_ == 0) {
            *bp = 0;
            return;
      }
      for (int i = 0; i < nstat_; ++i) {
            sprintf(bp, "%s %d ", stat_[i].name, stat_[i].cnt);
            bp += strlen(bp);
      }
      bp[-1] = 0;
}

int Decoder::command(int argc, const char*const* argv)
{
      Tcl& tcl = Tcl::instance();
      if (argc == 2) {
            char* bp = tcl.buffer();
            if (strcmp(argv[1], "info") == 0) {
                  info(bp);
                  tcl.result(bp);
                  return (TCL_OK);
            }
            if (strcmp(argv[1], "stats") == 0) {
                  stats(bp);
                  tcl.result(bp);
                  return (TCL_OK);
            }
            if (strcmp(argv[1], "block-size") == 0) {
                  sprintf(bp, "%u", block_size_);
                  tcl.result(bp);
                  return (TCL_OK);
            }
            if (strcmp(argv[1], "playout") == 0) {
                  sprintf(bp, "%u", playout());
                  tcl.result(bp);
                  return (TCL_OK);
            }
            if (strcmp(argv[1], "reset-offset") == 0) {
                  hostoffset_ = 0;
                  var_ = 0;
                  playout_ = 0;
                  return (TCL_OK);
            }
      } else if (argc == 3) {
            if (strcmp(argv[1], "controller") == 0) {
                  controller_ = (Controller*)TclObject::lookup(argv[2]);
                  maxdel_ = controller_->maxdel();
                  return (TCL_OK);
            }
            if (strcmp(argv[1], "lecture-mode") == 0) {
                  lecture_mode_ = atoi(argv[2]);
                  return (TCL_OK);
            }
      }
      return (TclObject::command(argc, argv));
}

void PCM_Decoder::recv(const struct rtphdr* rh, const u_int8_t* data, int len)
{
      if (active())
            consume_samples(rh, data, len);
}

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 Decoder::adapt(const rtphdr* rh, u_int32_t local_clock)
{
      register u_int32_t tstamp = ntohl(rh->rh_ts);
      register int hoff = (int)hostoffset_;
      register int offset = (tstamp + hoff - local_clock) &~ 3;
      int new_ts = rh->rh_flags & htons(RTP_M);
      if (hoff == 0 || new_ts) {
            /*
             * 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.
                   */
                  if (new_ts) {
                        offset -= 4 * FRAMESIZE;
                        if (offset < block_size_)
                              offset = block_size_;
                  }
            }
            hostoffset_ = local_clock - tstamp + offset;
      } else if (offset < 0 || offset > maxdel_) {
            /*
             * 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 {
                  predicted_drop_ = tstamp + block_size_;
                  lastrecv_ = tstamp - local_clock;
                  count(STAT_LATE);
                  return (-1);
            }
      } else {
            // packet in range, update interarrival var. est.
            register int nvar = var_;
            register int off = tstamp - local_clock - lastrecv_;
            if (off < 0)
                  off = -off;
            off -= (nvar >> VAR_FILTER);
            var_ = nvar + off;
      }
      lastrecv_ = tstamp - local_clock;
      register u_int avgplay = playout_;
      playout_ = avgplay + (offset - (avgplay >> PLAYO_FILTER));
      offset &= ~3;
      delvar_ = var_ >> VAR_FILTER;
      return (offset);
}

/*
 * Dummy class for streams that we recognize but cannot decode (for lack
 * of software support).  We still want to put all the stats etc. --
 * especially the format -- but can't decode it.  XXX We need to somehow
 * mark the stream in the user-interface so that the user knows that
 * vic cannot decode the stream (to avoid assuming something else is
 * wrong with the tranmission)
 */
class NullDecoder : public Decoder {
    public:
      virtual void recv(const struct rtphdr*, const u_char*, int) {}
};

static class NullDecoderMatcher : public Matcher {
    public:
      NullDecoderMatcher() : Matcher("decoder") {}
      TclObject* match(const char* id) {
            if (strcasecmp(id, "null") == 0)
                  return (new NullDecoder());
            else
                  return (0);
      }
} dm_null;


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