Exemplo n.º 1
0
void DlgTrackInfo::populateFields(TrackPointer pTrack) {
    setWindowTitle(pTrack->getTitle());

    // Editable fields
    txtTrackName->setText(pTrack->getTitle());
    txtArtist->setText(pTrack->getArtist());
    txtAlbum->setText(pTrack->getAlbum());
    txtAlbumArtist->setText(pTrack->getAlbumArtist());
    txtGenre->setText(pTrack->getGenre());
    txtComposer->setText(pTrack->getComposer());
    txtGrouping->setText(pTrack->getGrouping());
    txtYear->setText(pTrack->getYear());
    txtTrackNumber->setText(pTrack->getTrackNumber());
    txtComment->setText(pTrack->getComment());
    spinBpm->setValue(pTrack->getBpm());
    // Non-editable fields
    txtDuration->setText(pTrack->getDurationStr());
    txtFilepath->setText(pTrack->getFilename());
    txtLocation->setText(pTrack->getLocation());
    txtType->setText(pTrack->getType());
    txtBitrate->setText(QString(pTrack->getBitrateStr()) + (" ") + tr("kbps"));
    txtBpm->setText(pTrack->getBpmStr());
    txtKey->setText(pTrack->getKeyText());
    BeatsPointer pBeats = pTrack->getBeats();
    bool beatsSupportsSet = !pBeats || (pBeats->getCapabilities() & Beats::BEATSCAP_SET);
    bool enableBpmEditing = !pTrack->hasBpmLock() && beatsSupportsSet;
    spinBpm->setEnabled(enableBpmEditing);
    bpmTap->setEnabled(enableBpmEditing);
    bpmDouble->setEnabled(enableBpmEditing);
    bpmHalve->setEnabled(enableBpmEditing);
    bpmTwoThirds->setEnabled(enableBpmEditing);
    bpmThreeFourth->setEnabled(enableBpmEditing);
}
Exemplo n.º 2
0
void BpmControl::slotAdjustBeatsSlower(double v) {
    BeatsPointer pBeats = m_pBeats;
    if (v > 0 && pBeats && (pBeats->getCapabilities() & Beats::BEATSCAP_SETBPM)) {
        double new_bpm = math_max(10.0, pBeats->getBpm() - .01);
        pBeats->setBpm(new_bpm);
    }
}
Exemplo n.º 3
0
void BpmControl::slotTranslateBeatsEarlier(double v) {
    BeatsPointer pBeats = m_pBeats;
    if (v > 0 && pBeats &&
            (pBeats->getCapabilities() & Beats::BEATSCAP_TRANSLATE)) {
        const int translate_dist = getSampleOfTrack().rate * -.01;
        pBeats->translate(translate_dist);
    }
}
Exemplo n.º 4
0
void BpmControl::slotTranslateBeatsLater(double v) {
    BeatsPointer pBeats = m_pBeats;
    if (v > 0 && pBeats &&
            (pBeats->getCapabilities() & Beats::BEATSCAP_TRANSLATE)) {
        // TODO(rryan): Track::getSampleRate is possibly inaccurate!
        const int translate_dist = getSampleOfTrack().rate * .01;
        pBeats->translate(translate_dist);
    }
}
Exemplo n.º 5
0
void BpmControl::slotBeatsTranslateMatchAlignment(double v) {
    BeatsPointer pBeats = m_pBeats;
    if (v > 0 && pBeats && (pBeats->getCapabilities() & Beats::BEATSCAP_TRANSLATE)) {
        // Must reset the user offset *before* calling getPhaseOffset(),
        // otherwise it will always return 0 if master sync is active.
        m_dUserOffset.setValue(0.0);

        double offset = getPhaseOffset(getSampleOfTrack().current);
        pBeats->translate(-offset);
    }
}
Exemplo n.º 6
0
void BpmControl::slotBeatsTranslate(double v) {
    BeatsPointer pBeats = m_pBeats;
    if (v > 0 && pBeats && (pBeats->getCapabilities() & Beats::BEATSCAP_TRANSLATE)) {
        double currentSample = getSampleOfTrack().current;
        double closestBeat = pBeats->findClosestBeat(currentSample);
        int delta = currentSample - closestBeat;
        if (delta % 2 != 0) {
            delta--;
        }
        pBeats->translate(delta);
    }
}
Exemplo n.º 7
0
// static
bool BpmControl::getBeatContext(const BeatsPointer& pBeats,
                                const double dPosition,
                                double* dpPrevBeat,
                                double* dpNextBeat,
                                double* dpBeatLength,
                                double* dpBeatPercentage) {
    if (!pBeats) {
        return false;
    }

    double dPrevBeat;
    double dNextBeat;
    if (!pBeats->findPrevNextBeats(dPosition, &dPrevBeat, &dNextBeat)) {
        return false;
    }

    if (dpPrevBeat != NULL) {
        *dpPrevBeat = dPrevBeat;
    }

    if (dpNextBeat != NULL) {
        *dpNextBeat = dNextBeat;
    }

    return getBeatContextNoLookup(dPosition, dPrevBeat, dNextBeat,
                                  dpBeatLength, dpBeatPercentage);
}
Exemplo n.º 8
0
double BpmControl::updateLocalBpm() {
    double prev_local_bpm = m_pLocalBpm->get();
    double local_bpm = 0;
    BeatsPointer pBeats = m_pBeats;
    if (pBeats) {
        local_bpm = pBeats->getBpmAroundPosition(
                getSampleOfTrack().current, kLocalBpmSpan);
        if (local_bpm == -1) {
            local_bpm = m_pFileBpm->get();
        }
    } else {
        local_bpm = m_pFileBpm->get();
    }
    if (local_bpm != prev_local_bpm) {
        m_pLocalBpm->set(local_bpm);
        slotUpdateEngineBpm();
    }
    return local_bpm;
}
Exemplo n.º 9
0
void BpmControl::slotTapFilter(double averageLength, int numSamples) {
    // averageLength is the average interval in milliseconds tapped over
    // numSamples samples.  Have to convert to BPM now:

    if (averageLength <= 0)
        return;

    if (numSamples < 4)
        return;

    BeatsPointer pBeats = m_pBeats;
    if (!pBeats)
        return;

    // (60 seconds per minute) * (1000 milliseconds per second) / (X millis per
    // beat) = Y beats/minute
    double averageBpm = 60.0 * 1000.0 / averageLength / calcRateRatio();
    pBeats->setBpm(averageBpm);
}
Exemplo n.º 10
0
void BpmControl::slotFileBpmChanged(double file_bpm) {
    // Adjust the file-bpm with the current setting of the rate to get the
    // engine BPM. We only do this for SYNC_NONE decks because EngineSync will
    // set our BPM if the file BPM changes. See SyncControl::fileBpmChanged().
    //qDebug() << "BpmControl::slotFileBpmChanged" << file_bpm;
    BeatsPointer pBeats = m_pBeats;
    if (pBeats) {
        const double beats_bpm =
                pBeats->getBpmAroundPosition(
                        getSampleOfTrack().current, kLocalBpmSpan);
        if (beats_bpm != -1) {
            m_pLocalBpm->set(beats_bpm);
        } else {
            m_pLocalBpm->set(file_bpm);
        }
    } else {
        m_pLocalBpm->set(file_bpm);
    }
    resetSyncAdjustment();
}
Exemplo n.º 11
0
double BpmControl::getNearestPositionInPhase(
        double dThisPosition, bool respectLoops, bool playing) {
    // Without a beatgrid, we don't know the phase offset.
    BeatsPointer pBeats = m_pBeats;
    if (!pBeats) {
        return dThisPosition;
    }

    SyncMode syncMode = getSyncMode();

    // Master buffer is always in sync!
    if (syncMode == SYNC_MASTER) {
        return dThisPosition;
    }

    // Get the current position of this deck.
    double dThisPrevBeat = m_pPrevBeat->get();
    double dThisNextBeat = m_pNextBeat->get();
    double dThisBeatLength;
    if (dThisPosition > dThisNextBeat || dThisPosition < dThisPrevBeat) {
        // There's a chance the COs might be out of date, so do a lookup.
        // TODO: figure out a way so that quantized control can take care of
        // this so this call isn't necessary.
        if (!getBeatContext(pBeats, dThisPosition,
                            &dThisPrevBeat, &dThisNextBeat,
                            &dThisBeatLength, NULL)) {
            return dThisPosition;
        }
    } else {
        if (!getBeatContextNoLookup(dThisPosition,
                                    dThisPrevBeat, dThisNextBeat,
                                    &dThisBeatLength, NULL)) {
            return dThisPosition;
        }
    }

    double dOtherBeatFraction;
    if (syncMode == SYNC_FOLLOWER) {
        // If we're a follower, it's easy to get the other beat fraction
        dOtherBeatFraction = m_dSyncTargetBeatDistance.getValue();
    } else {
        // If not, we have to figure it out
        EngineBuffer* pOtherEngineBuffer = pickSyncTarget();
        if (playing) {
            if (!pOtherEngineBuffer || pOtherEngineBuffer->getSpeed() == 0.0) {
                // "this" track is playing, or just starting
                // only match phase if the sync target is playing as well
                // else use the previouse phase of "this" track before the seek
                pOtherEngineBuffer = getEngineBuffer();
            }
        }

        if (!pOtherEngineBuffer) {
            // no suitable sync buffer found
            return dThisPosition;
        }

        TrackPointer otherTrack = pOtherEngineBuffer->getLoadedTrack();
        BeatsPointer otherBeats = otherTrack ? otherTrack->getBeats() : BeatsPointer();

        // If either track does not have beats, then we can't adjust the phase.
        if (!otherBeats) {
            return dThisPosition;
        }

        double dOtherLength = ControlObject::getControl(
                ConfigKey(pOtherEngineBuffer->getGroup(), "track_samples"))->get();
        double dOtherEnginePlayPos = pOtherEngineBuffer->getVisualPlayPos();
        double dOtherPosition = dOtherLength * dOtherEnginePlayPos;

        if (!BpmControl::getBeatContext(otherBeats, dOtherPosition,
                                        NULL, NULL, NULL, &dOtherBeatFraction)) {
            return dThisPosition;
        }
    }

    bool this_near_next = dThisNextBeat - dThisPosition <= dThisPosition - dThisPrevBeat;
    bool other_near_next = dOtherBeatFraction >= 0.5;

    // We want our beat fraction to be identical to theirs.

    // If the two tracks have similar alignment, adjust phase is straight-
    // forward.  Use the same fraction for both beats, starting from the previous
    // beat.  But if This track is nearer to the next beat and the Other track
    // is nearer to the previous beat, use This Next beat as the starting point
    // for the phase. (ie, we pushed the sync button late).  If This track
    // is nearer to the previous beat, but the Other track is nearer to the
    // next beat, we pushed the sync button early so use the double-previous
    // beat as the basis for the adjustment.
    //
    // This makes way more sense when you're actually mixing.
    //
    // TODO(XXX) Revisit this logic once we move away from tempo-locked,
    // infinite beatgrids because the assumption that findNthBeat(-2) always
    // works will be wrong then.

    double dNewPlaypos = (dOtherBeatFraction + m_dUserOffset.getValue()) * dThisBeatLength;
    if (this_near_next == other_near_next) {
        dNewPlaypos += dThisPrevBeat;
    } else if (this_near_next && !other_near_next) {
        dNewPlaypos += dThisNextBeat;
    } else {  //!this_near_next && other_near_next
        dThisPrevBeat = pBeats->findNthBeat(dThisPosition, -2);
        dNewPlaypos += dThisPrevBeat;
    }

    if (respectLoops) {
        // We might be seeking outside the loop.
        const bool loop_enabled = m_pLoopEnabled->toBool();
        const double loop_start_position = m_pLoopStartPosition->get();
        const double loop_end_position = m_pLoopEndPosition->get();

        // Cases for sanity:
        //
        // CASE 1
        // Two identical 1-beat loops, out of phase by X samples.
        // Other deck is at its loop start.
        // This deck is half way through. We want to jump forward X samples to the loop end point.
        //
        // Two identical 1-beat loop, out of phase by X samples.
        // Other deck is

        // If sync target is 50% through the beat,
        // If we are at the loop end point and hit sync, jump forward X samples.


        // TODO(rryan): Revise this with something that keeps a broader number of
        // cases in sync. This at least prevents breaking out of the loop.
        if (loop_enabled &&
                dThisPosition <= loop_end_position) {
            const double loop_length = loop_end_position - loop_start_position;
            const double end_delta = dNewPlaypos - loop_end_position;

            // Syncing to after the loop end.
            if (end_delta > 0 && loop_length > 0.0) {
                int i = end_delta / loop_length;
                dNewPlaypos = loop_start_position + end_delta - i * loop_length;

                // Move new position after loop jump into phase as well.
                // This is a recursive call, called only twice because of
                // respectLoops = false
                dNewPlaypos = getNearestPositionInPhase(dNewPlaypos, false, playing);
            }

            // Note: Syncing to before the loop beginning is allowed, because
            // loops are catching
        }
    }

    return dNewPlaypos;
}
Exemplo n.º 12
0
// TODO(XXX): Get rid of the horrible duplication here between initialise and
// loadStored.
bool AnalyserBeats::initialise(TrackPointer tio, int sampleRate, int totalSamples) {
    if (totalSamples == 0) {
        return false;
    }

    bool bPreferencesBeatDetectionEnabled = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_DETECTION_ENABLED)).toInt());
    if (!bPreferencesBeatDetectionEnabled) {
        qDebug() << "Beat calculation is deactivated";
        return false;
    }

    bool bpmLock = tio->hasBpmLock();
    if (bpmLock) {
        qDebug() << "Track is BpmLocked: Beat calculation will not start";
        return false;
    }

    bool allow_above = static_cast<bool>(m_pConfig->getValueString(
        ConfigKey(BPM_CONFIG_KEY, BPM_ABOVE_RANGE_ENABLED)).toInt());
    if (allow_above) {
        m_iMinBpm = 0;
        m_iMaxBpm = 9999;
    } else {
        m_iMinBpm = m_pConfig->getValueString(ConfigKey(BPM_CONFIG_KEY, BPM_RANGE_START)).toInt();
        m_iMaxBpm = m_pConfig->getValueString(ConfigKey(BPM_CONFIG_KEY, BPM_RANGE_END)).toInt();
    }

    m_bPreferencesFixedTempo = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_FIXED_TEMPO_ASSUMPTION)).toInt());
    m_bPreferencesOffsetCorrection = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_FIXED_TEMPO_OFFSET_CORRECTION)).toInt());
    m_bPreferencesReanalyzeOldBpm = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_REANALYZE_WHEN_SETTINGS_CHANGE)).toInt());
    m_bPreferencesFastAnalysis = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_FAST_ANALYSIS_ENABLED)).toInt());


    QString library = m_pConfig->getValueString(
        ConfigKey(VAMP_CONFIG_KEY, VAMP_ANALYSER_BEAT_LIBRARY));
    QString pluginID = m_pConfig->getValueString(
        ConfigKey(VAMP_CONFIG_KEY, VAMP_ANALYSER_BEAT_PLUGIN_ID));

    m_pluginId = pluginID;
    m_iSampleRate = sampleRate;
    m_iTotalSamples = totalSamples;

    // If the track already has a Beats object then we need to decide whether to
    // analyze this track or not.
    bool bShouldAnalyze = false;
    BeatsPointer pBeats = tio->getBeats();
    if (pBeats) {
        QString version = pBeats->getVersion();
        QString subVersion = pBeats->getSubVersion();

        QHash<QString, QString> extraVersionInfo = getExtraVersionInfo(
            m_pluginId, m_bPreferencesFastAnalysis);
        QString newVersion = BeatFactory::getPreferredVersion(
                m_bPreferencesFixedTempo);
        QString newSubVersion = BeatFactory::getPreferredSubVersion(
                m_bPreferencesFixedTempo, m_bPreferencesOffsetCorrection,
                m_iMinBpm, m_iMaxBpm, extraVersionInfo);

        if (version == newVersion && subVersion == newSubVersion) {
            // If the version and settings have not changed then if the world is
            // sane, re-analyzing will do nothing.
            bShouldAnalyze = false;
            qDebug() << "Beat sub-version has not changed since previous analysis so not analyzing.";
        } else if (m_bPreferencesReanalyzeOldBpm) {
            bShouldAnalyze = true;
        } else if (pBeats->getBpm() == 0.0) {
            bShouldAnalyze = true;
            qDebug() << "BPM is 0 for track so re-analyzing despite preference settings.";
        } else if (pBeats->findNextBeat(0) <= 0.0) {
            bShouldAnalyze = true;
            qDebug() << "First beat is 0 for grid so analyzing track to find first beat.";
        } else {
            bShouldAnalyze = false;
            qDebug() << "Beat calculation skips analyzing because the track has"
                     << "a BPM computed by a previous Mixxx version and user"
                     << "preferences indicate we should not change it.";
        }
    } else {
        // No valid keys stored so we want to analyze this track.
        bShouldAnalyze = true;
    }

    if (bShouldAnalyze) {
        m_pVamp = new VampAnalyser(m_pConfig);
        bShouldAnalyze = m_pVamp->Init(library, pluginID, m_iSampleRate, totalSamples,
                                       m_bPreferencesFastAnalysis);
        if (!bShouldAnalyze) {
            delete m_pVamp;
            m_pVamp = NULL;
        }
    }

    if (bShouldAnalyze) {
        qDebug() << "Beat calculation started with plugin" << pluginID;
    } else {
        qDebug() << "Beat calculation will not start";
    }

    return bShouldAnalyze;
}
Exemplo n.º 13
0
void AnalyserBeats::finalise(TrackPointer tio) {
    if (m_pVamp == NULL) {
        return;
    }

    // Call End() here, because the number of total samples may have been
    // estimated incorrectly.
    bool success = m_pVamp->End();
    qDebug() << "Beat Calculation" << (success ? "complete" : "failed");

    QVector<double> beats = m_pVamp->GetInitFramesVector();
    delete m_pVamp;
    m_pVamp = NULL;

    if (beats.isEmpty()) {
        qDebug() << "Could not detect beat positions from Vamp.";
        return;
    }

    QHash<QString, QString> extraVersionInfo = getExtraVersionInfo(
        m_pluginId, m_bPreferencesFastAnalysis);
    BeatsPointer pBeats = BeatFactory::makePreferredBeats(
        tio, beats, extraVersionInfo,
        m_bPreferencesFixedTempo, m_bPreferencesOffsetCorrection,
        m_iSampleRate, m_iTotalSamples,
        m_iMinBpm, m_iMaxBpm);

    BeatsPointer pCurrentBeats = tio->getBeats();

    // If the track has no beats object then set our newly generated one
    // regardless of beat lock.
    if (!pCurrentBeats) {
        tio->setBeats(pBeats);
        return;
    }

    // If the track received the beat lock while we were analyzing it then we
    // abort setting it.
    if (tio->hasBpmLock()) {
        qDebug() << "Track was BPM-locked as we were analysing it. Aborting analysis.";
        return;
    }

    // If the user prefers to replace old beatgrids with newly generated ones or
    // the old beatgrid has 0-bpm then we replace it.
    bool zeroCurrentBpm = pCurrentBeats->getBpm() == 0.0f;
    if (m_bPreferencesReanalyzeOldBpm || zeroCurrentBpm) {
        if (zeroCurrentBpm) {
            qDebug() << "Replacing 0-BPM beatgrid with a" << pBeats->getBpm()
                     << "beatgrid.";
        }
        tio->setBeats(pBeats);
        return;
    }

    // If we got here then the user doesn't want to replace the beatgrid but
    // since the first beat is zero we'll apply the offset we just detected.
    double currentFirstBeat = pCurrentBeats->findNextBeat(0);
    double newFirstBeat = pBeats->findNextBeat(0);
    if (currentFirstBeat == 0.0 && newFirstBeat > 0) {
        pCurrentBeats->translate(newFirstBeat);
    }
}
Exemplo n.º 14
0
// TODO(XXX): Get rid of the horrible duplication here between initialise and
// loadStored.
bool AnalyserBeats::loadStored(TrackPointer tio) const {
    int iMinBpm;
    int iMaxBpm;

    bool allow_above = static_cast<bool>(m_pConfig->getValueString(
        ConfigKey(BPM_CONFIG_KEY, BPM_ABOVE_RANGE_ENABLED)).toInt());
    if (allow_above) {
        iMinBpm = 0;
        iMaxBpm = 9999;
    } else {
        iMinBpm = m_pConfig->getValueString(ConfigKey(BPM_CONFIG_KEY, BPM_RANGE_START)).toInt();
        iMaxBpm = m_pConfig->getValueString(ConfigKey(BPM_CONFIG_KEY, BPM_RANGE_END)).toInt();
    }

    bool bPreferencesFixedTempo = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_FIXED_TEMPO_ASSUMPTION)).toInt());
    bool bPreferencesOffsetCorrection = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_FIXED_TEMPO_OFFSET_CORRECTION)).toInt());
    bool bPreferencesReanalyzeOldBpm = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_REANALYZE_WHEN_SETTINGS_CHANGE)).toInt());
    bool bPreferencesFastAnalysis = static_cast<bool>(
        m_pConfig->getValueString(
            ConfigKey(BPM_CONFIG_KEY, BPM_FAST_ANALYSIS_ENABLED)).toInt());

    bool bpmLock = tio->hasBpmLock();
    if (bpmLock) {
        qDebug() << "Track is BpmLocked: Beat calculation will not start";
        return true;
    }

    QString library = m_pConfig->getValueString(
        ConfigKey(VAMP_CONFIG_KEY, VAMP_ANALYSER_BEAT_LIBRARY));
    QString pluginID = m_pConfig->getValueString(
        ConfigKey(VAMP_CONFIG_KEY, VAMP_ANALYSER_BEAT_PLUGIN_ID));

    // At first start config for QM and Vamp does not exist --> set default
    // TODO(XXX): This is no longer present in initialise. Remove?
    if (library.isEmpty() || library.isNull())
        library = "libmixxxminimal";
    if (pluginID.isEmpty() || pluginID.isNull())
        pluginID="qm-tempotracker:0";

    // If the track already has a Beats object then we need to decide whether to
    // analyze this track or not.
    BeatsPointer pBeats = tio->getBeats();
    if (pBeats) {
        QString version = pBeats->getVersion();
        QString subVersion = pBeats->getSubVersion();

        QHash<QString, QString> extraVersionInfo = getExtraVersionInfo(
            pluginID, bPreferencesFastAnalysis);
        QString newVersion = BeatFactory::getPreferredVersion(
            bPreferencesOffsetCorrection);
        QString newSubVersion = BeatFactory::getPreferredSubVersion(
            bPreferencesFixedTempo, bPreferencesOffsetCorrection,
            iMinBpm, iMaxBpm, extraVersionInfo);

        if (version == newVersion && subVersion == newSubVersion) {
            // If the version and settings have not changed then if the world is
            // sane, re-analyzing will do nothing.
            qDebug() << "Beat sub-version has not changed since previous analysis so not analyzing.";
            return true;
        } else if (bPreferencesReanalyzeOldBpm) {
            return false;
        } else if (pBeats->getBpm() == 0.0) {
            qDebug() << "BPM is 0 for track so re-analyzing despite preference settings.";
            return false;
        } else if (pBeats->findNextBeat(0) <= 0.0) {
            qDebug() << "First beat is 0 for grid so analyzing track to find first beat.";
            return false;
        } else {
            qDebug() << "Beat calculation skips analyzing because the track has"
                     << "a BPM computed by a previous Mixxx version and user"
                     << "preferences indicate we should not change it.";
            return true;
        }
    } else {
        // If we got here, we want to analyze this track.
        return false;
    }
}
Exemplo n.º 15
0
bool BpmControl::syncPhase(EngineBuffer* pOtherEngineBuffer) {
    if (!pOtherEngineBuffer) {
        return false;
    }
    TrackPointer otherTrack = pOtherEngineBuffer->getLoadedTrack();
    BeatsPointer otherBeats = otherTrack ? otherTrack->getBeats() : BeatsPointer();

    // If either track does not have beats, then we can't adjust the phase.
    if (!m_pBeats || !otherBeats) {
        return false;
    }

    // Get the file BPM of each song.
    //double dThisBpm = m_pBeats->getBpm();
    //double dOtherBpm = ControlObject::getControl(
    //ConfigKey(pOtherEngineBuffer->getGroup(), "file_bpm"))->get();

    // Get the current position of both decks
    double dThisPosition = getCurrentSample();
    double dOtherLength = ControlObject::getControl(
        ConfigKey(pOtherEngineBuffer->getGroup(), "track_samples"))->get();
    double dOtherEnginePlayPos = ControlObject::getControl(
        ConfigKey(pOtherEngineBuffer->getGroup(), "visual_playposition"))->get();
    double dOtherPosition = dOtherLength * dOtherEnginePlayPos;

    double dThisPrevBeat = m_pBeats->findPrevBeat(dThisPosition);
    double dThisNextBeat = m_pBeats->findNextBeat(dThisPosition);

    if (dThisPrevBeat == -1 || dThisNextBeat == -1 ||
            dOtherEnginePlayPos == -1 || dOtherLength == 0) {
        return false;
    }

    // Protect against the case where we are sitting exactly on the beat.
    if (dThisPrevBeat == dThisNextBeat) {
        dThisNextBeat = m_pBeats->findNthBeat(dThisPosition, 2);
    }

    double dOtherPrevBeat = otherBeats->findPrevBeat(dOtherPosition);
    double dOtherNextBeat = otherBeats->findNextBeat(dOtherPosition);

    if (dOtherPrevBeat == -1 || dOtherNextBeat == -1) {
        return false;
    }

    // Protect against the case where we are sitting exactly on the beat.
    if (dOtherPrevBeat == dOtherNextBeat) {
        dOtherNextBeat = otherBeats->findNthBeat(dOtherPosition, 2);
    }

    double dThisBeatLength = fabs(dThisNextBeat - dThisPrevBeat);
    double dOtherBeatLength = fabs(dOtherNextBeat - dOtherPrevBeat);
    double dOtherBeatFraction = (dOtherPosition - dOtherPrevBeat) / dOtherBeatLength;

    double dNewPlaypos;
    bool this_near_next = dThisNextBeat - dThisPosition <= dThisPosition - dThisPrevBeat;
    bool other_near_next = dOtherNextBeat - dOtherPosition <= dOtherPosition - dOtherPrevBeat;

    // We want our beat fraction to be identical to theirs.

    // If the two tracks have similar alignment, adjust phase is straight-
    // forward.  Use the same fraction for both beats, starting from the previous
    // beat.  But if This track is nearer to the next beat and the Other track
    // is nearer to the previous beat, use This Next beat as the starting point
    // for the phase. (ie, we pushed the sync button late).  If This track
    // is nearer to the previous beat, but the Other track is nearer to the
    // next beat, we pushed the sync button early so use the double-previous
    // beat as the basis for the adjustment.
    //
    // This makes way more sense when you're actually mixing.
    //
    // TODO(XXX) Revisit this logic once we move away from tempo-locked,
    // infinite beatgrids because the assumption that findNthBeat(-2) always
    // works will be wrong then.

    if (this_near_next == other_near_next) {
        dNewPlaypos = dThisPrevBeat + dOtherBeatFraction * dThisBeatLength;
    } else if (this_near_next && !other_near_next) {
        dNewPlaypos = dThisNextBeat + dOtherBeatFraction * dThisBeatLength;
    } else {  //!this_near_next && other_near_next
        dThisPrevBeat = m_pBeats->findNthBeat(dThisPosition, -2);
        dNewPlaypos = dThisPrevBeat + dOtherBeatFraction * dThisBeatLength;
    }

    // We might be seeking outside the loop.
    const bool loop_enabled = m_pLoopEnabled->get() > 0.0;
    const double loop_start_position = m_pLoopStartPosition->get();
    const double loop_end_position = m_pLoopEndPosition->get();

    // Cases for sanity:
    //
    // CASE 1
    // Two identical 1-beat loops, out of phase by X samples.
    // Other deck is at its loop start.
    // This deck is half way through. We want to jump forward X samples to the loop end point.
    //
    // Two identical 1-beat loop, out of phase by X samples.
    // Other deck is

    // If sync target is 50% through the beat,
    // If we are at the loop end point and hit sync, jump forward X samples.


    // TODO(rryan): Revise this with something that keeps a broader number of
    // cases in sync. This at least prevents breaking out of the loop.
    if (loop_enabled) {
        const double loop_length = loop_end_position - loop_start_position;
        if (loop_length <= 0.0) {
            return false;
        }

        // TODO(rryan): If loop_length is not a multiple of dThisBeatLength should
        // we bail and not sync phase?

        // Syncing to after the loop end.
        double end_delta = dNewPlaypos - loop_end_position;
        if (end_delta > 0) {
            int i = end_delta / loop_length;
            dNewPlaypos = loop_start_position + end_delta - i * loop_length;
        }

        // Syncing to before the loop beginning.
        double start_delta = loop_start_position - dNewPlaypos;
        if (start_delta > 0) {
            int i = start_delta / loop_length;
            dNewPlaypos = loop_end_position - start_delta + i * loop_length;
        }
    }

    seekAbs(dNewPlaypos);
    return true;
}