diff --git a/ffmpeg/CMakeLists.txt b/ffmpeg/CMakeLists.txt
index 49ea8dc..1d4af4e 100644
--- a/ffmpeg/CMakeLists.txt
+++ b/ffmpeg/CMakeLists.txt
@@ -37,6 +37,8 @@ set(PROJECT_SOURCES
     averror.h
     averrormanager.cc
     averrormanager.hpp
+    clock.cc
+    clock.hpp
     codeccontext.cpp
     codeccontext.h
     colorspace.hpp
diff --git a/ffmpeg/clock.cc b/ffmpeg/clock.cc
new file mode 100644
index 0000000..df2dae1
--- /dev/null
+++ b/ffmpeg/clock.cc
@@ -0,0 +1,139 @@
+#include "clock.hpp"
+
+#include <QMutex>
+
+extern "C" {
+#include <libavutil/time.h>
+}
+
+namespace Ffmpeg {
+
+class Clock::ClockPrivate
+{
+public:
+    explicit ClockPrivate(Clock *q)
+        : q_ptr(q)
+    {}
+
+    Clock *q_ptr;
+
+    mutable QMutex mutex;
+    qint64 pts = 0;       // 当前 AVFrame 的时间戳 microseconds
+    qint64 pts_drift = 0; // 时钟漂移量，用于计算当前时钟的状态 microseconds
+    qint64 last_updated = av_gettime_relative(); // 上一次更新时钟状态的时间 microseconds
+    bool paused = false;                         // 是否暂停播放
+
+    static constexpr QPair<double, double> speedRange = {0.5, 3.0};
+    static constexpr auto speedStep = 0.5;
+    static std::atomic<double> speed;
+
+    static constexpr auto diffThreshold = 50 * 1000; // 50ms
+
+    static Clock *g_clock;
+};
+
+std::atomic<double> Clock::ClockPrivate::speed = 1.0;
+Clock *Clock::ClockPrivate::g_clock = nullptr;
+
+Clock::Clock(QObject *parent)
+    : QObject{parent}
+    , d_ptr(new ClockPrivate(this))
+{}
+
+Clock::~Clock() = default;
+
+auto Clock::pts() -> qint64
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->pts;
+}
+
+auto Clock::ptsDrift() -> qint64
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->pts_drift;
+}
+
+auto Clock::lastUpdated() -> qint64
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->last_updated;
+}
+
+auto Clock::paused() -> bool
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->paused;
+}
+
+void Clock::setPaused(bool value)
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    d_ptr->paused = value;
+    if (!d_ptr->paused) {
+        d_ptr->last_updated = av_gettime_relative();
+    }
+}
+
+void Clock::update(qint64 pts, qint64 time)
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    if (d_ptr->last_updated && !d_ptr->paused) {
+        qint64 time_diff = (time - d_ptr->last_updated) * speed();
+        d_ptr->pts_drift = (pts - d_ptr->pts) - time_diff;
+    }
+    d_ptr->pts = pts;
+    d_ptr->last_updated = time;
+}
+
+auto Clock::getDelayWithMaster() -> qint64
+{
+    Q_ASSERT(Clock::ClockPrivate::g_clock);
+    auto pts_drift = ptsDrift();
+    if (this == Clock::ClockPrivate::g_clock) {
+        return pts_drift;
+    }
+    pts_drift -= Clock::ClockPrivate::g_clock->ptsDrift();
+    return pts_drift;
+}
+
+auto Clock::adjustDelay(qint64 &delay) -> bool
+{
+    if (speed() > 1.0 && delay < 0) {
+        return false;
+    } else if (delay < -Clock::ClockPrivate::diffThreshold) {
+        return false;
+    } else if (qAbs(delay) <= Clock::ClockPrivate::diffThreshold) {
+        delay = 0;
+        return true;
+    }
+    delay -= Clock::ClockPrivate::diffThreshold;
+    return true;
+}
+
+auto Clock::speedRange() -> QPair<double, double>
+{
+    return Clock::ClockPrivate::speedRange;
+}
+
+auto Clock::speedStep() -> double
+{
+    return Clock::ClockPrivate::speedStep;
+}
+
+void Clock::setSpeed(double value)
+{
+    Clock::ClockPrivate::speed.store(value);
+}
+
+auto Clock::speed() -> double
+{
+    return Clock::ClockPrivate::speed.load();
+}
+
+void Clock::setMaster(Clock *clock)
+{
+    Clock::ClockPrivate::g_clock = clock;
+}
+
+} // namespace Ffmpeg
diff --git a/ffmpeg/clock.hpp b/ffmpeg/clock.hpp
new file mode 100644
index 0000000..f65209d
--- /dev/null
+++ b/ffmpeg/clock.hpp
@@ -0,0 +1,43 @@
+#ifndef CLOCK_HPP
+#define CLOCK_HPP
+
+#include <QObject>
+
+namespace Ffmpeg {
+
+class Clock : public QObject
+{
+public:
+    explicit Clock(QObject *parent = nullptr);
+    ~Clock() override;
+
+    auto pts() -> qint64;
+    auto ptsDrift() -> qint64;
+    auto lastUpdated() -> qint64;
+
+    void setPaused(bool value);
+    auto paused() -> bool;
+
+    void update(qint64 pts, qint64 time);
+
+    auto getDelayWithMaster() -> qint64;
+
+    // return true if delay is valid
+    static auto adjustDelay(qint64 &delay) -> bool;
+
+    auto speedRange() -> QPair<double, double>;
+    auto speedStep() -> double;
+    static void setSpeed(double value);
+    static auto speed() -> double;
+
+    // not thread safe and not delete clock
+    static void setMaster(Clock *clock);
+
+private:
+    class ClockPrivate;
+    QScopedPointer<ClockPrivate> d_ptr;
+};
+
+} // namespace Ffmpeg
+
+#endif // CLOCK_HPP
diff --git a/ffmpeg/ffmpeg.pro b/ffmpeg/ffmpeg.pro
index acc70bd..aecd18f 100644
--- a/ffmpeg/ffmpeg.pro
+++ b/ffmpeg/ffmpeg.pro
@@ -19,6 +19,7 @@ SOURCES += \
     avcontextinfo.cpp \
     averror.cpp \
     averrormanager.cc \
+    clock.cc \
     codeccontext.cpp \
     decoder.cc \
     decoderaudioframe.cpp \
@@ -44,6 +45,7 @@ HEADERS += \
     avcontextinfo.h \
     averror.h \
     averrormanager.hpp \
+    clock.hpp \
     codeccontext.h \
     colorspace.hpp \
     decoder.h \