qffmpegaudiodecoder.cpp

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// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qffmpegaudiodecoder_p.h"
#include "qffmpegresampler_p.h"
#include "qaudiobuffer.h"
 
#include "qffmpegplaybackengine_p.h"
#include "playbackengine/qffmpegrenderer_p.h"
#include <QtMultimedia/qplaybackoptions.h>
#include <qloggingcategory.h>
 
Q_STATIC_LOGGING_CATEGORY(qLcAudioDecoder, "qt.multimedia.ffmpeg.audioDecoder")
 
QT_BEGIN_NAMESPACE
 
namespace QFFmpeg
{
 
class SteppingAudioRenderer : public Renderer
{
    Q_OBJECT
public:
    SteppingAudioRenderer(const PlaybackEngineObjectID &id, const QAudioFormat &format)
        : Renderer(id, {}), m_format(format)
    {
    }
 
    RenderingResult renderInternal(Frame frame) override
    {
        if (!frame.isValid())
            return {};
 
        if (!m_resampler)
            m_resampler = QFFmpegResampler::createFromCodecContext(frame.codecContext(), m_format);
 
        if (m_resampler)
            emit newAudioBuffer(m_resampler->resample(frame.avFrame()));
 
        return {};
    }
 
signals:
    void newAudioBuffer(QAudioBuffer);
 
private:
    QAudioFormat m_format;
    std::unique_ptr<QFFmpegResampler> m_resampler;
};
 
class AudioDecoder : public PlaybackEngine
{
    Q_OBJECT
public:
    explicit AudioDecoder(const QAudioFormat &format, const QPlaybackOptions &options)
        : PlaybackEngine{ options }, m_format(format)
    {
    }
 
    RendererPtr createRenderer(QPlatformMediaPlayer::TrackType trackType) override
    {
        if (trackType != QPlatformMediaPlayer::AudioStream)
            return RendererPtr{ {}, {} };
 
        auto result = createPlaybackEngineObject<SteppingAudioRenderer>(m_format);
        m_audioRenderer = result.get();
 
        connect(result.get(), &SteppingAudioRenderer::newAudioBuffer, this,
                &AudioDecoder::newAudioBuffer);
 
        return result;
    }
 
    void nextBuffer()
    {
        Q_ASSERT(m_audioRenderer);
        Q_ASSERT(!m_audioRenderer->isStepForced());
 
        m_audioRenderer->doForceStep();
        // updateObjectsPausedState();
    }
 
signals:
    void newAudioBuffer(QAudioBuffer);
 
private:
    QPointer<Renderer> m_audioRenderer;
    QAudioFormat m_format;
};
} // namespace QFFmpeg
 
QFFmpegAudioDecoder::QFFmpegAudioDecoder(QAudioDecoder *parent)
    : QPlatformAudioDecoder(parent)
{
}
 
QFFmpegAudioDecoder::~QFFmpegAudioDecoder() = default;
 
QUrl QFFmpegAudioDecoder::source() const
{
    return m_url;
}
 
void QFFmpegAudioDecoder::setSource(const QUrl &fileName)
{
    stop();
    m_sourceDevice = nullptr;
 
    if (std::exchange(m_url, fileName) != fileName)
        sourceChanged();
}
 
QIODevice *QFFmpegAudioDecoder::sourceDevice() const
{
    return m_sourceDevice;
}
 
void QFFmpegAudioDecoder::setSourceDevice(QIODevice *device)
{
    stop();
    m_url.clear();
    if (std::exchange(m_sourceDevice, device) != device)
        sourceChanged();
}
 
void QFFmpegAudioDecoder::start()
{
    qCDebug(qLcAudioDecoder) << "start";
    auto checkNoError = [this]() {
        if (error() == QAudioDecoder::NoError)
            return true;
 
        durationChanged(kInvalidDuration);
        positionChanged(kInvalidPosition);
 
        m_decoder.reset();
 
        return false;
    };
 
    QPlaybackOptions defaultOptions;
    m_decoder = std::make_unique<AudioDecoder>(m_audioFormat, defaultOptions);
    connect(m_decoder.get(), &AudioDecoder::errorOccured, this, &QFFmpegAudioDecoder::errorSignal);
    connect(m_decoder.get(), &AudioDecoder::endOfStream, this, &QFFmpegAudioDecoder::done);
    connect(m_decoder.get(), &AudioDecoder::newAudioBuffer, this,
            &QFFmpegAudioDecoder::newAudioBuffer);
 
    QFFmpeg::MediaDataHolder::Maybe media =
            QFFmpeg::MediaDataHolder::create(m_url, m_sourceDevice, defaultOptions, nullptr);
 
    if (media) {
        Q_ASSERT(media.value());
        if (media.value()->streamInfo(QPlatformMediaPlayer::AudioStream).isEmpty())
            error(QAudioDecoder::FormatError,
                  QLatin1String("The media doesn't contain an audio stream"));
        else
            m_decoder->setMedia(std::move(*media.value()));
    } else {
        auto [code, description] = media.error();
        errorSignal(code, description);
    }
 
    if (!checkNoError())
        return;
 
    m_decoder->setState(QMediaPlayer::PausedState);
    if (!checkNoError())
        return;
 
    m_decoder->nextBuffer();
    if (!checkNoError())
        return;
 
    durationChanged(std::chrono::milliseconds{ QFFmpeg::toUserDuration(m_decoder->duration()).get() });
    setIsDecoding(true);
}
 
void QFFmpegAudioDecoder::stop()
{
    qCDebug(qLcAudioDecoder) << ">>>>> stop";
    if (m_decoder) {
        m_decoder.reset();
        done();
    }
}
 
QAudioFormat QFFmpegAudioDecoder::audioFormat() const
{
    return m_audioFormat;
}
 
void QFFmpegAudioDecoder::setAudioFormat(const QAudioFormat &format)
{
    if (std::exchange(m_audioFormat, format) != format)
        formatChanged(m_audioFormat);
}
 
QAudioBuffer QFFmpegAudioDecoder::read()
{
    auto buffer = std::exchange(m_audioBuffer, QAudioBuffer{});
    if (!buffer.isValid())
        return buffer;
    qCDebug(qLcAudioDecoder) << "reading buffer" << buffer.startTime();
    bufferAvailableChanged(false);
    if (m_decoder)
        m_decoder->nextBuffer();
    return buffer;
}
 
void QFFmpegAudioDecoder::newAudioBuffer(const QAudioBuffer &b)
{
    Q_ASSERT(b.isValid());
    Q_ASSERT(!m_audioBuffer.isValid());
    Q_ASSERT(!bufferAvailable());
 
    qCDebug(qLcAudioDecoder) << "new audio buffer" << b.startTime();
    m_audioBuffer = b;
    // QAudioBuffer::startTime is in microseconds; convert to milliseconds
    const qint64 pos = b.startTime();
    positionChanged(
            std::chrono::round<std::chrono::milliseconds>(std::chrono::microseconds{ pos }));
    bufferAvailableChanged(b.isValid());
    bufferReady();
}
 
void QFFmpegAudioDecoder::done()
{
    qCDebug(qLcAudioDecoder) << ">>>>> DONE!";
    finished();
}
 
void QFFmpegAudioDecoder::errorSignal(int err, const QString &errorString)
{
    // unfortunately the error enums for QAudioDecoder and QMediaPlayer aren't identical.
    // Map them.
    switch (QMediaPlayer::Error(err)) {
    case QMediaPlayer::NoError:
        error(QAudioDecoder::NoError, errorString);
        break;
    case QMediaPlayer::ResourceError:
        error(QAudioDecoder::ResourceError, errorString);
        break;
    case QMediaPlayer::FormatError:
        error(QAudioDecoder::FormatError, errorString);
        break;
    case QMediaPlayer::NetworkError:
        // fall through, Network error doesn't exist in QAudioDecoder
    case QMediaPlayer::AccessDeniedError:
        error(QAudioDecoder::AccessDeniedError, errorString);
        break;
    }
}
 
QT_END_NAMESPACE
 
#include "moc_qffmpegaudiodecoder_p.cpp"
 
#include "qffmpegaudiodecoder.moc"