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A set of basic utilities used in Jitsi projects
/*
* Copyright @ 2015 Atlassian Pty Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jitsi.utils.dsi;
import java.lang.ref.*;
import java.time.*;
import java.util.*;
import java.util.concurrent.*;
import org.jetbrains.annotations.*;
import org.jitsi.utils.concurrent.*;
import org.jitsi.utils.logging2.*;
import org.json.simple.*;
/**
* Implements {@link ActiveSpeakerDetector} with inspiration from the paper
* "Dominant Speaker Identification for Multipoint Videoconferencing"
* by Ilana Volfin and Israel Cohen.
*
* @param The type used for speaker identifiers.
*
* @author Lyubomir Marinov
*/
@SuppressWarnings("unused")
public class DominantSpeakerIdentification
extends AbstractActiveSpeakerDetector
{
/**
* The threshold of the relevant speech activities in the immediate
* time-interval in "global decision"/"Dominant speaker
* selection" phase of the algorithm.
*/
private static final double C1 = 3;
/**
* The threshold of the relevant speech activities in the medium
* time-interval in "global decision"/"Dominant speaker
* selection" phase of the algorithm.
*/
private static final double C2 = 2;
/**
* The threshold of the relevant speech activities in the long
* time-interval in "global decision"/"Dominant speaker
* selection" phase of the algorithm.
*/
private static final double C3 = 0;
/**
* The indicator which determines whether the
* DominantSpeakerIdentification class and its instances are to
* execute in debug mode.
*/
private static final boolean DEBUG;
/**
* The interval in milliseconds of the activation of the identification of
* the dominant speaker in a multipoint conference.
*/
private static final long DECISION_INTERVAL = 300;
/**
* The interval of time in milliseconds of idle execution of
* DecisionMaker after which the latter should cease to exist. The
* interval does not have to be very long because the background threads
* running the DecisionMakers are pooled anyway.
*/
private static final long DECISION_MAKER_IDLE_TIMEOUT = 15 * 1000;
/**
* The interval of time without a call to {@link Speaker#levelChanged(int,long)}
* after which DominantSpeakerIdentification assumes that there
* will be no report of a Speaker's level within a certain
* time-frame. The default value of 40 is chosen in order to allow
* non-aggressive fading of the last received or measured level and to be
* greater than the most common RTP packet durations in milliseconds i.e.
* 20 and 30.
*/
private static final long LEVEL_IDLE_TIMEOUT = 40;
/**
* The Logger used by the DominantSpeakerIdentification
* class and its instances to print debug information.
*/
private static final Logger logger = new LoggerImpl(DominantSpeakerIdentification.class.getName());
/**
* The (total) number of long time-intervals used for speech activity score
* evaluation at a specific time-frame.
*/
private static final int LONG_COUNT = 1;
/**
* The threshold in terms of active medium-length blocks which is used
* during the speech activity evaluation step for the long time-interval.
*/
private static final int LONG_THRESHOLD = 4;
/**
* The maximum value of audio level supported by
* DominantSpeakerIdentification.
*/
private static final int MAX_LEVEL = 127;
/**
* The minimum value of audio level supported by
* DominantSpeakerIdentification.
*/
private static final int MIN_LEVEL = 0;
/**
* The number of (audio) levels received or measured for a Speaker
* to be monitored in order to determine that the minimum level for the
* Speaker has increased.
*/
private static final int MIN_LEVEL_WINDOW_LENGTH
= 15 /* seconds */ * 1000 /* milliseconds */
/ 20 /* milliseconds per level */;
/**
* The minimum value of speech activity score supported by
* DominantSpeakerIdentification. The value must be positive
* because (1) we are going to use it as the argument of a logarithmic
* function and the latter is undefined for negative arguments and (2) we
* will be dividing by the speech activity score.
*/
private static final double MIN_SPEECH_ACTIVITY_SCORE = 0.0000000001D;
/**
* The threshold in terms of active sub-bands in a frame which is used
* during the speech activity evaluation step for the medium length
* time-interval.
*/
private static final int MEDIUM_THRESHOLD = 7;
/**
* The (total) number of sub-bands in the frequency range evaluated for
* immediate speech activity. The implementation of the class
* DominantSpeakerIdentification does not really operate on the
* representation of the signal in the frequency domain, it works with audio
* levels derived from RFC 6465 "A Real-time Transport Protocol (RTP)
* Header Extension for Mixer-to-Client Audio Level Indication".
*/
private static final int N1 = 13;
/**
* The length/size of a sub-band in the frequency range evaluated for
* immediate speech activity. In the context of the implementation of the
* class DominantSpeakerIdentification, it specifies the
* length/size of a sub-unit of the audio level range defined by RFC 6465.
*/
private static final int N1_SUBUNIT_LENGTH = (MAX_LEVEL - MIN_LEVEL + N1 - 1) / N1;
/**
* The number of frames (i.e. {@link Speaker#immediates} evaluated for
* medium speech activity.
*/
private static final int N2 = 5;
/**
* The number of medium-length blocks constituting a long time-interval.
*/
private static final int N3 = 10;
/**
* The interval of time without a call to {@link Speaker#levelChanged(int,long)}
* after which DominantSpeakerIdentification assumes that a
* non-dominant Speaker is to be automatically removed from
* {@link #speakers}.
*/
private static final long SPEAKER_IDLE_TIMEOUT = 60 * 60 * 1000;
private static final ScheduledExecutorService DEFAULT_EXECUTOR
= Executors.newScheduledThreadPool(1, new CustomizableThreadFactory("dsi", true));
static
{
DEBUG = logger.isDebugEnabled();
}
/**
* Computes the binomial coefficient indexed by n and r
* i.e. the number of ways of picking r unordered outcomes from
* n possibilities.
*
* @param n the number of possibilities to pick from
* @param r the number unordered outcomes to pick from n
* @return the binomial coefficient indexed by n and r
* i.e. the number of ways of picking r unordered outcomes from
* n possibilities
*/
private static long binomialCoefficient(int n, int r)
{
int m = n - r; // r = Math.max(r, n - r);
if (r < m)
{
r = m;
}
long t = 1;
for (int i = n, j = 1; i > r; i--, j++)
{
t = t * i / j;
}
return t;
}
private static boolean computeBigs(
byte[] littles,
byte[] bigs,
int threshold)
{
int bigLength = bigs.length;
int littleLengthPerBig = littles.length / bigLength;
boolean changed = false;
for (int b = 0, l = 0; b < bigLength; b++)
{
byte sum = 0;
for (int lEnd = l + littleLengthPerBig; l < lEnd; l++)
{
if (littles[l] > threshold)
{
sum++;
}
}
if (bigs[b] != sum)
{
bigs[b] = sum;
changed = true;
}
}
return changed;
}
private static double computeSpeechActivityScore(
int vL,
int nR,
double lambda)
{
double p = 0.5;
double speechActivityScore
= Math.log(binomialCoefficient(nR, vL)) + vL * Math.log(p)
+ (nR - vL) * Math.log(1 - p) - Math.log(lambda) + lambda * vL;
if (speechActivityScore < MIN_SPEECH_ACTIVITY_SCORE)
{
speechActivityScore = MIN_SPEECH_ACTIVITY_SCORE;
}
return speechActivityScore;
}
/**
* The background task which repeatedly makes the (global) decision about speaker switches.
*/
private DecisionMaker decisionMaker;
/**
* The identifier of the dominant speaker.
*/
private T dominantId;
/**
* The last/latest time at which this DominantSpeakerIdentification
* made a (global) decision about speaker switches. The (global) decision
* about switcher switches should be made every {@link #DECISION_INTERVAL}
* milliseconds.
*/
private long lastDecisionTime;
/**
* The time in milliseconds of the most recent (audio) level report or
* measurement (regardless of the Speaker).
*/
private long lastLevelChangedTime;
/**
* The last/latest time at which this DominantSpeakerIdentification
* notified the Speakers who have not received or measured audio
* levels for a certain time (i.e. {@link #LEVEL_IDLE_TIMEOUT}) that they
* will very likely not have a level within a certain time-frame of the
* algorithm.
*/
private long lastLevelIdleTime;
/**
* The relative speech activities for the immediate, medium and long
* time-intervals, respectively, which were last calculated for a
* Speaker. Simply reduces the number of allocations and the
* penalizing effects of the garbage collector.
*/
private final double[] relativeSpeechActivities = new double[3];
/**
* The Speakers in the multipoint conference associated with this
* ActiveSpeakerDetector.
*/
private final Map> speakers = new HashMap<>();
/**
* The special ID to use to indicate silence (no speakers).
*
* When set to null silence detection is disabled.
*/
private final boolean enableSilence;
/**
* The interval (in milliseconds) of no activity before switching to {@code silence} (if silence detection is
* enabled).
*/
private final long timeoutToSilenceInterval;
/**
* The Speakers in the multipoint conference with the highest
* current energy levels.
*/
private final ArrayList> loudest = new ArrayList<>();
private final Clock clock;
/**
* The executor used to schedule {@link #decisionMaker}.
*/
private final ScheduledExecutorService executor;
/**
* The number of current loudest speakers to keep track of.
*/
private int numLoudestToTrack = 0;
/**
* Time in milliseconds after which speaker is removed from loudest list if
* no new audio packets have been received from that speaker.
*/
private int energyExpireTimeMs = 150;
/**
* Alpha factor for exponential smoothing of energy values, multiplied by 100.
*/
private int energyAlphaPct = 50;
/**
* Initializes a new DominantSpeakerIdentification instance.
*/
public DominantSpeakerIdentification()
{
this(Clock.systemUTC(), DEFAULT_EXECUTOR);
}
public DominantSpeakerIdentification(long silenceTimeout)
{
this(Clock.systemUTC(), DEFAULT_EXECUTOR, silenceTimeout);
}
public DominantSpeakerIdentification(Clock clock, ScheduledExecutorService executor)
{
this(clock, executor, -1);
}
/**
*
* @param clock The clock to use
* @param executor The executor in which to schedule periodic decision-making.
* @param silenceTimeout the interval of no speech after which we switch to silence (fire an event with active
* speaker {@code null}. A negative value means that silence detection is disabled and the speaker is always
* non-null (as long as there are any speakers in the conference).
*/
public DominantSpeakerIdentification(Clock clock, ScheduledExecutorService executor, long silenceTimeout)
{
this.clock = clock;
this.executor = executor;
this.timeoutToSilenceInterval = silenceTimeout;
enableSilence = silenceTimeout > 0;
}
/**
* Set energy ranking options
*/
public synchronized void setLoudestConfig(int numLoudestToTrack_, int energyExpireTimeMs_, int energyAlphaPct_)
{
numLoudestToTrack = numLoudestToTrack_;
energyExpireTimeMs = energyExpireTimeMs_;
energyAlphaPct = energyAlphaPct_;
logger.trace(() -> "numLoudestToTrack = " + numLoudestToTrack);
logger.trace(() -> "energyExpireTimeMs = " + energyExpireTimeMs);
logger.trace(() -> "energyAlphaPct = " + energyAlphaPct);
while (loudest.size() > numLoudestToTrack)
loudest.remove(numLoudestToTrack);
}
/**
* Notifies this DominantSpeakerIdentification instance that a
* specific DecisionMaker has permanently stopped executing (in its
* background/daemon Thread). If the specified
* decisionMaker is the one utilized by this
* DominantSpeakerIdentification instance, the latter will update
* its state to reflect that the former has exited.
*
* @param decisionMaker the DecisionMaker which has exited
*/
synchronized void decisionMakerExited(DecisionMaker decisionMaker)
{
if (this.decisionMaker == decisionMaker)
{
this.decisionMaker = null;
}
}
/**
* Retrieves a JSON representation of this instance for the purposes of the
* REST API of Videobridge.
*
* By the way, the method name reflects the fact that the method handles an
* HTTP GET request.
*
*
* @return a JSONObject which represents this instance of the
* purposes of the REST API of Videobridge
*/
@SuppressWarnings("unchecked")
public JSONObject doGetJSON()
{
JSONObject jsonObject;
if (DEBUG)
{
synchronized (this)
{
jsonObject = new JSONObject();
// dominantSpeaker
T dominantSpeaker = getDominantSpeaker();
jsonObject.put("dominantSpeaker", Objects.toString(dominantSpeaker));
// speakers
Collection> speakersCollection = this.speakers.values();
JSONArray speakersArray = new JSONArray();
for (Speaker speaker : speakersCollection)
{
JSONObject speakerJSONObject = new JSONObject();
// id
speakerJSONObject.put("id", speaker.id.toString());
// levels
speakerJSONObject.put("levels", speaker.getLevels());
speakersArray.add(speakerJSONObject);
}
jsonObject.put("speakers", speakersArray);
}
}
else
{
// Retrieving a JSON representation of a
// DominantSpeakerIdentification has been implemented for the
// purposes of debugging only.
jsonObject = null;
}
return jsonObject;
}
/**
* Gets the identifier of the dominant speaker.
*/
public T getDominantSpeaker()
{
return dominantId;
}
/**
* Gets the Speaker in this multipoint conference identified by a
* specific {@code id}. If no such Speaker exists, a new Speaker
* is initialized and returned.
*
* @param id the identifier of the Speaker to return.
* @return the Speaker in this multipoint conference identified by {@code id}.
*/
@NotNull
private synchronized Speaker getOrCreateSpeaker(T id)
{
Speaker speaker = speakers.get(id);
if (speaker == null)
{
speaker = new Speaker<>(id);
speakers.put(id, speaker);
// Since we've created a new Speaker in the multipoint conference,
// we'll very likely need to make a decision whether there have been
// speaker switch events soon.
maybeStartDecisionMaker();
}
return speaker;
}
/**
* Update loudest speaker list.
* @param speaker the speaker with a new energy level
* @param level the energy level
* @param now the current time
* @return The current ranking statistics.
*/
private synchronized SpeakerRanking updateLoudestList(Speaker speaker, int level, long now)
{
boolean isDominant = dominantId != null && dominantId.equals(speaker.id);
if (level < 0)
{
/* Ignore this level, it is too old. Just gather the stats. */
int rank = 0;
while (rank < loudest.size() && loudest.get(rank) != speaker)
++rank;
return new SpeakerRanking(isDominant, rank, speaker.energyScore);
}
/* exponential smoothing. round to nearest. */
speaker.energyScore = (energyAlphaPct * level + (100 - energyAlphaPct) * speaker.energyScore + 50) / 100;
if (numLoudestToTrack == 0)
return new SpeakerRanking(isDominant, 0, speaker.energyScore);
long oldestValid = now - energyExpireTimeMs;
logger.trace(() -> "Want to add " + speaker.id.toString()
+ " with score " + speaker.energyScore + ". Last level = " + level + ".");
int i = 0;
while (i < loudest.size())
{
Speaker cur = loudest.get(i);
if (cur.getLastLevelChangedTime() < oldestValid)
{
logger.trace(() -> "Removing " + cur.id.toString() + ". old.");
loudest.remove(i);
continue;
}
if (cur == speaker)
{
logger.trace(() -> "Removing " + cur.id.toString() + ". same.");
loudest.remove(i);
continue;
}
++i;
}
int rank = 0;
while (rank < loudest.size())
{
Speaker cur = loudest.get(rank);
if (cur.energyScore < speaker.energyScore)
break;
++rank;
}
if (rank < numLoudestToTrack)
{
final int pos = rank;
logger.trace(() -> "Adding " + speaker.id.toString() + " at position " + pos + ".");
loudest.add(rank, speaker);
if (loudest.size() > numLoudestToTrack)
loudest.remove(numLoudestToTrack);
}
if (logger.isTraceEnabled())
{
i = 0;
while (i < loudest.size())
{
Speaker cur = loudest.get(i);
logger.trace("New list: " + i + ": " + cur.id.toString() + ": " + cur.energyScore + ".");
++i;
}
}
return new SpeakerRanking(isDominant, rank, speaker.energyScore);
}
/**
* Query whether a particular endpoint is currently one of the loudest speakers.
*/
public synchronized boolean isAmongLoudest(T id)
{
return loudest.stream().anyMatch(speaker -> speaker.id.equals(id));
}
/**
* {@inheritDoc}
*/
@Override
public SpeakerRanking levelChanged(T id, int level)
{
Speaker speaker;
long now = clock.millis();
synchronized (this)
{
speaker = getOrCreateSpeaker(id);
// Note that this ActiveSpeakerDetector is still in use. When it is
// not in use long enough, its DecisionMaker i.e. background thread
// will prepare itself and, consequently, this
// DominantSpeakerIdentification for garbage collection.
if (lastLevelChangedTime < now)
{
lastLevelChangedTime = now;
// A report or measurement of an audio level indicates that this
// DominantSpeakerIdentification is in use and, consequently,
// that it'll very likely need to make a decision whether there
// have been speaker switch events soon.
maybeStartDecisionMaker();
}
}
int cookedLevel = speaker.levelChanged(level, now);
return updateLoudestList(speaker, cookedLevel, now);
}
/**
* Makes the decision whether there has been a speaker switch event. If
* there has been such an event, notifies the registered listeners that a
* new speaker is dominating the multipoint conference.
*/
private void makeDecision(long now)
{
// If we have to fire events to any registered listeners eventually, we
// will want to do it outside the synchronized block.
T oldDominantSpeakerValue = null, newDominantSpeakerValue = null;
synchronized (this)
{
int speakerCount = speakers.size();
T newDominantId;
if (speakerCount == 0)
{
// If there are no Speakers in a multipoint conference, then there are no speaker switch events to detect.
// We either have no dominant speaker, or we're in a silence period (if silence detection is enabled).
newDominantId = null;
}
else if (speakerCount == 1)
{
// If there is a single Speaker in a multipoint conference, then it is either the dominant speaker, or
// we're in a silence period (if silence detection is enabled).
Speaker speaker = speakers.values().iterator().next();
newDominantId = speaker.id;
if (enableSilence)
{
speaker.evaluateSpeechActivityScores(now);
long timeSinceNonSilence = now - speaker.lastNonSilence;
if (timeSinceNonSilence > timeoutToSilenceInterval)
{
newDominantId = null;
}
}
}
else
{
boolean inSilence = enableSilence && dominantId == null;
Speaker dominantSpeaker
= (dominantId == null)
? null
: speakers.get(dominantId);
// If there is no dominant speaker, nominate one at random and then
// let the other speakers compete with the nominated one.
if (dominantSpeaker == null)
{
Map.Entry> s = speakers.entrySet().iterator().next();
dominantSpeaker = s.getValue();
newDominantId = s.getKey();
}
else
{
newDominantId = dominantSpeaker.id;
}
// At this point dominantSpeaker==null iff inSilence==true.
if (dominantSpeaker != null)
{
dominantSpeaker.evaluateSpeechActivityScores(now);
}
double[] relativeSpeechActivities = this.relativeSpeechActivities;
// If multiple speakers cause speaker switches, they compete among
// themselves by their relative speech activities in the middle
// time-interval.
double newDominantC2 = C2;
for (Map.Entry> s : speakers.entrySet())
{
Speaker speaker = s.getValue();
// The dominant speaker does not compete with itself. In other
// words, there is no use detecting a speaker switch from the
// dominant speaker to the dominant speaker. Technically, the
// relative speech activities are all zeroes for the dominant
// speaker.
if (speaker == dominantSpeaker)
{
continue;
}
speaker.evaluateSpeechActivityScores(now);
// Compute the relative speech activities for the immediate,
// medium and long time-intervals.
for (int interval = 0;
interval < relativeSpeechActivities.length;
++interval)
{
// When in a silence period we use MIN_SPEECH_ACTIVITY_SCORE as the scores to compete against.
double dominantSpeakerScore = dominantSpeaker == null ? MIN_SPEECH_ACTIVITY_SCORE
: dominantSpeaker.getSpeechActivityScore(interval);
relativeSpeechActivities[interval]
= Math.log(speaker.getSpeechActivityScore(interval) / dominantSpeakerScore);
}
double c1 = relativeSpeechActivities[0];
double c2 = relativeSpeechActivities[1];
double c3 = relativeSpeechActivities[2];
if ((c1 > C1) && (c2 > C2) && (c3 > C3) && (c2 > newDominantC2))
{
// If multiple speakers cause speaker switches, they compete
// among themselves by their relative speech activities in
// the middle time-interval.
newDominantC2 = c2;
newDominantId = s.getKey();
}
}
if (enableSilence && dominantSpeaker != null && newDominantId == dominantSpeaker.id)
{
// We're not in a silence period, and none of the non-dominant speakers won the challenge. Check if
// the current dominant speaker has been silent for the timeout period, and if so switch to "silence"
// mode.
long timeSinceNonSilence = now - dominantSpeaker.lastNonSilence;
if (timeSinceNonSilence > timeoutToSilenceInterval)
{
newDominantId = null;
}
}
}
if ((newDominantId != null || enableSilence) && !Objects.equals(newDominantId, dominantId))
{
oldDominantSpeakerValue = dominantId;
dominantId = newDominantId;
newDominantSpeakerValue = dominantId;
}
} // synchronized (this)
// Now that we are outside the synchronized block, fire events, if any,
// to any registered listeners.
if ((newDominantSpeakerValue != null || enableSilence) &&
!Objects.equals(newDominantSpeakerValue, oldDominantSpeakerValue))
{
fireActiveSpeakerChanged(newDominantSpeakerValue);
}
}
/**
* Starts a background thread which is to repeatedly make the (global)
* decision about speaker switches if such a background thread has not been
* started yet and if the current state of this
* DominantSpeakerIdentification justifies the start of such a
* background thread (e.g. there is at least one Speaker in this
* multipoint conference).
*/
private synchronized void maybeStartDecisionMaker()
{
if ((this.decisionMaker == null) && !speakers.isEmpty())
{
DecisionMaker decisionMaker = new DecisionMaker(this);
boolean scheduled = false;
this.decisionMaker = decisionMaker;
try
{
executor.execute(decisionMaker);
scheduled = true;
}
finally
{
if (!scheduled && (this.decisionMaker == decisionMaker))
{
this.decisionMaker = null;
}
}
}
}
/**
* Runs in the background/daemon Thread of {@link #decisionMaker}
* and makes the decision whether there has been a speaker switch event.
*
* @return a negative integer if the DecisionMaker is to exit or
* a non-negative integer to specify the time in milliseconds until the next
* execution of the DecisionMaker
*/
private long runInDecisionMaker()
{
long now = clock.millis();
long levelIdleTimeout = LEVEL_IDLE_TIMEOUT - (now - lastLevelIdleTime);
long sleep = 0;
if (levelIdleTimeout <= 0)
{
if (lastLevelIdleTime != 0)
{
timeoutIdleLevels(now);
}
lastLevelIdleTime = now;
}
else
{
sleep = levelIdleTimeout;
}
long decisionTimeout = DECISION_INTERVAL - (now - lastDecisionTime);
if (decisionTimeout <= 0)
{
// The identification of the dominant active speaker may be a
// time-consuming ordeal so the time of the last decision is the
// time of the beginning of a decision iteration.
lastDecisionTime = now;
makeDecision(now);
// The identification of the dominant active speaker may be a
// time-consuming ordeal so the timeout to the next decision
// iteration should be computed after the end of the decision
// iteration.
decisionTimeout = DECISION_INTERVAL - (clock.millis() - now);
}
if ((decisionTimeout > 0) && (sleep > decisionTimeout))
{
sleep = decisionTimeout;
}
return sleep;
}
/**
* Runs in the background/daemon Thread of a specific
* DecisionMaker and makes the decision whether there has been a
* speaker switch event.
*
* @param decisionMaker the DecisionMaker invoking the method
* @return a negative integer if the decisionMaker is to exit or
* a non-negative integer to specify the time in milliseconds until the next
* execution of the decisionMaker
*/
long runInDecisionMaker(DecisionMaker decisionMaker)
{
synchronized (this)
{
// Most obviously, DecisionMakers no longer employed by this
// DominantSpeakerIdentification should cease to exist as soon as
// possible.
if (this.decisionMaker != decisionMaker)
{
return -1;
}
// If the decisionMaker has been unnecessarily executing long
// enough, kill it in order to have a more deterministic behavior
// with respect to disposal.
if (0 < lastDecisionTime)
{
long idle = lastDecisionTime - lastLevelChangedTime;
if (idle >= DECISION_MAKER_IDLE_TIMEOUT)
{
return -1;
}
}
}
return runInDecisionMaker();
}
/**
* Notifies the Speakers in this multipoint conference who have not
* received or measured audio levels for a certain time (i.e.
* {@link #LEVEL_IDLE_TIMEOUT}) that they will very likely not have a level
* within a certain time-frame of the DominantSpeakerIdentification
* algorithm. Additionally, removes the non-dominant Speakers who
* have not received or measured audio levels for far too long (i.e.
* {@link #SPEAKER_IDLE_TIMEOUT}).
*
* @param now the time at which the timing out is being detected
*/
private synchronized void timeoutIdleLevels(long now)
{
Iterator>> i = speakers.entrySet().iterator();
while (i.hasNext())
{
Speaker speaker = i.next().getValue();
long idle = now - speaker.getLastLevelChangedTime();
// Remove a non-dominant Speaker if he/she has been idle for far too
// long.
if ((SPEAKER_IDLE_TIMEOUT < idle) && ((dominantId == null) || (speaker.id != dominantId)))
{
i.remove();
}
else if (LEVEL_IDLE_TIMEOUT < idle)
{
speaker.levelTimedOut();
}
}
}
/**
* Represents the background thread which repeatedly makes the (global)
* decision about speaker switches. Weakly references an associated
* DominantSpeakerIdentification instance in order to eventually
* detect that the multipoint conference has actually expired and that the
* background Thread should perish.
*
* @author Lyubomir Marinov
*/
private static class DecisionMaker
implements Runnable
{
/**
* The DominantSpeakerIdentification instance which is
* repeatedly run into this background thread in order to make the
* (global) decision about speaker switches. It is a
* WeakReference in order to eventually detect that the
* mulipoint conference has actually expired and that this background
* Thread should perish.
*/
private final WeakReference> algorithm;
/**
* Initializes a new DecisionMaker instance which is to
* repeatedly run a specific DominantSpeakerIdentification
* into a background thread in order to make the (global) decision about
* speaker switches.
*
* @param algorithm the DominantSpeakerIdentification to be
* repeatedly run by the new instance in order to make the (global)
* decision about speaker switches
*/
public DecisionMaker(DominantSpeakerIdentification algorithm)
{
this.algorithm = new WeakReference<>(algorithm);
}
/**
* Repeatedly runs {@link #algorithm} i.e. makes the (global) decision
* about speaker switches until the multipoint conference expires.
*/
@Override
public void run()
{
boolean exit = false;
DominantSpeakerIdentification algorithm = this.algorithm.get();
if (algorithm == null)
{
exit = true;
}
else
{
long sleep;
try
{
sleep = algorithm.runInDecisionMaker(this);
}
catch (Exception e)
{
// If an exception occurs we do not re-schedule.
sleep = -1;
}
// A negative sleep value is contracted to mean that this DecisionMaker should not re-schedule itself.
if (sleep < 0)
{
exit = true;
}
else
{
algorithm.executor.schedule(this, sleep, TimeUnit.MILLISECONDS);
}
}
if (exit)
{
// Notify the algorithm that this DecisionMaker will no longer run. Subsequently, the algorithm may
// decide to create and schedule another one if and when it's needed.
algorithm = this.algorithm.get();
if (algorithm != null)
{
algorithm.decisionMakerExited(this);
}
}
}
}
/**
* Represents a speaker in a multipoint conference identified by an ID.
*
* @author Lyubomir Marinov
*/
private class Speaker
{
private final byte[] immediates = new byte[LONG_COUNT * N3 * N2];
/**
* The last {@link #clock} time in millis at which this speaker was not silent. We consider it being silent if
* {@link #longSpeechActivityScore} == {@link #MIN_SPEECH_ACTIVITY_SCORE} to allow short bursts of activity
* to not interrupt a silence period.
*/
private long lastNonSilence = -1;
/**
* The speech activity score of this Speaker for the immediate
* time-interval.
*/
private double immediateSpeechActivityScore = MIN_SPEECH_ACTIVITY_SCORE;
/**
* The time in milliseconds of the most recent invocation of
* {@link #levelChanged(int,long)} i.e. the last time at which an actual
* (audio) level was reported or measured for this Speaker. If
* no level is reported or measured for this Speaker long
* enough i.e. {@link #LEVEL_IDLE_TIMEOUT}, the associated
* DominantSpeakerIdentification will presume that this
* Speaker was muted for the duration of a certain frame.
*/
private long lastLevelChangedTime = clock.millis();
/**
* The (history of) audio levels received or measured for this
* Speaker.
*/
private final byte[] levels;
private final byte[] longs = new byte[LONG_COUNT];
/**
* The speech activity score of this Speaker for the long
* time-interval.
*/
private double longSpeechActivityScore = MIN_SPEECH_ACTIVITY_SCORE;
private final byte[] mediums = new byte[LONG_COUNT * N3];
/**
* The speech activity score of this Speaker for the medium
* time-interval.
*/
private double mediumSpeechActivityScore = MIN_SPEECH_ACTIVITY_SCORE;
/**
* The minimum (audio) level received or measured for this
* Speaker. Since MIN_LEVEL is specified for samples
* generated by a muted audio source, a value equal to
* MIN_LEVEL indicates that the minimum level for this
* Speaker has not been determined yet.
*/
private byte minLevel = MIN_LEVEL;
/**
* The (current) estimate of the minimum (audio) level received or
* measured for this Speaker. Used to increase the value of
* {@link #minLevel}
*/
private byte nextMinLevel = MIN_LEVEL;
/**
* The number of subsequent (audio) levels received or measured for this
* Speaker which have been monitored thus far in order to
* estimate an up-to-date minimum (audio) level received or measured for
* this Speaker.
*/
private int nextMinLevelWindowLength;
/** Exponential smoothing of filtered energy values.
* Synchronized by parent class.
*/
int energyScore;
/**
* The identifier of this Speaker which is unique within this {@link DominantSpeakerIdentification}.
*/
public final U id;
/**
* Initializes a new Speaker instance with a specific identifier
*
* @param id the object identifying this speaker.
* instance
*/
public Speaker(U id)
{
this.id = id;
levels = new byte[immediates.length];
}
private boolean computeImmediates()
{
// The minimum audio level received or measured for this Speaker is
// the level of "silence" for this Speaker. Since the various
// Speakers may differ in their levels of "silence", put all
// Speakers on equal footing by replacing the individual levels of
// "silence" with the uniform level of absolute silence.
byte[] immediates = this.immediates;
byte[] levels = this.levels;
byte minLevel = (byte) (this.minLevel + N1_SUBUNIT_LENGTH);
boolean changed = false;
for (int i = 0; i < immediates.length; ++i)
{
byte level = levels[i];
if (level < minLevel)
level = MIN_LEVEL;
byte immediate = (byte) (level / N1_SUBUNIT_LENGTH);
if (immediates[i] != immediate)
{
immediates[i] = immediate;
changed = true;
}
}
return changed;
}
private boolean computeLongs()
{
return computeBigs(mediums, longs, LONG_THRESHOLD);
}
private boolean computeMediums()
{
return computeBigs(immediates, mediums, MEDIUM_THRESHOLD);
}
/**
* Computes/evaluates the speech activity score of this Speaker
* for the immediate time-interval.
*/
private void evaluateImmediateSpeechActivityScore()
{
immediateSpeechActivityScore = computeSpeechActivityScore(immediates[0], N1, 0.78);
}
/**
* Computes/evaluates the speech activity score of this Speaker
* for the long time-interval.
*/
private void evaluateLongSpeechActivityScore(long now)
{
longSpeechActivityScore = computeSpeechActivityScore(longs[0], N3, 47);
if (longSpeechActivityScore > MIN_SPEECH_ACTIVITY_SCORE)
{
lastNonSilence = now;
}
}
/**
* Computes/evaluates the speech activity score of this Speaker
* for the medium time-interval.
*/
private void evaluateMediumSpeechActivityScore()
{
mediumSpeechActivityScore = computeSpeechActivityScore(mediums[0], N2, 24);
}
/**
* Evaluates the speech activity scores of this Speaker for the
* immediate, medium, and long time-intervals. Invoked when it is time
* to decide whether there has been a speaker switch event.
*/
synchronized void evaluateSpeechActivityScores(long now)
{
if (computeImmediates())
{
evaluateImmediateSpeechActivityScore();
if (computeMediums())
{
evaluateMediumSpeechActivityScore();
if (computeLongs())
{
evaluateLongSpeechActivityScore(now);
}
}
}
}
/**
* Gets the time in milliseconds at which an actual (audio) level was
* reported or measured for this Speaker last.
*
* @return the time in milliseconds at which an actual (audio) level
* was reported or measured for this Speaker last
*/
public synchronized long getLastLevelChangedTime()
{
return lastLevelChangedTime;
}
/**
* Gets the (history of) audio levels received or measured for this
* Speaker.
*
* @return a String that lists the (history of) audio
* levels received or measured for this Speaker
*/
String getLevels()
{
// The levels of Speaker are internally maintained starting with the
// last audio level received or measured for this Speaker and ending
// with the first audio level received or measured for this Speaker.
// Reverse the list and print them in the order they were received.
byte[] src = this.levels;
StringBuilder sb = new StringBuilder();
sb.append('[');
for (int s = src.length - 1; s >= 0; --s)
{
sb.append(src[s]);
sb.append(',');
}
sb.setCharAt(sb.length() - 1, ']'); /* replace last comma */
return sb.toString();
}
/**
* Gets the speech activity score of this Speaker for a
* specific time-interval.
*
* @param interval 0 for the immediate time-interval,
* 1 for the medium time-interval, or 2 for the long
* time-interval
* @return the speech activity score of this Speaker for the
* time-interval specified by index
*/
double getSpeechActivityScore(int interval)
{
switch (interval)
{
case 0:
return immediateSpeechActivityScore;
case 1:
return mediumSpeechActivityScore;
case 2:
return longSpeechActivityScore;
default:
throw new IllegalArgumentException("interval " + interval);
}
}
/**
* Notifies this Speaker that a new audio level has been
* received or measured at a specific time.
*
* @param level the audio level which has been received or measured for
* this Speaker
* @param time the (local System) time in milliseconds at which
* the specified level has been received or measured
* @return the audio level that was applied, after any filtering or
* level adjustment has taken place. If negative, the audio level
* was ignored.
*/
public synchronized int levelChanged(int level, long time)
{
// It sounds relatively reasonable that late audio levels should
// better be discarded.
if (lastLevelChangedTime <= time)
{
lastLevelChangedTime = time;
// Ensure that the specified level is within the supported
// range.
byte b;
if (level < MIN_LEVEL)
b = MIN_LEVEL;
else if (level > MAX_LEVEL)
b = MAX_LEVEL;
else
b = (byte) level;
// Push the specified level into the history of audio levels
// received or measured for this Speaker.
System.arraycopy(levels, 0, levels, 1, levels.length - 1);
levels[0] = b;
// Determine the minimum level received or measured for this
// Speaker.
updateMinLevel(b);
return b >= (minLevel + N1_SUBUNIT_LENGTH) ? b : 0;
}
else
{
return -1;
}
}
/**
* Notifies this Speaker that no new audio level has been
* received or measured for a certain time which very likely means that
* this Speaker will not have a level within a certain
* time-frame of a DominantSpeakerIdentification algorithm.
*/
public synchronized void levelTimedOut()
{
levelChanged(MIN_LEVEL, lastLevelChangedTime);
}
/**
* Updates the minimum (audio) level received or measured for this
* Speaker in light of the receipt of a specific level.
*
* @param level the audio level received or measured for this
* Speaker
*/
private void updateMinLevel(byte level)
{
if (level != MIN_LEVEL)
{
if ((minLevel == MIN_LEVEL) || (minLevel > level))
{
minLevel = level;
nextMinLevel = MIN_LEVEL;
nextMinLevelWindowLength = 0;
}
else
{
// The specified (audio) level is greater than the minimum
// level received or measure for this Speaker. However, the
// minimum level may be out-of-date by now. Estimate an
// up-to-date minimum level and, eventually, make it the
// minimum level received or measured for this Speaker.
if (nextMinLevel == MIN_LEVEL)
{
nextMinLevel = level;
nextMinLevelWindowLength = 1;
}
else
{
if (nextMinLevel > level)
{
nextMinLevel = level;
}
nextMinLevelWindowLength++;
if (nextMinLevelWindowLength >= MIN_LEVEL_WINDOW_LENGTH)
{
// The arithmetic mean will increase the minimum
// level faster than the geometric mean. Since the
// goal is to track a minimum, it sounds reasonable
// to go with a slow increase.
double newMinLevel
= Math.sqrt(minLevel * (double) nextMinLevel);
// Ensure that the new minimum level is within the
// supported range.
if (newMinLevel < MIN_LEVEL)
newMinLevel = MIN_LEVEL;
else if (newMinLevel > MAX_LEVEL)
newMinLevel = MAX_LEVEL;
minLevel = (byte) newMinLevel;
nextMinLevel = MIN_LEVEL;
nextMinLevelWindowLength = 0;
}
}
}
}
}
}
}