diff --git a/media/libaudioprocessing/AudioMixer.cpp b/media/libaudioprocessing/AudioMixer.cpp
index 2d740ab..c0b11a4 100644
--- a/media/libaudioprocessing/AudioMixer.cpp
+++ b/media/libaudioprocessing/AudioMixer.cpp
@@ -28,9 +28,6 @@
 #include <utils/Errors.h>
 #include <utils/Log.h>
 
-#include <cutils/compiler.h>
-#include <utils/Debug.h>
-
 #include <system/audio.h>
 
 #include <audio_utils/primitives.h>
@@ -59,26 +56,6 @@
 #define ALOGVV(a...) do { } while (0)
 #endif
 
-// Set kUseNewMixer to true to use the new mixer engine always. Otherwise the
-// original code will be used for stereo sinks, the new mixer for multichannel.
-static constexpr bool kUseNewMixer = true;
-
-// Set kUseFloat to true to allow floating input into the mixer engine.
-// If kUseNewMixer is false, this is ignored or may be overridden internally
-// because of downmix/upmix support.
-static constexpr bool kUseFloat = true;
-
-#ifdef FLOAT_AUX
-using TYPE_AUX = float;
-static_assert(kUseNewMixer && kUseFloat,
-        "kUseNewMixer and kUseFloat must be true for FLOAT_AUX option");
-#else
-using TYPE_AUX = int32_t; // q4.27
-#endif
-
-// TODO: remove BLOCKSIZE unit of processing - it isn't needed anymore.
-static constexpr int BLOCKSIZE = 16;
-
 // Set to default copy buffer size in frames for input processing.
 static constexpr size_t kCopyBufferFrameCount = 256;
 
@@ -86,110 +63,8 @@
 
 // ----------------------------------------------------------------------------
 
-static inline audio_format_t selectMixerInFormat(audio_format_t inputFormat __unused) {
-    return kUseFloat && kUseNewMixer ? AUDIO_FORMAT_PCM_FLOAT : AUDIO_FORMAT_PCM_16_BIT;
-}
-
-status_t AudioMixer::create(
-        int name, audio_channel_mask_t channelMask, audio_format_t format, int sessionId)
-{
-    LOG_ALWAYS_FATAL_IF(exists(name), "name %d already exists", name);
-
-    if (!isValidChannelMask(channelMask)) {
-        ALOGE("%s invalid channelMask: %#x", __func__, channelMask);
-        return BAD_VALUE;
-    }
-    if (!isValidFormat(format)) {
-        ALOGE("%s invalid format: %#x", __func__, format);
-        return BAD_VALUE;
-    }
-
-    auto t = std::make_shared<Track>();
-    {
-        // TODO: move initialization to the Track constructor.
-        // assume default parameters for the track, except where noted below
-        t->needs = 0;
-
-        // Integer volume.
-        // Currently integer volume is kept for the legacy integer mixer.
-        // Will be removed when the legacy mixer path is removed.
-        t->volume[0] = 0;
-        t->volume[1] = 0;
-        t->prevVolume[0] = 0 << 16;
-        t->prevVolume[1] = 0 << 16;
-        t->volumeInc[0] = 0;
-        t->volumeInc[1] = 0;
-        t->auxLevel = 0;
-        t->auxInc = 0;
-        t->prevAuxLevel = 0;
-
-        // Floating point volume.
-        t->mVolume[0] = 0.f;
-        t->mVolume[1] = 0.f;
-        t->mPrevVolume[0] = 0.f;
-        t->mPrevVolume[1] = 0.f;
-        t->mVolumeInc[0] = 0.;
-        t->mVolumeInc[1] = 0.;
-        t->mAuxLevel = 0.;
-        t->mAuxInc = 0.;
-        t->mPrevAuxLevel = 0.;
-
-        // no initialization needed
-        // t->frameCount
-        t->mHapticChannelMask = channelMask & AUDIO_CHANNEL_HAPTIC_ALL;
-        t->mHapticChannelCount = audio_channel_count_from_out_mask(t->mHapticChannelMask);
-        channelMask &= ~AUDIO_CHANNEL_HAPTIC_ALL;
-        t->channelCount = audio_channel_count_from_out_mask(channelMask);
-        t->enabled = false;
-        ALOGV_IF(audio_channel_mask_get_bits(channelMask) != AUDIO_CHANNEL_OUT_STEREO,
-                "Non-stereo channel mask: %d\n", channelMask);
-        t->channelMask = channelMask;
-        t->sessionId = sessionId;
-        // setBufferProvider(name, AudioBufferProvider *) is required before enable(name)
-        t->bufferProvider = NULL;
-        t->buffer.raw = NULL;
-        // no initialization needed
-        // t->buffer.frameCount
-        t->hook = NULL;
-        t->mIn = NULL;
-        t->sampleRate = mSampleRate;
-        // setParameter(name, TRACK, MAIN_BUFFER, mixBuffer) is required before enable(name)
-        t->mainBuffer = NULL;
-        t->auxBuffer = NULL;
-        t->mInputBufferProvider = NULL;
-        t->mMixerFormat = AUDIO_FORMAT_PCM_16_BIT;
-        t->mFormat = format;
-        t->mMixerInFormat = selectMixerInFormat(format);
-        t->mDownmixRequiresFormat = AUDIO_FORMAT_INVALID; // no format required
-        t->mMixerChannelMask = audio_channel_mask_from_representation_and_bits(
-                AUDIO_CHANNEL_REPRESENTATION_POSITION, AUDIO_CHANNEL_OUT_STEREO);
-        t->mMixerChannelCount = audio_channel_count_from_out_mask(t->mMixerChannelMask);
-        t->mPlaybackRate = AUDIO_PLAYBACK_RATE_DEFAULT;
-        // haptic
-        t->mHapticPlaybackEnabled = false;
-        t->mHapticIntensity = HAPTIC_SCALE_NONE;
-        t->mMixerHapticChannelMask = AUDIO_CHANNEL_NONE;
-        t->mMixerHapticChannelCount = 0;
-        t->mAdjustInChannelCount = t->channelCount + t->mHapticChannelCount;
-        t->mAdjustOutChannelCount = t->channelCount + t->mMixerHapticChannelCount;
-        t->mAdjustNonDestructiveInChannelCount = t->mAdjustOutChannelCount;
-        t->mAdjustNonDestructiveOutChannelCount = t->channelCount;
-        t->mKeepContractedChannels = false;
-        // Check the downmixing (or upmixing) requirements.
-        status_t status = t->prepareForDownmix();
-        if (status != OK) {
-            ALOGE("AudioMixer::getTrackName invalid channelMask (%#x)", channelMask);
-            return BAD_VALUE;
-        }
-        // prepareForDownmix() may change mDownmixRequiresFormat
-        ALOGVV("mMixerFormat:%#x  mMixerInFormat:%#x\n", t->mMixerFormat, t->mMixerInFormat);
-        t->prepareForReformat();
-        t->prepareForAdjustChannelsNonDestructive(mFrameCount);
-        t->prepareForAdjustChannels();
-
-        mTracks[name] = t;
-        return OK;
-    }
+bool AudioMixer::isValidChannelMask(audio_channel_mask_t channelMask) const {
+    return audio_channel_mask_is_valid(channelMask); // the RemixBufferProvider is flexible.
 }
 
 // Called when channel masks have changed for a track name
@@ -198,7 +73,7 @@
 bool AudioMixer::setChannelMasks(int name,
         audio_channel_mask_t trackChannelMask, audio_channel_mask_t mixerChannelMask) {
     LOG_ALWAYS_FATAL_IF(!exists(name), "invalid name: %d", name);
-    const std::shared_ptr<Track> &track = mTracks[name];
+    const std::shared_ptr<Track> &track = getTrack(name);
 
     if (trackChannelMask == (track->channelMask | track->mHapticChannelMask)
             && mixerChannelMask == (track->mMixerChannelMask | track->mMixerHapticChannelMask)) {
@@ -255,14 +130,8 @@
     track->prepareForAdjustChannelsNonDestructive(mFrameCount);
     track->prepareForAdjustChannels();
 
-    if (track->mResampler.get() != nullptr) {
-        // resampler channels may have changed.
-        const uint32_t resetToSampleRate = track->sampleRate;
-        track->mResampler.reset(nullptr);
-        track->sampleRate = mSampleRate; // without resampler, track rate is device sample rate.
-        // recreate the resampler with updated format, channels, saved sampleRate.
-        track->setResampler(resetToSampleRate /*trackSampleRate*/, mSampleRate /*devSampleRate*/);
-    }
+    // Resampler channels may have changed.
+    track->recreateResampler(mSampleRate);
     return true;
 }
 
@@ -477,171 +346,10 @@
     }
 }
 
-void AudioMixer::destroy(int name)
-{
-    LOG_ALWAYS_FATAL_IF(!exists(name), "invalid name: %d", name);
-    ALOGV("deleteTrackName(%d)", name);
-
-    if (mTracks[name]->enabled) {
-        invalidate();
-    }
-    mTracks.erase(name); // deallocate track
-}
-
-void AudioMixer::enable(int name)
-{
-    LOG_ALWAYS_FATAL_IF(!exists(name), "invalid name: %d", name);
-    const std::shared_ptr<Track> &track = mTracks[name];
-
-    if (!track->enabled) {
-        track->enabled = true;
-        ALOGV("enable(%d)", name);
-        invalidate();
-    }
-}
-
-void AudioMixer::disable(int name)
-{
-    LOG_ALWAYS_FATAL_IF(!exists(name), "invalid name: %d", name);
-    const std::shared_ptr<Track> &track = mTracks[name];
-
-    if (track->enabled) {
-        track->enabled = false;
-        ALOGV("disable(%d)", name);
-        invalidate();
-    }
-}
-
-/* Sets the volume ramp variables for the AudioMixer.
- *
- * The volume ramp variables are used to transition from the previous
- * volume to the set volume.  ramp controls the duration of the transition.
- * Its value is typically one state framecount period, but may also be 0,
- * meaning "immediate."
- *
- * FIXME: 1) Volume ramp is enabled only if there is a nonzero integer increment
- * even if there is a nonzero floating point increment (in that case, the volume
- * change is immediate).  This restriction should be changed when the legacy mixer
- * is removed (see #2).
- * FIXME: 2) Integer volume variables are used for Legacy mixing and should be removed
- * when no longer needed.
- *
- * @param newVolume set volume target in floating point [0.0, 1.0].
- * @param ramp number of frames to increment over. if ramp is 0, the volume
- * should be set immediately.  Currently ramp should not exceed 65535 (frames).
- * @param pIntSetVolume pointer to the U4.12 integer target volume, set on return.
- * @param pIntPrevVolume pointer to the U4.28 integer previous volume, set on return.
- * @param pIntVolumeInc pointer to the U4.28 increment per output audio frame, set on return.
- * @param pSetVolume pointer to the float target volume, set on return.
- * @param pPrevVolume pointer to the float previous volume, set on return.
- * @param pVolumeInc pointer to the float increment per output audio frame, set on return.
- * @return true if the volume has changed, false if volume is same.
- */
-static inline bool setVolumeRampVariables(float newVolume, int32_t ramp,
-        int16_t *pIntSetVolume, int32_t *pIntPrevVolume, int32_t *pIntVolumeInc,
-        float *pSetVolume, float *pPrevVolume, float *pVolumeInc) {
-    // check floating point volume to see if it is identical to the previously
-    // set volume.
-    // We do not use a tolerance here (and reject changes too small)
-    // as it may be confusing to use a different value than the one set.
-    // If the resulting volume is too small to ramp, it is a direct set of the volume.
-    if (newVolume == *pSetVolume) {
-        return false;
-    }
-    if (newVolume < 0) {
-        newVolume = 0; // should not have negative volumes
-    } else {
-        switch (fpclassify(newVolume)) {
-        case FP_SUBNORMAL:
-        case FP_NAN:
-            newVolume = 0;
-            break;
-        case FP_ZERO:
-            break; // zero volume is fine
-        case FP_INFINITE:
-            // Infinite volume could be handled consistently since
-            // floating point math saturates at infinities,
-            // but we limit volume to unity gain float.
-            // ramp = 0; break;
-            //
-            newVolume = AudioMixer::UNITY_GAIN_FLOAT;
-            break;
-        case FP_NORMAL:
-        default:
-            // Floating point does not have problems with overflow wrap
-            // that integer has.  However, we limit the volume to
-            // unity gain here.
-            // TODO: Revisit the volume limitation and perhaps parameterize.
-            if (newVolume > AudioMixer::UNITY_GAIN_FLOAT) {
-                newVolume = AudioMixer::UNITY_GAIN_FLOAT;
-            }
-            break;
-        }
-    }
-
-    // set floating point volume ramp
-    if (ramp != 0) {
-        // when the ramp completes, *pPrevVolume is set to *pSetVolume, so there
-        // is no computational mismatch; hence equality is checked here.
-        ALOGD_IF(*pPrevVolume != *pSetVolume, "previous float ramp hasn't finished,"
-                " prev:%f  set_to:%f", *pPrevVolume, *pSetVolume);
-        const float inc = (newVolume - *pPrevVolume) / ramp; // could be inf, nan, subnormal
-        // could be inf, cannot be nan, subnormal
-        const float maxv = std::max(newVolume, *pPrevVolume);
-
-        if (isnormal(inc) // inc must be a normal number (no subnormals, infinite, nan)
-                && maxv + inc != maxv) { // inc must make forward progress
-            *pVolumeInc = inc;
-            // ramp is set now.
-            // Note: if newVolume is 0, then near the end of the ramp,
-            // it may be possible that the ramped volume may be subnormal or
-            // temporarily negative by a small amount or subnormal due to floating
-            // point inaccuracies.
-        } else {
-            ramp = 0; // ramp not allowed
-        }
-    }
-
-    // compute and check integer volume, no need to check negative values
-    // The integer volume is limited to "unity_gain" to avoid wrapping and other
-    // audio artifacts, so it never reaches the range limit of U4.28.
-    // We safely use signed 16 and 32 bit integers here.
-    const float scaledVolume = newVolume * AudioMixer::UNITY_GAIN_INT; // not neg, subnormal, nan
-    const int32_t intVolume = (scaledVolume >= (float)AudioMixer::UNITY_GAIN_INT) ?
-            AudioMixer::UNITY_GAIN_INT : (int32_t)scaledVolume;
-
-    // set integer volume ramp
-    if (ramp != 0) {
-        // integer volume is U4.12 (to use 16 bit multiplies), but ramping uses U4.28.
-        // when the ramp completes, *pIntPrevVolume is set to *pIntSetVolume << 16, so there
-        // is no computational mismatch; hence equality is checked here.
-        ALOGD_IF(*pIntPrevVolume != *pIntSetVolume << 16, "previous int ramp hasn't finished,"
-                " prev:%d  set_to:%d", *pIntPrevVolume, *pIntSetVolume << 16);
-        const int32_t inc = ((intVolume << 16) - *pIntPrevVolume) / ramp;
-
-        if (inc != 0) { // inc must make forward progress
-            *pIntVolumeInc = inc;
-        } else {
-            ramp = 0; // ramp not allowed
-        }
-    }
-
-    // if no ramp, or ramp not allowed, then clear float and integer increments
-    if (ramp == 0) {
-        *pVolumeInc = 0;
-        *pPrevVolume = newVolume;
-        *pIntVolumeInc = 0;
-        *pIntPrevVolume = intVolume << 16;
-    }
-    *pSetVolume = newVolume;
-    *pIntSetVolume = intVolume;
-    return true;
-}
-
 void AudioMixer::setParameter(int name, int target, int param, void *value)
 {
     LOG_ALWAYS_FATAL_IF(!exists(name), "invalid name: %d", name);
-    const std::shared_ptr<Track> &track = mTracks[name];
+    const std::shared_ptr<Track> &track = getTrack(name);
 
     int valueInt = static_cast<int>(reinterpret_cast<uintptr_t>(value));
     int32_t *valueBuf = reinterpret_cast<int32_t*>(value);
@@ -670,11 +378,7 @@
             }
             break;
         case AUX_BUFFER:
-            if (track->auxBuffer != valueBuf) {
-                track->auxBuffer = valueBuf;
-                ALOGV("setParameter(TRACK, AUX_BUFFER, %p)", valueBuf);
-                invalidate();
-            }
+            AudioMixerBase::setParameter(name, target, param, value);
             break;
         case FORMAT: {
             audio_format_t format = static_cast<audio_format_t>(valueInt);
@@ -730,61 +434,9 @@
         break;
 
     case RESAMPLE:
-        switch (param) {
-        case SAMPLE_RATE:
-            ALOG_ASSERT(valueInt > 0, "bad sample rate %d", valueInt);
-            if (track->setResampler(uint32_t(valueInt), mSampleRate)) {
-                ALOGV("setParameter(RESAMPLE, SAMPLE_RATE, %u)",
-                        uint32_t(valueInt));
-                invalidate();
-            }
-            break;
-        case RESET:
-            track->resetResampler();
-            invalidate();
-            break;
-        case REMOVE:
-            track->mResampler.reset(nullptr);
-            track->sampleRate = mSampleRate;
-            invalidate();
-            break;
-        default:
-            LOG_ALWAYS_FATAL("setParameter resample: bad param %d", param);
-        }
-        break;
-
     case RAMP_VOLUME:
     case VOLUME:
-        switch (param) {
-        case AUXLEVEL:
-            if (setVolumeRampVariables(*reinterpret_cast<float*>(value),
-                    target == RAMP_VOLUME ? mFrameCount : 0,
-                    &track->auxLevel, &track->prevAuxLevel, &track->auxInc,
-                    &track->mAuxLevel, &track->mPrevAuxLevel, &track->mAuxInc)) {
-                ALOGV("setParameter(%s, AUXLEVEL: %04x)",
-                        target == VOLUME ? "VOLUME" : "RAMP_VOLUME", track->auxLevel);
-                invalidate();
-            }
-            break;
-        default:
-            if ((unsigned)param >= VOLUME0 && (unsigned)param < VOLUME0 + MAX_NUM_VOLUMES) {
-                if (setVolumeRampVariables(*reinterpret_cast<float*>(value),
-                        target == RAMP_VOLUME ? mFrameCount : 0,
-                        &track->volume[param - VOLUME0],
-                        &track->prevVolume[param - VOLUME0],
-                        &track->volumeInc[param - VOLUME0],
-                        &track->mVolume[param - VOLUME0],
-                        &track->mPrevVolume[param - VOLUME0],
-                        &track->mVolumeInc[param - VOLUME0])) {
-                    ALOGV("setParameter(%s, VOLUME%d: %04x)",
-                            target == VOLUME ? "VOLUME" : "RAMP_VOLUME", param - VOLUME0,
-                                    track->volume[param - VOLUME0]);
-                    invalidate();
-                }
-            } else {
-                LOG_ALWAYS_FATAL("setParameter volume: bad param %d", param);
-            }
-        }
+        AudioMixerBase::setParameter(name, target, param, value);
         break;
     case TIMESTRETCH:
         switch (param) {
@@ -814,43 +466,6 @@
     }
 }
 
-bool AudioMixer::Track::setResampler(uint32_t trackSampleRate, uint32_t devSampleRate)
-{
-    if (trackSampleRate != devSampleRate || mResampler.get() != nullptr) {
-        if (sampleRate != trackSampleRate) {
-            sampleRate = trackSampleRate;
-            if (mResampler.get() == nullptr) {
-                ALOGV("Creating resampler from track %d Hz to device %d Hz",
-                        trackSampleRate, devSampleRate);
-                AudioResampler::src_quality quality;
-                // force lowest quality level resampler if use case isn't music or video
-                // FIXME this is flawed for dynamic sample rates, as we choose the resampler
-                // quality level based on the initial ratio, but that could change later.
-                // Should have a way to distinguish tracks with static ratios vs. dynamic ratios.
-                if (isMusicRate(trackSampleRate)) {
-                    quality = AudioResampler::DEFAULT_QUALITY;
-                } else {
-                    quality = AudioResampler::DYN_LOW_QUALITY;
-                }
-
-                // TODO: Remove MONO_HACK. Resampler sees #channels after the downmixer
-                // but if none exists, it is the channel count (1 for mono).
-                const int resamplerChannelCount = mDownmixerBufferProvider.get() != nullptr
-                        ? mMixerChannelCount : channelCount;
-                ALOGVV("Creating resampler:"
-                        " format(%#x) channels(%d) devSampleRate(%u) quality(%d)\n",
-                        mMixerInFormat, resamplerChannelCount, devSampleRate, quality);
-                mResampler.reset(AudioResampler::create(
-                        mMixerInFormat,
-                        resamplerChannelCount,
-                        devSampleRate, quality));
-            }
-            return true;
-        }
-    }
-    return false;
-}
-
 bool AudioMixer::Track::setPlaybackRate(const AudioPlaybackRate &playbackRate)
 {
     if ((mTimestretchBufferProvider.get() == nullptr &&
@@ -863,8 +478,7 @@
     if (mTimestretchBufferProvider.get() == nullptr) {
         // TODO: Remove MONO_HACK. Resampler sees #channels after the downmixer
         // but if none exists, it is the channel count (1 for mono).
-        const int timestretchChannelCount = mDownmixerBufferProvider.get() != nullptr
-                ? mMixerChannelCount : channelCount;
+        const int timestretchChannelCount = getOutputChannelCount();
         mTimestretchBufferProvider.reset(new TimestretchBufferProvider(timestretchChannelCount,
                 mMixerInFormat, sampleRate, playbackRate));
         reconfigureBufferProviders();
@@ -875,92 +489,10 @@
     return true;
 }
 
-/* Checks to see if the volume ramp has completed and clears the increment
- * variables appropriately.
- *
- * FIXME: There is code to handle int/float ramp variable switchover should it not
- * complete within a mixer buffer processing call, but it is preferred to avoid switchover
- * due to precision issues.  The switchover code is included for legacy code purposes
- * and can be removed once the integer volume is removed.
- *
- * It is not sufficient to clear only the volumeInc integer variable because
- * if one channel requires ramping, all channels are ramped.
- *
- * There is a bit of duplicated code here, but it keeps backward compatibility.
- */
-inline void AudioMixer::Track::adjustVolumeRamp(bool aux, bool useFloat)
-{
-    if (useFloat) {
-        for (uint32_t i = 0; i < MAX_NUM_VOLUMES; i++) {
-            if ((mVolumeInc[i] > 0 && mPrevVolume[i] + mVolumeInc[i] >= mVolume[i]) ||
-                     (mVolumeInc[i] < 0 && mPrevVolume[i] + mVolumeInc[i] <= mVolume[i])) {
-                volumeInc[i] = 0;
-                prevVolume[i] = volume[i] << 16;
-                mVolumeInc[i] = 0.;
-                mPrevVolume[i] = mVolume[i];
-            } else {
-                //ALOGV("ramp: %f %f %f", mVolume[i], mPrevVolume[i], mVolumeInc[i]);
-                prevVolume[i] = u4_28_from_float(mPrevVolume[i]);
-            }
-        }
-    } else {
-        for (uint32_t i = 0; i < MAX_NUM_VOLUMES; i++) {
-            if (((volumeInc[i]>0) && (((prevVolume[i]+volumeInc[i])>>16) >= volume[i])) ||
-                    ((volumeInc[i]<0) && (((prevVolume[i]+volumeInc[i])>>16) <= volume[i]))) {
-                volumeInc[i] = 0;
-                prevVolume[i] = volume[i] << 16;
-                mVolumeInc[i] = 0.;
-                mPrevVolume[i] = mVolume[i];
-            } else {
-                //ALOGV("ramp: %d %d %d", volume[i] << 16, prevVolume[i], volumeInc[i]);
-                mPrevVolume[i]  = float_from_u4_28(prevVolume[i]);
-            }
-        }
-    }
-
-    if (aux) {
-#ifdef FLOAT_AUX
-        if (useFloat) {
-            if ((mAuxInc > 0.f && mPrevAuxLevel + mAuxInc >= mAuxLevel) ||
-                    (mAuxInc < 0.f && mPrevAuxLevel + mAuxInc <= mAuxLevel)) {
-                auxInc = 0;
-                prevAuxLevel = auxLevel << 16;
-                mAuxInc = 0.f;
-                mPrevAuxLevel = mAuxLevel;
-            }
-        } else
-#endif
-        if ((auxInc > 0 && ((prevAuxLevel + auxInc) >> 16) >= auxLevel) ||
-                (auxInc < 0 && ((prevAuxLevel + auxInc) >> 16) <= auxLevel)) {
-            auxInc = 0;
-            prevAuxLevel = auxLevel << 16;
-            mAuxInc = 0.f;
-            mPrevAuxLevel = mAuxLevel;
-        }
-    }
-}
-
-size_t AudioMixer::getUnreleasedFrames(int name) const
-{
-    const auto it = mTracks.find(name);
-    if (it != mTracks.end()) {
-        return it->second->getUnreleasedFrames();
-    }
-    return 0;
-}
-
-std::string AudioMixer::trackNames() const {
-    std::stringstream ss;
-    for (const auto &pair : mTracks) {
-        ss << pair.first << " ";
-    }
-    return ss.str();
-}
-
 void AudioMixer::setBufferProvider(int name, AudioBufferProvider* bufferProvider)
 {
     LOG_ALWAYS_FATAL_IF(!exists(name), "invalid name: %d", name);
-    const std::shared_ptr<Track> &track = mTracks[name];
+    const std::shared_ptr<Track> &track = getTrack(name);
 
     if (track->mInputBufferProvider == bufferProvider) {
         return; // don't reset any buffer providers if identical.
@@ -984,679 +516,6 @@
     track->reconfigureBufferProviders();
 }
 
-void AudioMixer::process__validate()
-{
-    // TODO: fix all16BitsStereNoResample logic to
-    // either properly handle muted tracks (it should ignore them)
-    // or remove altogether as an obsolete optimization.
-    bool all16BitsStereoNoResample = true;
-    bool resampling = false;
-    bool volumeRamp = false;
-
-    mEnabled.clear();
-    mGroups.clear();
-    for (const auto &pair : mTracks) {
-        const int name = pair.first;
-        const std::shared_ptr<Track> &t = pair.second;
-        if (!t->enabled) continue;
-
-        mEnabled.emplace_back(name);  // we add to mEnabled in order of name.
-        mGroups[t->mainBuffer].emplace_back(name); // mGroups also in order of name.
-
-        uint32_t n = 0;
-        // FIXME can overflow (mask is only 3 bits)
-        n |= NEEDS_CHANNEL_1 + t->channelCount - 1;
-        if (t->doesResample()) {
-            n |= NEEDS_RESAMPLE;
-        }
-        if (t->auxLevel != 0 && t->auxBuffer != NULL) {
-            n |= NEEDS_AUX;
-        }
-
-        if (t->volumeInc[0]|t->volumeInc[1]) {
-            volumeRamp = true;
-        } else if (!t->doesResample() && t->volumeRL == 0) {
-            n |= NEEDS_MUTE;
-        }
-        t->needs = n;
-
-        if (n & NEEDS_MUTE) {
-            t->hook = &Track::track__nop;
-        } else {
-            if (n & NEEDS_AUX) {
-                all16BitsStereoNoResample = false;
-            }
-            if (n & NEEDS_RESAMPLE) {
-                all16BitsStereoNoResample = false;
-                resampling = true;
-                t->hook = Track::getTrackHook(TRACKTYPE_RESAMPLE, t->mMixerChannelCount,
-                        t->mMixerInFormat, t->mMixerFormat);
-                ALOGV_IF((n & NEEDS_CHANNEL_COUNT__MASK) > NEEDS_CHANNEL_2,
-                        "Track %d needs downmix + resample", name);
-            } else {
-                if ((n & NEEDS_CHANNEL_COUNT__MASK) == NEEDS_CHANNEL_1){
-                    t->hook = Track::getTrackHook(
-                            (t->mMixerChannelMask == AUDIO_CHANNEL_OUT_STEREO  // TODO: MONO_HACK
-                                    && t->channelMask == AUDIO_CHANNEL_OUT_MONO)
-                                ? TRACKTYPE_NORESAMPLEMONO : TRACKTYPE_NORESAMPLE,
-                            t->mMixerChannelCount,
-                            t->mMixerInFormat, t->mMixerFormat);
-                    all16BitsStereoNoResample = false;
-                }
-                if ((n & NEEDS_CHANNEL_COUNT__MASK) >= NEEDS_CHANNEL_2){
-                    t->hook = Track::getTrackHook(TRACKTYPE_NORESAMPLE, t->mMixerChannelCount,
-                            t->mMixerInFormat, t->mMixerFormat);
-                    ALOGV_IF((n & NEEDS_CHANNEL_COUNT__MASK) > NEEDS_CHANNEL_2,
-                            "Track %d needs downmix", name);
-                }
-            }
-        }
-    }
-
-    // select the processing hooks
-    mHook = &AudioMixer::process__nop;
-    if (mEnabled.size() > 0) {
-        if (resampling) {
-            if (mOutputTemp.get() == nullptr) {
-                mOutputTemp.reset(new int32_t[MAX_NUM_CHANNELS * mFrameCount]);
-            }
-            if (mResampleTemp.get() == nullptr) {
-                mResampleTemp.reset(new int32_t[MAX_NUM_CHANNELS * mFrameCount]);
-            }
-            mHook = &AudioMixer::process__genericResampling;
-        } else {
-            // we keep temp arrays around.
-            mHook = &AudioMixer::process__genericNoResampling;
-            if (all16BitsStereoNoResample && !volumeRamp) {
-                if (mEnabled.size() == 1) {
-                    const std::shared_ptr<Track> &t = mTracks[mEnabled[0]];
-                    if ((t->needs & NEEDS_MUTE) == 0) {
-                        // The check prevents a muted track from acquiring a process hook.
-                        //
-                        // This is dangerous if the track is MONO as that requires
-                        // special case handling due to implicit channel duplication.
-                        // Stereo or Multichannel should actually be fine here.
-                        mHook = getProcessHook(PROCESSTYPE_NORESAMPLEONETRACK,
-                                t->mMixerChannelCount, t->mMixerInFormat, t->mMixerFormat);
-                    }
-                }
-            }
-        }
-    }
-
-    ALOGV("mixer configuration change: %zu "
-        "all16BitsStereoNoResample=%d, resampling=%d, volumeRamp=%d",
-        mEnabled.size(), all16BitsStereoNoResample, resampling, volumeRamp);
-
-    process();
-
-    // Now that the volume ramp has been done, set optimal state and
-    // track hooks for subsequent mixer process
-    if (mEnabled.size() > 0) {
-        bool allMuted = true;
-
-        for (const int name : mEnabled) {
-            const std::shared_ptr<Track> &t = mTracks[name];
-            if (!t->doesResample() && t->volumeRL == 0) {
-                t->needs |= NEEDS_MUTE;
-                t->hook = &Track::track__nop;
-            } else {
-                allMuted = false;
-            }
-        }
-        if (allMuted) {
-            mHook = &AudioMixer::process__nop;
-        } else if (all16BitsStereoNoResample) {
-            if (mEnabled.size() == 1) {
-                //const int i = 31 - __builtin_clz(enabledTracks);
-                const std::shared_ptr<Track> &t = mTracks[mEnabled[0]];
-                // Muted single tracks handled by allMuted above.
-                mHook = getProcessHook(PROCESSTYPE_NORESAMPLEONETRACK,
-                        t->mMixerChannelCount, t->mMixerInFormat, t->mMixerFormat);
-            }
-        }
-    }
-}
-
-void AudioMixer::Track::track__genericResample(
-        int32_t* out, size_t outFrameCount, int32_t* temp, int32_t* aux)
-{
-    ALOGVV("track__genericResample\n");
-    mResampler->setSampleRate(sampleRate);
-
-    // ramp gain - resample to temp buffer and scale/mix in 2nd step
-    if (aux != NULL) {
-        // always resample with unity gain when sending to auxiliary buffer to be able
-        // to apply send level after resampling
-        mResampler->setVolume(UNITY_GAIN_FLOAT, UNITY_GAIN_FLOAT);
-        memset(temp, 0, outFrameCount * mMixerChannelCount * sizeof(int32_t));
-        mResampler->resample(temp, outFrameCount, bufferProvider);
-        if (CC_UNLIKELY(volumeInc[0]|volumeInc[1]|auxInc)) {
-            volumeRampStereo(out, outFrameCount, temp, aux);
-        } else {
-            volumeStereo(out, outFrameCount, temp, aux);
-        }
-    } else {
-        if (CC_UNLIKELY(volumeInc[0]|volumeInc[1])) {
-            mResampler->setVolume(UNITY_GAIN_FLOAT, UNITY_GAIN_FLOAT);
-            memset(temp, 0, outFrameCount * MAX_NUM_CHANNELS * sizeof(int32_t));
-            mResampler->resample(temp, outFrameCount, bufferProvider);
-            volumeRampStereo(out, outFrameCount, temp, aux);
-        }
-
-        // constant gain
-        else {
-            mResampler->setVolume(mVolume[0], mVolume[1]);
-            mResampler->resample(out, outFrameCount, bufferProvider);
-        }
-    }
-}
-
-void AudioMixer::Track::track__nop(int32_t* out __unused,
-        size_t outFrameCount __unused, int32_t* temp __unused, int32_t* aux __unused)
-{
-}
-
-void AudioMixer::Track::volumeRampStereo(
-        int32_t* out, size_t frameCount, int32_t* temp, int32_t* aux)
-{
-    int32_t vl = prevVolume[0];
-    int32_t vr = prevVolume[1];
-    const int32_t vlInc = volumeInc[0];
-    const int32_t vrInc = volumeInc[1];
-
-    //ALOGD("[0] %p: inc=%f, v0=%f, v1=%d, final=%f, count=%d",
-    //        t, vlInc/65536.0f, vl/65536.0f, volume[0],
-    //       (vl + vlInc*frameCount)/65536.0f, frameCount);
-
-    // ramp volume
-    if (CC_UNLIKELY(aux != NULL)) {
-        int32_t va = prevAuxLevel;
-        const int32_t vaInc = auxInc;
-        int32_t l;
-        int32_t r;
-
-        do {
-            l = (*temp++ >> 12);
-            r = (*temp++ >> 12);
-            *out++ += (vl >> 16) * l;
-            *out++ += (vr >> 16) * r;
-            *aux++ += (va >> 17) * (l + r);
-            vl += vlInc;
-            vr += vrInc;
-            va += vaInc;
-        } while (--frameCount);
-        prevAuxLevel = va;
-    } else {
-        do {
-            *out++ += (vl >> 16) * (*temp++ >> 12);
-            *out++ += (vr >> 16) * (*temp++ >> 12);
-            vl += vlInc;
-            vr += vrInc;
-        } while (--frameCount);
-    }
-    prevVolume[0] = vl;
-    prevVolume[1] = vr;
-    adjustVolumeRamp(aux != NULL);
-}
-
-void AudioMixer::Track::volumeStereo(
-        int32_t* out, size_t frameCount, int32_t* temp, int32_t* aux)
-{
-    const int16_t vl = volume[0];
-    const int16_t vr = volume[1];
-
-    if (CC_UNLIKELY(aux != NULL)) {
-        const int16_t va = auxLevel;
-        do {
-            int16_t l = (int16_t)(*temp++ >> 12);
-            int16_t r = (int16_t)(*temp++ >> 12);
-            out[0] = mulAdd(l, vl, out[0]);
-            int16_t a = (int16_t)(((int32_t)l + r) >> 1);
-            out[1] = mulAdd(r, vr, out[1]);
-            out += 2;
-            aux[0] = mulAdd(a, va, aux[0]);
-            aux++;
-        } while (--frameCount);
-    } else {
-        do {
-            int16_t l = (int16_t)(*temp++ >> 12);
-            int16_t r = (int16_t)(*temp++ >> 12);
-            out[0] = mulAdd(l, vl, out[0]);
-            out[1] = mulAdd(r, vr, out[1]);
-            out += 2;
-        } while (--frameCount);
-    }
-}
-
-void AudioMixer::Track::track__16BitsStereo(
-        int32_t* out, size_t frameCount, int32_t* temp __unused, int32_t* aux)
-{
-    ALOGVV("track__16BitsStereo\n");
-    const int16_t *in = static_cast<const int16_t *>(mIn);
-
-    if (CC_UNLIKELY(aux != NULL)) {
-        int32_t l;
-        int32_t r;
-        // ramp gain
-        if (CC_UNLIKELY(volumeInc[0]|volumeInc[1]|auxInc)) {
-            int32_t vl = prevVolume[0];
-            int32_t vr = prevVolume[1];
-            int32_t va = prevAuxLevel;
-            const int32_t vlInc = volumeInc[0];
-            const int32_t vrInc = volumeInc[1];
-            const int32_t vaInc = auxInc;
-            // ALOGD("[1] %p: inc=%f, v0=%f, v1=%d, final=%f, count=%d",
-            //        t, vlInc/65536.0f, vl/65536.0f, volume[0],
-            //        (vl + vlInc*frameCount)/65536.0f, frameCount);
-
-            do {
-                l = (int32_t)*in++;
-                r = (int32_t)*in++;
-                *out++ += (vl >> 16) * l;
-                *out++ += (vr >> 16) * r;
-                *aux++ += (va >> 17) * (l + r);
-                vl += vlInc;
-                vr += vrInc;
-                va += vaInc;
-            } while (--frameCount);
-
-            prevVolume[0] = vl;
-            prevVolume[1] = vr;
-            prevAuxLevel = va;
-            adjustVolumeRamp(true);
-        }
-
-        // constant gain
-        else {
-            const uint32_t vrl = volumeRL;
-            const int16_t va = (int16_t)auxLevel;
-            do {
-                uint32_t rl = *reinterpret_cast<const uint32_t *>(in);
-                int16_t a = (int16_t)(((int32_t)in[0] + in[1]) >> 1);
-                in += 2;
-                out[0] = mulAddRL(1, rl, vrl, out[0]);
-                out[1] = mulAddRL(0, rl, vrl, out[1]);
-                out += 2;
-                aux[0] = mulAdd(a, va, aux[0]);
-                aux++;
-            } while (--frameCount);
-        }
-    } else {
-        // ramp gain
-        if (CC_UNLIKELY(volumeInc[0]|volumeInc[1])) {
-            int32_t vl = prevVolume[0];
-            int32_t vr = prevVolume[1];
-            const int32_t vlInc = volumeInc[0];
-            const int32_t vrInc = volumeInc[1];
-
-            // ALOGD("[1] %p: inc=%f, v0=%f, v1=%d, final=%f, count=%d",
-            //        t, vlInc/65536.0f, vl/65536.0f, volume[0],
-            //        (vl + vlInc*frameCount)/65536.0f, frameCount);
-
-            do {
-                *out++ += (vl >> 16) * (int32_t) *in++;
-                *out++ += (vr >> 16) * (int32_t) *in++;
-                vl += vlInc;
-                vr += vrInc;
-            } while (--frameCount);
-
-            prevVolume[0] = vl;
-            prevVolume[1] = vr;
-            adjustVolumeRamp(false);
-        }
-
-        // constant gain
-        else {
-            const uint32_t vrl = volumeRL;
-            do {
-                uint32_t rl = *reinterpret_cast<const uint32_t *>(in);
-                in += 2;
-                out[0] = mulAddRL(1, rl, vrl, out[0]);
-                out[1] = mulAddRL(0, rl, vrl, out[1]);
-                out += 2;
-            } while (--frameCount);
-        }
-    }
-    mIn = in;
-}
-
-void AudioMixer::Track::track__16BitsMono(
-        int32_t* out, size_t frameCount, int32_t* temp __unused, int32_t* aux)
-{
-    ALOGVV("track__16BitsMono\n");
-    const int16_t *in = static_cast<int16_t const *>(mIn);
-
-    if (CC_UNLIKELY(aux != NULL)) {
-        // ramp gain
-        if (CC_UNLIKELY(volumeInc[0]|volumeInc[1]|auxInc)) {
-            int32_t vl = prevVolume[0];
-            int32_t vr = prevVolume[1];
-            int32_t va = prevAuxLevel;
-            const int32_t vlInc = volumeInc[0];
-            const int32_t vrInc = volumeInc[1];
-            const int32_t vaInc = auxInc;
-
-            // ALOGD("[2] %p: inc=%f, v0=%f, v1=%d, final=%f, count=%d",
-            //         t, vlInc/65536.0f, vl/65536.0f, volume[0],
-            //         (vl + vlInc*frameCount)/65536.0f, frameCount);
-
-            do {
-                int32_t l = *in++;
-                *out++ += (vl >> 16) * l;
-                *out++ += (vr >> 16) * l;
-                *aux++ += (va >> 16) * l;
-                vl += vlInc;
-                vr += vrInc;
-                va += vaInc;
-            } while (--frameCount);
-
-            prevVolume[0] = vl;
-            prevVolume[1] = vr;
-            prevAuxLevel = va;
-            adjustVolumeRamp(true);
-        }
-        // constant gain
-        else {
-            const int16_t vl = volume[0];
-            const int16_t vr = volume[1];
-            const int16_t va = (int16_t)auxLevel;
-            do {
-                int16_t l = *in++;
-                out[0] = mulAdd(l, vl, out[0]);
-                out[1] = mulAdd(l, vr, out[1]);
-                out += 2;
-                aux[0] = mulAdd(l, va, aux[0]);
-                aux++;
-            } while (--frameCount);
-        }
-    } else {
-        // ramp gain
-        if (CC_UNLIKELY(volumeInc[0]|volumeInc[1])) {
-            int32_t vl = prevVolume[0];
-            int32_t vr = prevVolume[1];
-            const int32_t vlInc = volumeInc[0];
-            const int32_t vrInc = volumeInc[1];
-
-            // ALOGD("[2] %p: inc=%f, v0=%f, v1=%d, final=%f, count=%d",
-            //         t, vlInc/65536.0f, vl/65536.0f, volume[0],
-            //         (vl + vlInc*frameCount)/65536.0f, frameCount);
-
-            do {
-                int32_t l = *in++;
-                *out++ += (vl >> 16) * l;
-                *out++ += (vr >> 16) * l;
-                vl += vlInc;
-                vr += vrInc;
-            } while (--frameCount);
-
-            prevVolume[0] = vl;
-            prevVolume[1] = vr;
-            adjustVolumeRamp(false);
-        }
-        // constant gain
-        else {
-            const int16_t vl = volume[0];
-            const int16_t vr = volume[1];
-            do {
-                int16_t l = *in++;
-                out[0] = mulAdd(l, vl, out[0]);
-                out[1] = mulAdd(l, vr, out[1]);
-                out += 2;
-            } while (--frameCount);
-        }
-    }
-    mIn = in;
-}
-
-// no-op case
-void AudioMixer::process__nop()
-{
-    ALOGVV("process__nop\n");
-
-    for (const auto &pair : mGroups) {
-        // process by group of tracks with same output buffer to
-        // avoid multiple memset() on same buffer
-        const auto &group = pair.second;
-
-        const std::shared_ptr<Track> &t = mTracks[group[0]];
-        memset(t->mainBuffer, 0,
-                mFrameCount * audio_bytes_per_frame(
-                        t->mMixerChannelCount + t->mMixerHapticChannelCount, t->mMixerFormat));
-
-        // now consume data
-        for (const int name : group) {
-            const std::shared_ptr<Track> &t = mTracks[name];
-            size_t outFrames = mFrameCount;
-            while (outFrames) {
-                t->buffer.frameCount = outFrames;
-                t->bufferProvider->getNextBuffer(&t->buffer);
-                if (t->buffer.raw == NULL) break;
-                outFrames -= t->buffer.frameCount;
-                t->bufferProvider->releaseBuffer(&t->buffer);
-            }
-        }
-    }
-}
-
-// generic code without resampling
-void AudioMixer::process__genericNoResampling()
-{
-    ALOGVV("process__genericNoResampling\n");
-    int32_t outTemp[BLOCKSIZE * MAX_NUM_CHANNELS] __attribute__((aligned(32)));
-
-    for (const auto &pair : mGroups) {
-        // process by group of tracks with same output main buffer to
-        // avoid multiple memset() on same buffer
-        const auto &group = pair.second;
-
-        // acquire buffer
-        for (const int name : group) {
-            const std::shared_ptr<Track> &t = mTracks[name];
-            t->buffer.frameCount = mFrameCount;
-            t->bufferProvider->getNextBuffer(&t->buffer);
-            t->frameCount = t->buffer.frameCount;
-            t->mIn = t->buffer.raw;
-        }
-
-        int32_t *out = (int *)pair.first;
-        size_t numFrames = 0;
-        do {
-            const size_t frameCount = std::min((size_t)BLOCKSIZE, mFrameCount - numFrames);
-            memset(outTemp, 0, sizeof(outTemp));
-            for (const int name : group) {
-                const std::shared_ptr<Track> &t = mTracks[name];
-                int32_t *aux = NULL;
-                if (CC_UNLIKELY(t->needs & NEEDS_AUX)) {
-                    aux = t->auxBuffer + numFrames;
-                }
-                for (int outFrames = frameCount; outFrames > 0; ) {
-                    // t->in == nullptr can happen if the track was flushed just after having
-                    // been enabled for mixing.
-                    if (t->mIn == nullptr) {
-                        break;
-                    }
-                    size_t inFrames = (t->frameCount > outFrames)?outFrames:t->frameCount;
-                    if (inFrames > 0) {
-                        (t.get()->*t->hook)(
-                                outTemp + (frameCount - outFrames) * t->mMixerChannelCount,
-                                inFrames, mResampleTemp.get() /* naked ptr */, aux);
-                        t->frameCount -= inFrames;
-                        outFrames -= inFrames;
-                        if (CC_UNLIKELY(aux != NULL)) {
-                            aux += inFrames;
-                        }
-                    }
-                    if (t->frameCount == 0 && outFrames) {
-                        t->bufferProvider->releaseBuffer(&t->buffer);
-                        t->buffer.frameCount = (mFrameCount - numFrames) -
-                                (frameCount - outFrames);
-                        t->bufferProvider->getNextBuffer(&t->buffer);
-                        t->mIn = t->buffer.raw;
-                        if (t->mIn == nullptr) {
-                            break;
-                        }
-                        t->frameCount = t->buffer.frameCount;
-                    }
-                }
-            }
-
-            const std::shared_ptr<Track> &t1 = mTracks[group[0]];
-            convertMixerFormat(out, t1->mMixerFormat, outTemp, t1->mMixerInFormat,
-                    frameCount * t1->mMixerChannelCount);
-            // TODO: fix ugly casting due to choice of out pointer type
-            out = reinterpret_cast<int32_t*>((uint8_t*)out
-                    + frameCount * t1->mMixerChannelCount
-                    * audio_bytes_per_sample(t1->mMixerFormat));
-            numFrames += frameCount;
-        } while (numFrames < mFrameCount);
-
-        // release each track's buffer
-        for (const int name : group) {
-            const std::shared_ptr<Track> &t = mTracks[name];
-            t->bufferProvider->releaseBuffer(&t->buffer);
-        }
-    }
-}
-
-// generic code with resampling
-void AudioMixer::process__genericResampling()
-{
-    ALOGVV("process__genericResampling\n");
-    int32_t * const outTemp = mOutputTemp.get(); // naked ptr
-    size_t numFrames = mFrameCount;
-
-    for (const auto &pair : mGroups) {
-        const auto &group = pair.second;
-        const std::shared_ptr<Track> &t1 = mTracks[group[0]];
-
-        // clear temp buffer
-        memset(outTemp, 0, sizeof(*outTemp) * t1->mMixerChannelCount * mFrameCount);
-        for (const int name : group) {
-            const std::shared_ptr<Track> &t = mTracks[name];
-            int32_t *aux = NULL;
-            if (CC_UNLIKELY(t->needs & NEEDS_AUX)) {
-                aux = t->auxBuffer;
-            }
-
-            // this is a little goofy, on the resampling case we don't
-            // acquire/release the buffers because it's done by
-            // the resampler.
-            if (t->needs & NEEDS_RESAMPLE) {
-                (t.get()->*t->hook)(outTemp, numFrames, mResampleTemp.get() /* naked ptr */, aux);
-            } else {
-
-                size_t outFrames = 0;
-
-                while (outFrames < numFrames) {
-                    t->buffer.frameCount = numFrames - outFrames;
-                    t->bufferProvider->getNextBuffer(&t->buffer);
-                    t->mIn = t->buffer.raw;
-                    // t->mIn == nullptr can happen if the track was flushed just after having
-                    // been enabled for mixing.
-                    if (t->mIn == nullptr) break;
-
-                    (t.get()->*t->hook)(
-                            outTemp + outFrames * t->mMixerChannelCount, t->buffer.frameCount,
-                            mResampleTemp.get() /* naked ptr */,
-                            aux != nullptr ? aux + outFrames : nullptr);
-                    outFrames += t->buffer.frameCount;
-
-                    t->bufferProvider->releaseBuffer(&t->buffer);
-                }
-            }
-        }
-        convertMixerFormat(t1->mainBuffer, t1->mMixerFormat,
-                outTemp, t1->mMixerInFormat, numFrames * t1->mMixerChannelCount);
-    }
-}
-
-// one track, 16 bits stereo without resampling is the most common case
-void AudioMixer::process__oneTrack16BitsStereoNoResampling()
-{
-    ALOGVV("process__oneTrack16BitsStereoNoResampling\n");
-    LOG_ALWAYS_FATAL_IF(mEnabled.size() != 0,
-            "%zu != 1 tracks enabled", mEnabled.size());
-    const int name = mEnabled[0];
-    const std::shared_ptr<Track> &t = mTracks[name];
-
-    AudioBufferProvider::Buffer& b(t->buffer);
-
-    int32_t* out = t->mainBuffer;
-    float *fout = reinterpret_cast<float*>(out);
-    size_t numFrames = mFrameCount;
-
-    const int16_t vl = t->volume[0];
-    const int16_t vr = t->volume[1];
-    const uint32_t vrl = t->volumeRL;
-    while (numFrames) {
-        b.frameCount = numFrames;
-        t->bufferProvider->getNextBuffer(&b);
-        const int16_t *in = b.i16;
-
-        // in == NULL can happen if the track was flushed just after having
-        // been enabled for mixing.
-        if (in == NULL || (((uintptr_t)in) & 3)) {
-            if ( AUDIO_FORMAT_PCM_FLOAT == t->mMixerFormat ) {
-                 memset((char*)fout, 0, numFrames
-                         * t->mMixerChannelCount * audio_bytes_per_sample(t->mMixerFormat));
-            } else {
-                 memset((char*)out, 0, numFrames
-                         * t->mMixerChannelCount * audio_bytes_per_sample(t->mMixerFormat));
-            }
-            ALOGE_IF((((uintptr_t)in) & 3),
-                    "process__oneTrack16BitsStereoNoResampling: misaligned buffer"
-                    " %p track %d, channels %d, needs %08x, volume %08x vfl %f vfr %f",
-                    in, name, t->channelCount, t->needs, vrl, t->mVolume[0], t->mVolume[1]);
-            return;
-        }
-        size_t outFrames = b.frameCount;
-
-        switch (t->mMixerFormat) {
-        case AUDIO_FORMAT_PCM_FLOAT:
-            do {
-                uint32_t rl = *reinterpret_cast<const uint32_t *>(in);
-                in += 2;
-                int32_t l = mulRL(1, rl, vrl);
-                int32_t r = mulRL(0, rl, vrl);
-                *fout++ = float_from_q4_27(l);
-                *fout++ = float_from_q4_27(r);
-                // Note: In case of later int16_t sink output,
-                // conversion and clamping is done by memcpy_to_i16_from_float().
-            } while (--outFrames);
-            break;
-        case AUDIO_FORMAT_PCM_16_BIT:
-            if (CC_UNLIKELY(uint32_t(vl) > UNITY_GAIN_INT || uint32_t(vr) > UNITY_GAIN_INT)) {
-                // volume is boosted, so we might need to clamp even though
-                // we process only one track.
-                do {
-                    uint32_t rl = *reinterpret_cast<const uint32_t *>(in);
-                    in += 2;
-                    int32_t l = mulRL(1, rl, vrl) >> 12;
-                    int32_t r = mulRL(0, rl, vrl) >> 12;
-                    // clamping...
-                    l = clamp16(l);
-                    r = clamp16(r);
-                    *out++ = (r<<16) | (l & 0xFFFF);
-                } while (--outFrames);
-            } else {
-                do {
-                    uint32_t rl = *reinterpret_cast<const uint32_t *>(in);
-                    in += 2;
-                    int32_t l = mulRL(1, rl, vrl) >> 12;
-                    int32_t r = mulRL(0, rl, vrl) >> 12;
-                    *out++ = (r<<16) | (l & 0xFFFF);
-                } while (--outFrames);
-            }
-            break;
-        default:
-            LOG_ALWAYS_FATAL("bad mixer format: %d", t->mMixerFormat);
-        }
-        numFrames -= b.frameCount;
-        t->bufferProvider->releaseBuffer(&b);
-    }
-}
-
 /*static*/ pthread_once_t AudioMixer::sOnceControl = PTHREAD_ONCE_INIT;
 
 /*static*/ void AudioMixer::sInitRoutine()
@@ -1664,211 +523,71 @@
     DownmixerBufferProvider::init(); // for the downmixer
 }
 
-/* TODO: consider whether this level of optimization is necessary.
- * Perhaps just stick with a single for loop.
- */
-
-// Needs to derive a compile time constant (constexpr).  Could be targeted to go
-// to a MONOVOL mixtype based on MAX_NUM_VOLUMES, but that's an unnecessary complication.
-#define MIXTYPE_MONOVOL(mixtype) ((mixtype) == MIXTYPE_MULTI ? MIXTYPE_MULTI_MONOVOL : \
-        (mixtype) == MIXTYPE_MULTI_SAVEONLY ? MIXTYPE_MULTI_SAVEONLY_MONOVOL : (mixtype))
-
-/* MIXTYPE     (see AudioMixerOps.h MIXTYPE_* enumeration)
- * TO: int32_t (Q4.27) or float
- * TI: int32_t (Q4.27) or int16_t (Q0.15) or float
- * TA: int32_t (Q4.27) or float
- */
-template <int MIXTYPE,
-        typename TO, typename TI, typename TV, typename TA, typename TAV>
-static void volumeRampMulti(uint32_t channels, TO* out, size_t frameCount,
-        const TI* in, TA* aux, TV *vol, const TV *volinc, TAV *vola, TAV volainc)
+std::shared_ptr<AudioMixerBase::TrackBase> AudioMixer::preCreateTrack()
 {
-    switch (channels) {
-    case 1:
-        volumeRampMulti<MIXTYPE, 1>(out, frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 2:
-        volumeRampMulti<MIXTYPE, 2>(out, frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 3:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 3>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 4:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 4>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 5:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 5>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 6:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 6>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 7:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 7>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 8:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 8>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    }
+    return std::make_shared<Track>();
 }
 
-/* MIXTYPE     (see AudioMixerOps.h MIXTYPE_* enumeration)
- * TO: int32_t (Q4.27) or float
- * TI: int32_t (Q4.27) or int16_t (Q0.15) or float
- * TA: int32_t (Q4.27) or float
- */
-template <int MIXTYPE,
-        typename TO, typename TI, typename TV, typename TA, typename TAV>
-static void volumeMulti(uint32_t channels, TO* out, size_t frameCount,
-        const TI* in, TA* aux, const TV *vol, TAV vola)
+status_t AudioMixer::postCreateTrack(TrackBase *track)
 {
-    switch (channels) {
-    case 1:
-        volumeMulti<MIXTYPE, 1>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 2:
-        volumeMulti<MIXTYPE, 2>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 3:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 3>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 4:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 4>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 5:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 5>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 6:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 6>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 7:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 7>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 8:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 8>(out, frameCount, in, aux, vol, vola);
-        break;
+    Track* t = static_cast<Track*>(track);
+
+    audio_channel_mask_t channelMask = t->channelMask;
+    t->mHapticChannelMask = channelMask & AUDIO_CHANNEL_HAPTIC_ALL;
+    t->mHapticChannelCount = audio_channel_count_from_out_mask(t->mHapticChannelMask);
+    channelMask &= ~AUDIO_CHANNEL_HAPTIC_ALL;
+    t->channelCount = audio_channel_count_from_out_mask(channelMask);
+    ALOGV_IF(audio_channel_mask_get_bits(channelMask) != AUDIO_CHANNEL_OUT_STEREO,
+            "Non-stereo channel mask: %d\n", channelMask);
+    t->channelMask = channelMask;
+    t->mInputBufferProvider = NULL;
+    t->mDownmixRequiresFormat = AUDIO_FORMAT_INVALID; // no format required
+    t->mPlaybackRate = AUDIO_PLAYBACK_RATE_DEFAULT;
+    // haptic
+    t->mHapticPlaybackEnabled = false;
+    t->mHapticIntensity = HAPTIC_SCALE_NONE;
+    t->mMixerHapticChannelMask = AUDIO_CHANNEL_NONE;
+    t->mMixerHapticChannelCount = 0;
+    t->mAdjustInChannelCount = t->channelCount + t->mHapticChannelCount;
+    t->mAdjustOutChannelCount = t->channelCount + t->mMixerHapticChannelCount;
+    t->mAdjustNonDestructiveInChannelCount = t->mAdjustOutChannelCount;
+    t->mAdjustNonDestructiveOutChannelCount = t->channelCount;
+    t->mKeepContractedChannels = false;
+    // Check the downmixing (or upmixing) requirements.
+    status_t status = t->prepareForDownmix();
+    if (status != OK) {
+        ALOGE("AudioMixer::getTrackName invalid channelMask (%#x)", channelMask);
+        return BAD_VALUE;
     }
+    // prepareForDownmix() may change mDownmixRequiresFormat
+    ALOGVV("mMixerFormat:%#x  mMixerInFormat:%#x\n", t->mMixerFormat, t->mMixerInFormat);
+    t->prepareForReformat();
+    t->prepareForAdjustChannelsNonDestructive(mFrameCount);
+    t->prepareForAdjustChannels();
+    return OK;
 }
 
-/* MIXTYPE     (see AudioMixerOps.h MIXTYPE_* enumeration)
- * USEFLOATVOL (set to true if float volume is used)
- * ADJUSTVOL   (set to true if volume ramp parameters needs adjustment afterwards)
- * TO: int32_t (Q4.27) or float
- * TI: int32_t (Q4.27) or int16_t (Q0.15) or float
- * TA: int32_t (Q4.27) or float
- */
-template <int MIXTYPE, bool USEFLOATVOL, bool ADJUSTVOL,
-    typename TO, typename TI, typename TA>
-void AudioMixer::Track::volumeMix(TO *out, size_t outFrames,
-        const TI *in, TA *aux, bool ramp)
+void AudioMixer::preProcess()
 {
-    if (USEFLOATVOL) {
-        if (ramp) {
-            volumeRampMulti<MIXTYPE>(mMixerChannelCount, out, outFrames, in, aux,
-                    mPrevVolume, mVolumeInc,
-#ifdef FLOAT_AUX
-                    &mPrevAuxLevel, mAuxInc
-#else
-                    &prevAuxLevel, auxInc
-#endif
-                );
-            if (ADJUSTVOL) {
-                adjustVolumeRamp(aux != NULL, true);
-            }
-        } else {
-            volumeMulti<MIXTYPE>(mMixerChannelCount, out, outFrames, in, aux,
-                    mVolume,
-#ifdef FLOAT_AUX
-                    mAuxLevel
-#else
-                    auxLevel
-#endif
-            );
-        }
-    } else {
-        if (ramp) {
-            volumeRampMulti<MIXTYPE>(mMixerChannelCount, out, outFrames, in, aux,
-                    prevVolume, volumeInc, &prevAuxLevel, auxInc);
-            if (ADJUSTVOL) {
-                adjustVolumeRamp(aux != NULL);
-            }
-        } else {
-            volumeMulti<MIXTYPE>(mMixerChannelCount, out, outFrames, in, aux,
-                    volume, auxLevel);
+    for (const auto &pair : mTracks) {
+        // Clear contracted buffer before processing if contracted channels are saved
+        const std::shared_ptr<TrackBase> &tb = pair.second;
+        Track *t = static_cast<Track*>(tb.get());
+        if (t->mKeepContractedChannels) {
+            t->clearContractedBuffer();
         }
     }
 }
 
-/* This process hook is called when there is a single track without
- * aux buffer, volume ramp, or resampling.
- * TODO: Update the hook selection: this can properly handle aux and ramp.
- *
- * MIXTYPE     (see AudioMixerOps.h MIXTYPE_* enumeration)
- * TO: int32_t (Q4.27) or float
- * TI: int32_t (Q4.27) or int16_t (Q0.15) or float
- * TA: int32_t (Q4.27)
- */
-template <int MIXTYPE, typename TO, typename TI, typename TA>
-void AudioMixer::process__noResampleOneTrack()
+void AudioMixer::postProcess()
 {
-    ALOGVV("process__noResampleOneTrack\n");
-    LOG_ALWAYS_FATAL_IF(mEnabled.size() != 1,
-            "%zu != 1 tracks enabled", mEnabled.size());
-    const std::shared_ptr<Track> &t = mTracks[mEnabled[0]];
-    const uint32_t channels = t->mMixerChannelCount;
-    TO* out = reinterpret_cast<TO*>(t->mainBuffer);
-    TA* aux = reinterpret_cast<TA*>(t->auxBuffer);
-    const bool ramp = t->needsRamp();
-
-    for (size_t numFrames = mFrameCount; numFrames > 0; ) {
-        AudioBufferProvider::Buffer& b(t->buffer);
-        // get input buffer
-        b.frameCount = numFrames;
-        t->bufferProvider->getNextBuffer(&b);
-        const TI *in = reinterpret_cast<TI*>(b.raw);
-
-        // in == NULL can happen if the track was flushed just after having
-        // been enabled for mixing.
-        if (in == NULL || (((uintptr_t)in) & 3)) {
-            memset(out, 0, numFrames
-                    * channels * audio_bytes_per_sample(t->mMixerFormat));
-            ALOGE_IF((((uintptr_t)in) & 3), "process__noResampleOneTrack: bus error: "
-                    "buffer %p track %p, channels %d, needs %#x",
-                    in, &t, t->channelCount, t->needs);
-            return;
-        }
-
-        const size_t outFrames = b.frameCount;
-        t->volumeMix<MIXTYPE, is_same<TI, float>::value /* USEFLOATVOL */, false /* ADJUSTVOL */> (
-                out, outFrames, in, aux, ramp);
-
-        out += outFrames * channels;
-        if (aux != NULL) {
-            aux += outFrames;
-        }
-        numFrames -= b.frameCount;
-
-        // release buffer
-        t->bufferProvider->releaseBuffer(&b);
-    }
-    if (ramp) {
-        t->adjustVolumeRamp(aux != NULL, is_same<TI, float>::value);
-    }
-}
-
-void AudioMixer::processHapticData()
-{
+    // Process haptic data.
     // Need to keep consistent with VibrationEffect.scale(int, float, int)
     for (const auto &pair : mGroups) {
         // process by group of tracks with same output main buffer.
         const auto &group = pair.second;
         for (const int name : group) {
-            const std::shared_ptr<Track> &t = mTracks[name];
+            const std::shared_ptr<Track> &t = getTrack(name);
             if (t->mHapticPlaybackEnabled) {
                 size_t sampleCount = mFrameCount * t->mMixerHapticChannelCount;
                 float gamma = t->getHapticScaleGamma();
@@ -1895,225 +614,5 @@
     }
 }
 
-/* This track hook is called to do resampling then mixing,
- * pulling from the track's upstream AudioBufferProvider.
- *
- * MIXTYPE     (see AudioMixerOps.h MIXTYPE_* enumeration)
- * TO: int32_t (Q4.27) or float
- * TI: int32_t (Q4.27) or int16_t (Q0.15) or float
- * TA: int32_t (Q4.27) or float
- */
-template <int MIXTYPE, typename TO, typename TI, typename TA>
-void AudioMixer::Track::track__Resample(TO* out, size_t outFrameCount, TO* temp, TA* aux)
-{
-    ALOGVV("track__Resample\n");
-    mResampler->setSampleRate(sampleRate);
-    const bool ramp = needsRamp();
-    if (ramp || aux != NULL) {
-        // if ramp:        resample with unity gain to temp buffer and scale/mix in 2nd step.
-        // if aux != NULL: resample with unity gain to temp buffer then apply send level.
-
-        mResampler->setVolume(UNITY_GAIN_FLOAT, UNITY_GAIN_FLOAT);
-        memset(temp, 0, outFrameCount * mMixerChannelCount * sizeof(TO));
-        mResampler->resample((int32_t*)temp, outFrameCount, bufferProvider);
-
-        volumeMix<MIXTYPE, is_same<TI, float>::value /* USEFLOATVOL */, true /* ADJUSTVOL */>(
-                out, outFrameCount, temp, aux, ramp);
-
-    } else { // constant volume gain
-        mResampler->setVolume(mVolume[0], mVolume[1]);
-        mResampler->resample((int32_t*)out, outFrameCount, bufferProvider);
-    }
-}
-
-/* This track hook is called to mix a track, when no resampling is required.
- * The input buffer should be present in in.
- *
- * MIXTYPE     (see AudioMixerOps.h MIXTYPE_* enumeration)
- * TO: int32_t (Q4.27) or float
- * TI: int32_t (Q4.27) or int16_t (Q0.15) or float
- * TA: int32_t (Q4.27) or float
- */
-template <int MIXTYPE, typename TO, typename TI, typename TA>
-void AudioMixer::Track::track__NoResample(TO* out, size_t frameCount, TO* temp __unused, TA* aux)
-{
-    ALOGVV("track__NoResample\n");
-    const TI *in = static_cast<const TI *>(mIn);
-
-    volumeMix<MIXTYPE, is_same<TI, float>::value /* USEFLOATVOL */, true /* ADJUSTVOL */>(
-            out, frameCount, in, aux, needsRamp());
-
-    // MIXTYPE_MONOEXPAND reads a single input channel and expands to NCHAN output channels.
-    // MIXTYPE_MULTI reads NCHAN input channels and places to NCHAN output channels.
-    in += (MIXTYPE == MIXTYPE_MONOEXPAND) ? frameCount : frameCount * mMixerChannelCount;
-    mIn = in;
-}
-
-/* The Mixer engine generates either int32_t (Q4_27) or float data.
- * We use this function to convert the engine buffers
- * to the desired mixer output format, either int16_t (Q.15) or float.
- */
-/* static */
-void AudioMixer::convertMixerFormat(void *out, audio_format_t mixerOutFormat,
-        void *in, audio_format_t mixerInFormat, size_t sampleCount)
-{
-    switch (mixerInFormat) {
-    case AUDIO_FORMAT_PCM_FLOAT:
-        switch (mixerOutFormat) {
-        case AUDIO_FORMAT_PCM_FLOAT:
-            memcpy(out, in, sampleCount * sizeof(float)); // MEMCPY. TODO optimize out
-            break;
-        case AUDIO_FORMAT_PCM_16_BIT:
-            memcpy_to_i16_from_float((int16_t*)out, (float*)in, sampleCount);
-            break;
-        default:
-            LOG_ALWAYS_FATAL("bad mixerOutFormat: %#x", mixerOutFormat);
-            break;
-        }
-        break;
-    case AUDIO_FORMAT_PCM_16_BIT:
-        switch (mixerOutFormat) {
-        case AUDIO_FORMAT_PCM_FLOAT:
-            memcpy_to_float_from_q4_27((float*)out, (const int32_t*)in, sampleCount);
-            break;
-        case AUDIO_FORMAT_PCM_16_BIT:
-            memcpy_to_i16_from_q4_27((int16_t*)out, (const int32_t*)in, sampleCount);
-            break;
-        default:
-            LOG_ALWAYS_FATAL("bad mixerOutFormat: %#x", mixerOutFormat);
-            break;
-        }
-        break;
-    default:
-        LOG_ALWAYS_FATAL("bad mixerInFormat: %#x", mixerInFormat);
-        break;
-    }
-}
-
-/* Returns the proper track hook to use for mixing the track into the output buffer.
- */
-/* static */
-AudioMixer::hook_t AudioMixer::Track::getTrackHook(int trackType, uint32_t channelCount,
-        audio_format_t mixerInFormat, audio_format_t mixerOutFormat __unused)
-{
-    if (!kUseNewMixer && channelCount == FCC_2 && mixerInFormat == AUDIO_FORMAT_PCM_16_BIT) {
-        switch (trackType) {
-        case TRACKTYPE_NOP:
-            return &Track::track__nop;
-        case TRACKTYPE_RESAMPLE:
-            return &Track::track__genericResample;
-        case TRACKTYPE_NORESAMPLEMONO:
-            return &Track::track__16BitsMono;
-        case TRACKTYPE_NORESAMPLE:
-            return &Track::track__16BitsStereo;
-        default:
-            LOG_ALWAYS_FATAL("bad trackType: %d", trackType);
-            break;
-        }
-    }
-    LOG_ALWAYS_FATAL_IF(channelCount > MAX_NUM_CHANNELS);
-    switch (trackType) {
-    case TRACKTYPE_NOP:
-        return &Track::track__nop;
-    case TRACKTYPE_RESAMPLE:
-        switch (mixerInFormat) {
-        case AUDIO_FORMAT_PCM_FLOAT:
-            return (AudioMixer::hook_t) &Track::track__Resample<
-                    MIXTYPE_MULTI, float /*TO*/, float /*TI*/, TYPE_AUX>;
-        case AUDIO_FORMAT_PCM_16_BIT:
-            return (AudioMixer::hook_t) &Track::track__Resample<
-                    MIXTYPE_MULTI, int32_t /*TO*/, int16_t /*TI*/, TYPE_AUX>;
-        default:
-            LOG_ALWAYS_FATAL("bad mixerInFormat: %#x", mixerInFormat);
-            break;
-        }
-        break;
-    case TRACKTYPE_NORESAMPLEMONO:
-        switch (mixerInFormat) {
-        case AUDIO_FORMAT_PCM_FLOAT:
-            return (AudioMixer::hook_t) &Track::track__NoResample<
-                            MIXTYPE_MONOEXPAND, float /*TO*/, float /*TI*/, TYPE_AUX>;
-        case AUDIO_FORMAT_PCM_16_BIT:
-            return (AudioMixer::hook_t) &Track::track__NoResample<
-                            MIXTYPE_MONOEXPAND, int32_t /*TO*/, int16_t /*TI*/, TYPE_AUX>;
-        default:
-            LOG_ALWAYS_FATAL("bad mixerInFormat: %#x", mixerInFormat);
-            break;
-        }
-        break;
-    case TRACKTYPE_NORESAMPLE:
-        switch (mixerInFormat) {
-        case AUDIO_FORMAT_PCM_FLOAT:
-            return (AudioMixer::hook_t) &Track::track__NoResample<
-                    MIXTYPE_MULTI, float /*TO*/, float /*TI*/, TYPE_AUX>;
-        case AUDIO_FORMAT_PCM_16_BIT:
-            return (AudioMixer::hook_t) &Track::track__NoResample<
-                    MIXTYPE_MULTI, int32_t /*TO*/, int16_t /*TI*/, TYPE_AUX>;
-        default:
-            LOG_ALWAYS_FATAL("bad mixerInFormat: %#x", mixerInFormat);
-            break;
-        }
-        break;
-    default:
-        LOG_ALWAYS_FATAL("bad trackType: %d", trackType);
-        break;
-    }
-    return NULL;
-}
-
-/* Returns the proper process hook for mixing tracks. Currently works only for
- * PROCESSTYPE_NORESAMPLEONETRACK, a mix involving one track, no resampling.
- *
- * TODO: Due to the special mixing considerations of duplicating to
- * a stereo output track, the input track cannot be MONO.  This should be
- * prevented by the caller.
- */
-/* static */
-AudioMixer::process_hook_t AudioMixer::getProcessHook(
-        int processType, uint32_t channelCount,
-        audio_format_t mixerInFormat, audio_format_t mixerOutFormat)
-{
-    if (processType != PROCESSTYPE_NORESAMPLEONETRACK) { // Only NORESAMPLEONETRACK
-        LOG_ALWAYS_FATAL("bad processType: %d", processType);
-        return NULL;
-    }
-    if (!kUseNewMixer && channelCount == FCC_2 && mixerInFormat == AUDIO_FORMAT_PCM_16_BIT) {
-        return &AudioMixer::process__oneTrack16BitsStereoNoResampling;
-    }
-    LOG_ALWAYS_FATAL_IF(channelCount > MAX_NUM_CHANNELS);
-    switch (mixerInFormat) {
-    case AUDIO_FORMAT_PCM_FLOAT:
-        switch (mixerOutFormat) {
-        case AUDIO_FORMAT_PCM_FLOAT:
-            return &AudioMixer::process__noResampleOneTrack<
-                    MIXTYPE_MULTI_SAVEONLY, float /*TO*/, float /*TI*/, TYPE_AUX>;
-        case AUDIO_FORMAT_PCM_16_BIT:
-            return &AudioMixer::process__noResampleOneTrack<
-                    MIXTYPE_MULTI_SAVEONLY, int16_t /*TO*/, float /*TI*/, TYPE_AUX>;
-        default:
-            LOG_ALWAYS_FATAL("bad mixerOutFormat: %#x", mixerOutFormat);
-            break;
-        }
-        break;
-    case AUDIO_FORMAT_PCM_16_BIT:
-        switch (mixerOutFormat) {
-        case AUDIO_FORMAT_PCM_FLOAT:
-            return &AudioMixer::process__noResampleOneTrack<
-                    MIXTYPE_MULTI_SAVEONLY, float /*TO*/, int16_t /*TI*/, TYPE_AUX>;
-        case AUDIO_FORMAT_PCM_16_BIT:
-            return &AudioMixer::process__noResampleOneTrack<
-                    MIXTYPE_MULTI_SAVEONLY, int16_t /*TO*/, int16_t /*TI*/, TYPE_AUX>;
-        default:
-            LOG_ALWAYS_FATAL("bad mixerOutFormat: %#x", mixerOutFormat);
-            break;
-        }
-        break;
-    default:
-        LOG_ALWAYS_FATAL("bad mixerInFormat: %#x", mixerInFormat);
-        break;
-    }
-    return NULL;
-}
-
 // ----------------------------------------------------------------------------
 } // namespace android