xref: /frameworks/av/media/libstagefright/MediaCodecSource.cpp

/*
 * Copyright 2014, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//#define LOG_NDEBUG 0
#define LOG_TAG "MediaCodecSource"
#define DEBUG_DRIFT_TIME 0

#include <inttypes.h>

#include <gui/IGraphicBufferConsumer.h>
#include <gui/IGraphicBufferProducer.h>
#include <gui/Surface.h>
#include <media/ICrypto.h>
#include <media/stagefright/foundation/ABuffer.h>
#include <media/stagefright/foundation/ADebug.h>
#include <media/stagefright/foundation/ALooper.h>
#include <media/stagefright/foundation/AMessage.h>
#include <media/stagefright/MediaBuffer.h>
#include <media/stagefright/MediaCodec.h>
#include <media/stagefright/MediaCodecList.h>
#include <media/stagefright/MediaCodecSource.h>
#include <media/stagefright/MediaErrors.h>
#include <media/stagefright/MediaSource.h>
#include <media/stagefright/MetaData.h>
#include <media/stagefright/PersistentSurface.h>
#include <media/stagefright/Utils.h>

namespace android {

const int kDefaultSwVideoEncoderFormat = HAL_PIXEL_FORMAT_YCbCr_420_888;
const int kDefaultSwVideoEncoderDataSpace = HAL_DATASPACE_BT709;

const int kStopTimeoutUs = 300000; // allow 1 sec for shutting down encoder

struct MediaCodecSource::Puller : public AHandler {
    Puller(const sp<MediaSource> &source);

    void interruptSource();
    status_t start(const sp<MetaData> &meta, const sp<AMessage> &notify);
    void stop();
    void stopSource();
    void pause();
    void resume();

    bool readBuffer(MediaBuffer **buffer);

protected:
    virtual void onMessageReceived(const sp<AMessage> &msg);
    virtual ~Puller();

private:
    enum {
        kWhatStart = 'msta',
        kWhatStop,
        kWhatPull,
    };

    sp<MediaSource> mSource;
    sp<AMessage> mNotify;
    sp<ALooper> mLooper;
    bool mIsAudio;

    struct Queue {
        Queue()
            : mReadPendingSince(0),
              mPaused(false),
              mPulling(false) { }
        int64_t mReadPendingSince;
        bool mPaused;
        bool mPulling;
        Vector<MediaBuffer *> mReadBuffers;

        void flush();
        // if queue is empty, return false and set *|buffer| to NULL . Otherwise, pop
        // buffer from front of the queue, place it into *|buffer| and return true.
        bool readBuffer(MediaBuffer **buffer);
        // add a buffer to the back of the queue
        void pushBuffer(MediaBuffer *mbuf);
    };
    Mutexed<Queue> mQueue;

    status_t postSynchronouslyAndReturnError(const sp<AMessage> &msg);
    void schedulePull();
    void handleEOS();

    DISALLOW_EVIL_CONSTRUCTORS(Puller);
};

MediaCodecSource::Puller::Puller(const sp<MediaSource> &source)
    : mSource(source),
      mLooper(new ALooper()),
      mIsAudio(false)
{
    sp<MetaData> meta = source->getFormat();
    const char *mime;
    CHECK(meta->findCString(kKeyMIMEType, &mime));

    mIsAudio = !strncasecmp(mime, "audio/", 6);

    mLooper->setName("pull_looper");
}

MediaCodecSource::Puller::~Puller() {
    mLooper->unregisterHandler(id());
    mLooper->stop();
}

void MediaCodecSource::Puller::Queue::pushBuffer(MediaBuffer *mbuf) {
    mReadBuffers.push_back(mbuf);
}

bool MediaCodecSource::Puller::Queue::readBuffer(MediaBuffer **mbuf) {
    if (mReadBuffers.empty()) {
        *mbuf = NULL;
        return false;
    }
    *mbuf = *mReadBuffers.begin();
    mReadBuffers.erase(mReadBuffers.begin());
    return true;
}

void MediaCodecSource::Puller::Queue::flush() {
    MediaBuffer *mbuf;
    while (readBuffer(&mbuf)) {
        // there are no null buffers in the queue
        mbuf->release();
    }
}

bool MediaCodecSource::Puller::readBuffer(MediaBuffer **mbuf) {
    Mutexed<Queue>::Locked queue(mQueue);
    return queue->readBuffer(mbuf);
}

status_t MediaCodecSource::Puller::postSynchronouslyAndReturnError(
        const sp<AMessage> &msg) {
    sp<AMessage> response;
    status_t err = msg->postAndAwaitResponse(&response);

    if (err != OK) {
        return err;
    }

    if (!response->findInt32("err", &err)) {
        err = OK;
    }

    return err;
}

status_t MediaCodecSource::Puller::start(const sp<MetaData> &meta, const sp<AMessage> &notify) {
    ALOGV("puller (%s) start", mIsAudio ? "audio" : "video");
    mLooper->start(
            false /* runOnCallingThread */,
            false /* canCallJava */,
            PRIORITY_AUDIO);
    mLooper->registerHandler(this);
    mNotify = notify;

    sp<AMessage> msg = new AMessage(kWhatStart, this);
    msg->setObject("meta", meta);
    return postSynchronouslyAndReturnError(msg);
}

void MediaCodecSource::Puller::stop() {
    bool interrupt = false;
    {
        // mark stopping before actually reaching kWhatStop on the looper, so the pulling will
        // stop.
        Mutexed<Queue>::Locked queue(mQueue);
        queue->mPulling = false;
        interrupt = queue->mReadPendingSince && (queue->mReadPendingSince < ALooper::GetNowUs() - 1000000);
        queue->flush(); // flush any unprocessed pulled buffers
    }

    if (interrupt) {
        interruptSource();
    }
}

void MediaCodecSource::Puller::interruptSource() {
    // call source->stop if read has been pending for over a second
    // We have to call this outside the looper as looper is pending on the read.
    mSource->stop();
}

void MediaCodecSource::Puller::stopSource() {
    sp<AMessage> msg = new AMessage(kWhatStop, this);
    (void)postSynchronouslyAndReturnError(msg);
}

void MediaCodecSource::Puller::pause() {
    Mutexed<Queue>::Locked queue(mQueue);
    queue->mPaused = true;
}

void MediaCodecSource::Puller::resume() {
    Mutexed<Queue>::Locked queue(mQueue);
    queue->mPaused = false;
}

void MediaCodecSource::Puller::schedulePull() {
    (new AMessage(kWhatPull, this))->post();
}

void MediaCodecSource::Puller::handleEOS() {
    ALOGV("puller (%s) posting EOS", mIsAudio ? "audio" : "video");
    sp<AMessage> msg = mNotify->dup();
    msg->setInt32("eos", 1);
    msg->post();
}

void MediaCodecSource::Puller::onMessageReceived(const sp<AMessage> &msg) {
    switch (msg->what()) {
        case kWhatStart:
        {
            sp<RefBase> obj;
            CHECK(msg->findObject("meta", &obj));

            {
                Mutexed<Queue>::Locked queue(mQueue);
                queue->mPulling = true;
            }

            status_t err = mSource->start(static_cast<MetaData *>(obj.get()));

            if (err == OK) {
                schedulePull();
            }

            sp<AMessage> response = new AMessage;
            response->setInt32("err", err);

            sp<AReplyToken> replyID;
            CHECK(msg->senderAwaitsResponse(&replyID));
            response->postReply(replyID);
            break;
        }

        case kWhatStop:
        {
            mSource->stop();

            sp<AMessage> response = new AMessage;
            response->setInt32("err", OK);

            sp<AReplyToken> replyID;
            CHECK(msg->senderAwaitsResponse(&replyID));
            response->postReply(replyID);
            break;
        }

        case kWhatPull:
        {
            Mutexed<Queue>::Locked queue(mQueue);
            queue->mReadPendingSince = ALooper::GetNowUs();
            if (!queue->mPulling) {
                handleEOS();
                break;
            }

            queue.unlock();
            MediaBuffer *mbuf = NULL;
            status_t err = mSource->read(&mbuf);
            queue.lock();

            queue->mReadPendingSince = 0;
            // if we need to discard buffer
            if (!queue->mPulling || queue->mPaused || err != OK) {
                if (mbuf != NULL) {
                    mbuf->release();
                    mbuf = NULL;
                }
                if (queue->mPulling && err == OK) {
                    msg->post(); // if simply paused, keep pulling source
                } else if (err == ERROR_END_OF_STREAM) {
                    ALOGV("stream ended, mbuf %p", mbuf);
                } else if (err != OK) {
                    ALOGE("error %d reading stream.", err);
                }
            }

            if (mbuf != NULL) {
                queue->pushBuffer(mbuf);
            }

            queue.unlock();

            if (mbuf != NULL) {
                mNotify->post();
                msg->post();
            } else {
                handleEOS();
            }
            break;
        }

        default:
            TRESPASS();
    }
}

MediaCodecSource::Output::Output()
    : mEncoderReachedEOS(false),
      mErrorCode(OK) {
}

// static
sp<MediaCodecSource> MediaCodecSource::Create(
        const sp<ALooper> &looper,
        const sp<AMessage> &format,
        const sp<MediaSource> &source,
        const sp<IGraphicBufferConsumer> &consumer,
        uint32_t flags) {
    sp<MediaCodecSource> mediaSource =
            new MediaCodecSource(looper, format, source, consumer, flags);

    if (mediaSource->init() == OK) {
        return mediaSource;
    }
    return NULL;
}

void MediaCodecSource::setInputBufferTimeOffset(int64_t timeOffsetUs) {
    sp<AMessage> msg = new AMessage(kWhatSetInputBufferTimeOffset, mReflector);
    msg->setInt64("time-offset-us", timeOffsetUs);
    postSynchronouslyAndReturnError(msg);
}

status_t MediaCodecSource::start(MetaData* params) {
    sp<AMessage> msg = new AMessage(kWhatStart, mReflector);
    msg->setObject("meta", params);
    return postSynchronouslyAndReturnError(msg);
}

status_t MediaCodecSource::stop() {
    sp<AMessage> msg = new AMessage(kWhatStop, mReflector);
    return postSynchronouslyAndReturnError(msg);
}

status_t MediaCodecSource::pause() {
    (new AMessage(kWhatPause, mReflector))->post();
    return OK;
}

sp<IGraphicBufferProducer> MediaCodecSource::getGraphicBufferProducer() {
    CHECK(mFlags & FLAG_USE_SURFACE_INPUT);
    return mGraphicBufferProducer;
}

status_t MediaCodecSource::read(
        MediaBuffer** buffer, const ReadOptions* /* options */) {
    Mutexed<Output>::Locked output(mOutput);

    *buffer = NULL;
    while (output->mBufferQueue.size() == 0 && !output->mEncoderReachedEOS) {
        output.waitForCondition(output->mCond);
    }
    if (!output->mEncoderReachedEOS) {
        *buffer = *output->mBufferQueue.begin();
        output->mBufferQueue.erase(output->mBufferQueue.begin());
        return OK;
    }
    return output->mErrorCode;
}

void MediaCodecSource::signalBufferReturned(MediaBuffer *buffer) {
    buffer->setObserver(0);
    buffer->release();
}

MediaCodecSource::MediaCodecSource(
        const sp<ALooper> &looper,
        const sp<AMessage> &outputFormat,
        const sp<MediaSource> &source,
        const sp<IGraphicBufferConsumer> &consumer,
        uint32_t flags)
    : mLooper(looper),
      mOutputFormat(outputFormat),
      mMeta(new MetaData),
      mFlags(flags),
      mIsVideo(false),
      mStarted(false),
      mStopping(false),
      mDoMoreWorkPending(false),
      mSetEncoderFormat(false),
      mEncoderFormat(0),
      mEncoderDataSpace(0),
      mGraphicBufferConsumer(consumer),
      mInputBufferTimeOffsetUs(0),
      mFirstSampleTimeUs(-1ll),
      mGeneration(0) {
    CHECK(mLooper != NULL);

    AString mime;
    CHECK(mOutputFormat->findString("mime", &mime));

    if (!strncasecmp("video/", mime.c_str(), 6)) {
        mIsVideo = true;
    }

    if (!(mFlags & FLAG_USE_SURFACE_INPUT)) {
        mPuller = new Puller(source);
    }
}

MediaCodecSource::~MediaCodecSource() {
    releaseEncoder();

    mCodecLooper->stop();
    mLooper->unregisterHandler(mReflector->id());
}

status_t MediaCodecSource::init() {
    status_t err = initEncoder();

    if (err != OK) {
        releaseEncoder();
    }

    return err;
}

status_t MediaCodecSource::initEncoder() {
    mReflector = new AHandlerReflector<MediaCodecSource>(this);
    mLooper->registerHandler(mReflector);

    mCodecLooper = new ALooper;
    mCodecLooper->setName("codec_looper");
    mCodecLooper->start();

    if (mFlags & FLAG_USE_METADATA_INPUT) {
        mOutputFormat->setInt32("store-metadata-in-buffers", 1);
    }

    if (mFlags & FLAG_USE_SURFACE_INPUT) {
        mOutputFormat->setInt32("create-input-buffers-suspended", 1);
    }

    AString outputMIME;
    CHECK(mOutputFormat->findString("mime", &outputMIME));

    Vector<AString> matchingCodecs;
    MediaCodecList::findMatchingCodecs(
            outputMIME.c_str(), true /* encoder */,
            ((mFlags & FLAG_PREFER_SOFTWARE_CODEC) ? MediaCodecList::kPreferSoftwareCodecs : 0),
            &matchingCodecs);

    status_t err = NO_INIT;
    for (size_t ix = 0; ix < matchingCodecs.size(); ++ix) {
        mEncoder = MediaCodec::CreateByComponentName(
                mCodecLooper, matchingCodecs[ix]);

        if (mEncoder == NULL) {
            continue;
        }

        ALOGV("output format is '%s'", mOutputFormat->debugString(0).c_str());

        mEncoderActivityNotify = new AMessage(kWhatEncoderActivity, mReflector);
        mEncoder->setCallback(mEncoderActivityNotify);

        err = mEncoder->configure(
                    mOutputFormat,
                    NULL /* nativeWindow */,
                    NULL /* crypto */,
                    MediaCodec::CONFIGURE_FLAG_ENCODE);

        if (err == OK) {
            break;
        }
        mEncoder->release();
        mEncoder = NULL;
    }

    if (err != OK) {
        return err;
    }

    mEncoder->getOutputFormat(&mOutputFormat);
    convertMessageToMetaData(mOutputFormat, mMeta);

    if (mFlags & FLAG_USE_SURFACE_INPUT) {
        CHECK(mIsVideo);

        if (mGraphicBufferConsumer != NULL) {
            // When using persistent surface, we are only interested in the
            // consumer, but have to use PersistentSurface as a wrapper to
            // pass consumer over messages (similar to BufferProducerWrapper)
            err = mEncoder->setInputSurface(
                    new PersistentSurface(NULL, mGraphicBufferConsumer));
        } else {
            err = mEncoder->createInputSurface(&mGraphicBufferProducer);
        }

        if (err != OK) {
            return err;
        }
    }

    sp<AMessage> inputFormat;
    int32_t usingSwReadOften;
    mSetEncoderFormat = false;
    if (mEncoder->getInputFormat(&inputFormat) == OK
            && inputFormat->findInt32("using-sw-read-often", &usingSwReadOften)
            && usingSwReadOften) {
        // this is a SW encoder; signal source to allocate SW readable buffers
        mSetEncoderFormat = true;
        mEncoderFormat = kDefaultSwVideoEncoderFormat;
        mEncoderDataSpace = kDefaultSwVideoEncoderDataSpace;
    }

    err = mEncoder->start();

    if (err != OK) {
        return err;
    }

    {
        Mutexed<Output>::Locked output(mOutput);
        output->mEncoderReachedEOS = false;
        output->mErrorCode = OK;
    }

    return OK;
}

void MediaCodecSource::releaseEncoder() {
    if (mEncoder == NULL) {
        return;
    }

    mEncoder->release();
    mEncoder.clear();
}

status_t MediaCodecSource::postSynchronouslyAndReturnError(
        const sp<AMessage> &msg) {
    sp<AMessage> response;
    status_t err = msg->postAndAwaitResponse(&response);

    if (err != OK) {
        return err;
    }

    if (!response->findInt32("err", &err)) {
        err = OK;
    }

    return err;
}

void MediaCodecSource::signalEOS(status_t err) {
    bool reachedEOS = false;
    {
        Mutexed<Output>::Locked output(mOutput);
        reachedEOS = output->mEncoderReachedEOS;
        if (!reachedEOS) {
            ALOGV("encoder (%s) reached EOS", mIsVideo ? "video" : "audio");
            // release all unread media buffers
            for (List<MediaBuffer*>::iterator it = output->mBufferQueue.begin();
                    it != output->mBufferQueue.end(); it++) {
                (*it)->release();
            }
            output->mBufferQueue.clear();
            output->mEncoderReachedEOS = true;
            output->mErrorCode = err;
            output->mCond.signal();

            reachedEOS = true;
            output.unlock();
            releaseEncoder();
        }
    }

    if (mStopping && reachedEOS) {
        ALOGI("encoder (%s) stopped", mIsVideo ? "video" : "audio");
        mPuller->stopSource();
        ALOGV("source (%s) stopped", mIsVideo ? "video" : "audio");
        // posting reply to everyone that's waiting
        List<sp<AReplyToken>>::iterator it;
        for (it = mStopReplyIDQueue.begin();
                it != mStopReplyIDQueue.end(); it++) {
            (new AMessage)->postReply(*it);
        }
        mStopReplyIDQueue.clear();
        mStopping = false;
        ++mGeneration;
    }
}

void MediaCodecSource::suspend() {
    CHECK(mFlags & FLAG_USE_SURFACE_INPUT);
    if (mEncoder != NULL) {
        sp<AMessage> params = new AMessage;
        params->setInt32("drop-input-frames", true);
        mEncoder->setParameters(params);
    }
}

void MediaCodecSource::resume(int64_t skipFramesBeforeUs) {
    CHECK(mFlags & FLAG_USE_SURFACE_INPUT);
    if (mEncoder != NULL) {
        sp<AMessage> params = new AMessage;
        params->setInt32("drop-input-frames", false);
        if (skipFramesBeforeUs > 0) {
            params->setInt64("skip-frames-before", skipFramesBeforeUs);
        }
        mEncoder->setParameters(params);
    }
}

status_t MediaCodecSource::feedEncoderInputBuffers() {
    MediaBuffer* mbuf = NULL;
    while (!mAvailEncoderInputIndices.empty() && mPuller->readBuffer(&mbuf)) {
        size_t bufferIndex = *mAvailEncoderInputIndices.begin();
        mAvailEncoderInputIndices.erase(mAvailEncoderInputIndices.begin());

        int64_t timeUs = 0ll;
        uint32_t flags = 0;
        size_t size = 0;

        if (mbuf != NULL) {
            CHECK(mbuf->meta_data()->findInt64(kKeyTime, &timeUs));
            timeUs += mInputBufferTimeOffsetUs;

            // push decoding time for video, or drift time for audio
            if (mIsVideo) {
                mDecodingTimeQueue.push_back(timeUs);
            } else {
#if DEBUG_DRIFT_TIME
                if (mFirstSampleTimeUs < 0ll) {
                    mFirstSampleTimeUs = timeUs;
                }

                int64_t driftTimeUs = 0;
                if (mbuf->meta_data()->findInt64(kKeyDriftTime, &driftTimeUs)
                        && driftTimeUs) {
                    driftTimeUs = timeUs - mFirstSampleTimeUs - driftTimeUs;
                }
                mDriftTimeQueue.push_back(driftTimeUs);
#endif // DEBUG_DRIFT_TIME
            }

            sp<ABuffer> inbuf;
            status_t err = mEncoder->getInputBuffer(bufferIndex, &inbuf);
            if (err != OK || inbuf == NULL) {
                mbuf->release();
                signalEOS();
                break;
            }

            size = mbuf->size();

            memcpy(inbuf->data(), mbuf->data(), size);

            if (mIsVideo) {
                // video encoder will release MediaBuffer when done
                // with underlying data.
                inbuf->setMediaBufferBase(mbuf);
            } else {
                mbuf->release();
            }
        } else {
            flags = MediaCodec::BUFFER_FLAG_EOS;
        }

        status_t err = mEncoder->queueInputBuffer(
                bufferIndex, 0, size, timeUs, flags);

        if (err != OK) {
            return err;
        }
    }

    return OK;
}

status_t MediaCodecSource::onStart(MetaData *params) {
    if (mStopping) {
        ALOGE("Failed to start while we're stopping");
        return INVALID_OPERATION;
    }

    if (mStarted) {
        ALOGI("MediaCodecSource (%s) resuming", mIsVideo ? "video" : "audio");
        if (mFlags & FLAG_USE_SURFACE_INPUT) {
            resume();
        } else {
            CHECK(mPuller != NULL);
            mPuller->resume();
        }
        return OK;
    }

    ALOGI("MediaCodecSource (%s) starting", mIsVideo ? "video" : "audio");

    status_t err = OK;

    if (mFlags & FLAG_USE_SURFACE_INPUT) {
        int64_t startTimeUs;
        if (!params || !params->findInt64(kKeyTime, &startTimeUs)) {
            startTimeUs = -1ll;
        }
        resume(startTimeUs);
    } else {
        CHECK(mPuller != NULL);
        sp<MetaData> meta = params;
        if (mSetEncoderFormat) {
            if (meta == NULL) {
                meta = new MetaData;
            }
            meta->setInt32(kKeyPixelFormat, mEncoderFormat);
            meta->setInt32(kKeyColorSpace, mEncoderDataSpace);
        }

        sp<AMessage> notify = new AMessage(kWhatPullerNotify, mReflector);
        err = mPuller->start(meta.get(), notify);
        if (err != OK) {
            return err;
        }
    }

    ALOGI("MediaCodecSource (%s) started", mIsVideo ? "video" : "audio");

    mStarted = true;
    return OK;
}

void MediaCodecSource::onMessageReceived(const sp<AMessage> &msg) {
    switch (msg->what()) {
    case kWhatPullerNotify:
    {
        int32_t eos = 0;
        if (msg->findInt32("eos", &eos) && eos) {
            ALOGV("puller (%s) reached EOS", mIsVideo ? "video" : "audio");
            signalEOS();
            break;
        }

        if (mEncoder == NULL) {
            ALOGV("got msg '%s' after encoder shutdown.", msg->debugString().c_str());
            break;
        }

        feedEncoderInputBuffers();
        break;
    }
    case kWhatEncoderActivity:
    {
        if (mEncoder == NULL) {
            break;
        }

        int32_t cbID;
        CHECK(msg->findInt32("callbackID", &cbID));
        if (cbID == MediaCodec::CB_INPUT_AVAILABLE) {
            int32_t index;
            CHECK(msg->findInt32("index", &index));

            mAvailEncoderInputIndices.push_back(index);
            feedEncoderInputBuffers();
        } else if (cbID == MediaCodec::CB_OUTPUT_AVAILABLE) {
            int32_t index;
            size_t offset;
            size_t size;
            int64_t timeUs;
            int32_t flags;

            CHECK(msg->findInt32("index", &index));
            CHECK(msg->findSize("offset", &offset));
            CHECK(msg->findSize("size", &size));
            CHECK(msg->findInt64("timeUs", &timeUs));
            CHECK(msg->findInt32("flags", &flags));

            if (flags & MediaCodec::BUFFER_FLAG_EOS) {
                mEncoder->releaseOutputBuffer(index);
                signalEOS();
                break;
            }

            sp<ABuffer> outbuf;
            status_t err = mEncoder->getOutputBuffer(index, &outbuf);
            if (err != OK || outbuf == NULL) {
                signalEOS();
                break;
            }

            MediaBuffer *mbuf = new MediaBuffer(outbuf->size());
            memcpy(mbuf->data(), outbuf->data(), outbuf->size());

            if (!(flags & MediaCodec::BUFFER_FLAG_CODECCONFIG)) {
                if (mIsVideo) {
                    int64_t decodingTimeUs;
                    if (mFlags & FLAG_USE_SURFACE_INPUT) {
                        // Time offset is not applied at
                        // feedEncoderInputBuffer() in surface input case.
                        timeUs += mInputBufferTimeOffsetUs;
                        // GraphicBufferSource is supposed to discard samples
                        // queued before start, and offset timeUs by start time
                        CHECK_GE(timeUs, 0ll);
                        // TODO:
                        // Decoding time for surface source is unavailable,
                        // use presentation time for now. May need to move
                        // this logic into MediaCodec.
                        decodingTimeUs = timeUs;
                    } else {
                        CHECK(!mDecodingTimeQueue.empty());
                        decodingTimeUs = *(mDecodingTimeQueue.begin());
                        mDecodingTimeQueue.erase(mDecodingTimeQueue.begin());
                    }
                    mbuf->meta_data()->setInt64(kKeyDecodingTime, decodingTimeUs);

                    ALOGV("[video] time %" PRId64 " us (%.2f secs), dts/pts diff %" PRId64,
                            timeUs, timeUs / 1E6, decodingTimeUs - timeUs);
                } else {
                    int64_t driftTimeUs = 0;
#if DEBUG_DRIFT_TIME
                    CHECK(!mDriftTimeQueue.empty());
                    driftTimeUs = *(mDriftTimeQueue.begin());
                    mDriftTimeQueue.erase(mDriftTimeQueue.begin());
                    mbuf->meta_data()->setInt64(kKeyDriftTime, driftTimeUs);
#endif // DEBUG_DRIFT_TIME
                    ALOGV("[audio] time %" PRId64 " us (%.2f secs), drift %" PRId64,
                            timeUs, timeUs / 1E6, driftTimeUs);
                }
                mbuf->meta_data()->setInt64(kKeyTime, timeUs);
            } else {
                mbuf->meta_data()->setInt32(kKeyIsCodecConfig, true);
            }
            if (flags & MediaCodec::BUFFER_FLAG_SYNCFRAME) {
                mbuf->meta_data()->setInt32(kKeyIsSyncFrame, true);
            }
            mbuf->setObserver(this);
            mbuf->add_ref();

            {
                Mutexed<Output>::Locked output(mOutput);
                output->mBufferQueue.push_back(mbuf);
                output->mCond.signal();
            }

            mEncoder->releaseOutputBuffer(index);
       } else if (cbID == MediaCodec::CB_ERROR) {
            status_t err;
            CHECK(msg->findInt32("err", &err));
            ALOGE("Encoder (%s) reported error : 0x%x",
                    mIsVideo ? "video" : "audio", err);
            signalEOS();
       }
       break;
    }
    case kWhatStart:
    {
        sp<AReplyToken> replyID;
        CHECK(msg->senderAwaitsResponse(&replyID));

        sp<RefBase> obj;
        CHECK(msg->findObject("meta", &obj));
        MetaData *params = static_cast<MetaData *>(obj.get());

        sp<AMessage> response = new AMessage;
        response->setInt32("err", onStart(params));
        response->postReply(replyID);
        break;
    }
    case kWhatStop:
    {
        ALOGI("encoder (%s) stopping", mIsVideo ? "video" : "audio");

        sp<AReplyToken> replyID;
        CHECK(msg->senderAwaitsResponse(&replyID));

        if (mOutput.lock()->mEncoderReachedEOS) {
            // if we already reached EOS, reply and return now
            ALOGI("encoder (%s) already stopped",
                    mIsVideo ? "video" : "audio");
            (new AMessage)->postReply(replyID);
            break;
        }

        mStopReplyIDQueue.push_back(replyID);
        if (mStopping) {
            // nothing to do if we're already stopping, reply will be posted
            // to all when we're stopped.
            break;
        }

        mStopping = true;

        // if using surface, signal source EOS and wait for EOS to come back.
        // otherwise, stop puller (which also clears the input buffer queue)
        // and wait for the EOS message. We cannot call source->stop() because
        // the encoder may still be processing input buffers.
        if (mFlags & FLAG_USE_SURFACE_INPUT) {
            mEncoder->signalEndOfInputStream();
        } else {
            mPuller->stop();
        }

        // complete stop even if encoder/puller stalled
        sp<AMessage> timeoutMsg = new AMessage(kWhatStopStalled, mReflector);
        timeoutMsg->setInt32("generation", mGeneration);
        timeoutMsg->post(kStopTimeoutUs);
        break;
    }

    case kWhatStopStalled:
    {
        int32_t generation;
        CHECK(msg->findInt32("generation", &generation));
        if (generation != mGeneration) {
             break;
        }

        if (!(mFlags & FLAG_USE_SURFACE_INPUT)) {
            ALOGV("source (%s) stopping", mIsVideo ? "video" : "audio");
            mPuller->interruptSource();
            ALOGV("source (%s) stopped", mIsVideo ? "video" : "audio");
        }
        signalEOS();
    }

    case kWhatPause:
    {
        if (mFlags & FLAG_USE_SURFACE_INPUT) {
            suspend();
        } else {
            CHECK(mPuller != NULL);
            mPuller->pause();
        }
        break;
    }
    case kWhatSetInputBufferTimeOffset:
    {
        sp<AReplyToken> replyID;
        CHECK(msg->senderAwaitsResponse(&replyID));

        CHECK(msg->findInt64("time-offset-us", &mInputBufferTimeOffsetUs));

        sp<AMessage> response = new AMessage;
        response->postReply(replyID);
        break;
    }
    default:
        TRESPASS();
    }
}

} // namespace android