p26001-store-acs-soc-fw-app/video/core/AudioDecoder.cpp

/*
 *******************************************************************************
 *                                   INCLUDE
 *******************************************************************************
 */
#include "AudioDecoder.h"
#include "Logger.h"
#include "Demuxer.h"
#include "System.h"
#include <Poco/Exception.h>
#include <Logger.h>

namespace Video
{
namespace Core
{
/*
 *******************************************************************************
 * 追帧（catch-up）阈值配置
 * 说明：所有阈值均以"队列中待解码包个数"为单位。
 *       音频帧典型时长约 20ms（AAC），队列上限 300，约 6s 缓冲。
 *******************************************************************************
 */
namespace
{
constexpr int CATCH_UP_ENTER = 10;
constexpr int CATCH_UP_EXIT  = 2;

constexpr int DROP_LEVEL_1 = 6;
constexpr int DROP_LEVEL_2 = 15;
constexpr int DROP_LEVEL_3 = 30;
}
/*
 *******************************************************************************
 * *                                CLASS DEFINE
 *******************************************************************************
 */
AudioDecodeHandler::AudioDecodeHandler(const std::string& name, CodecID codecID, AudioComponent::Ptr pPrevious)
    : _pPrevious(pPrevious)
{
}

AudioDecodeHandler::~AudioDecodeHandler()
{
}

void AudioDecodeHandler::conceal(Packet::Ptr pPacket)
{
    (void)pPacket;
}

/*
 *******************************************************************************
 *                                CLASS DEFINE
 *******************************************************************************
 */
AudioDecoder::AudioDecoder(const std::string& name)
    : AbstractAudioInput(name), _synchronizer(name + "/sync"),

      _catchUpEnabled(name.find("NET") != std::string::npos ? true : false), _isCatchingUp(false), _dropPhase(0)
{
}

AudioDecoder::~AudioDecoder()
{
}

void AudioDecoder::start()
{
    run();
}

void AudioDecoder::stop()
{
    cancel();
    setTimeline(0);

    _isCatchingUp = false;
    _dropPhase    = 0;
}

Frame::Ptr AudioDecoder::readFrame()
{
    if (previousComponents().size() == 0 || packetQueues().empty())
        throw Poco::NotFoundException("No previous components");

    updateCatchUpState();

    Frame::Ptr pFrame = nullptr;

    if (!_pHandler.isNull())
    {
        pFrame = _pHandler->read();
        if (!pFrame.isNull())
        {
            syncFrame(pFrame, _isCatchingUp);
            return pFrame;
        }
    }

    while (pFrame.isNull())
    {
        Packet::Ptr pPacket;

        try
        {
            long timeOut = _isCatchingUp ? 1 : 1000;
            pPacket      = packetQueues().first()->dequeue(timeOut);
        }
        catch (std::exception& e)
        {
            if (packetQueues().first()->size() == 0)
            {
                if (_isCatchingUp)
                {
                    _isCatchingUp = false;
                    _dropPhase    = 0;
                    _synchronizer.reset();
                    logger().information("%s: catch-up exit (queue drained)", name());
                }
            }
            setTimeline(0);
            throw;
        }

        if (serialCodeWatcher().isChanged(pPacket->serialCode(), true))
        {
            auto pPrevious = previousComponents().first();
            auto pDemuxer  = pPrevious.cast<Demuxer>();
            if (pDemuxer)
            {
                auto pEncoder = pDemuxer->audioEncoder();
                pEncoder->config().copyTo(config());
                serialCodeManager().increment();

                _pHandler = AudioDecodeHandler::create(pEncoder->getCodecID(), pEncoder);

                if (_catchUpEnabled)
                {
                    while (packetQueues().first()->size() > 2)
                    {
                        try
                        {
                            packetQueues().first()->dequeue(0);
                        }
                        catch (...)
                        {
                            break;
                        }
                    }
                }
            }
            else
                throw Poco::NotImplementedException(
                    Poco::format("Unsupported previous component: %s", pPrevious->name()));
        }

        if (_isCatchingUp && shouldDropPacket())
        {
            _pHandler->conceal(pPacket);
            continue;
        }

        _pHandler->write(pPacket);
        pFrame = _pHandler->read();
    }

    syncFrame(pFrame, _isCatchingUp);
    return pFrame;
}

void AudioDecoder::onLink(Core::Component::Ptr pPrevious)
{
    if (!packetQueues().empty() && packetQueues().firstComponent() != pPrevious)
        throw Poco::LogicException(name() + ": Support only one previous component, conflict with: " +
                                   pPrevious->name() + ", Current: " + packetQueues().firstComponent()->name());

    packetQueues().add(pPrevious, name(), MediaType::AUDIO);
}

void AudioDecoder::onUnlink(Core::Component::Ptr pPrevious)
{
    packetQueues().remove(pPrevious);
}

void AudioDecoder::syncFrame(Frame::Ptr pFrame, bool isCatchingUp)
{
    if (!isCatchingUp)
        _synchronizer.syncFrame(pFrame->timestamp);
    setTimeline(pFrame->timestamp);
    pFrame->timestamp = System::timestamp();
}

void AudioDecoder::updateCatchUpState()
{
    if (!_catchUpEnabled)
        return;

    const int queueSize = packetQueues().first()->size();

    if (!_isCatchingUp && queueSize > CATCH_UP_ENTER)
    {
        _isCatchingUp = true;
        _dropPhase    = 0;
        logger().information("%s: catch-up enter (queue=%d)", name(), queueSize);
    }
    else if (_isCatchingUp && queueSize <= CATCH_UP_EXIT)
    {
        _isCatchingUp = false;
        _dropPhase    = 0;

        _synchronizer.reset();
        logger().information("%s: catch-up exit (queue=%d)", name(), queueSize);
    }
}

bool AudioDecoder::shouldDropPacket()
{
    const int queueSize = packetQueues().first()->size();
    bool      drop      = false;

    if (queueSize >= DROP_LEVEL_3)
    {
        drop = (_dropPhase % 3) != 2;
    }
    else if (queueSize >= DROP_LEVEL_2)
    {
        drop = (_dropPhase % 2) == 0;
    }
    else
    {
        drop = (_dropPhase % 3) == 0;
    }

    _dropPhase++;
    return drop;
}
}
}