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..587caa8
--- /dev/null
+++ b/ffmpeg/clock.cc
@@ -0,0 +1,143 @@
+#include "clock.hpp"
+
+#include <QMutex>
+
+extern "C" {
+#include <libavutil/time.h>
+}
+
+namespace Ffmpeg {
+
+static Clock *g_clock = nullptr;
+
+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
+    qint64 pts_drift = 0;    // 时钟漂移量，用于计算当前时钟的状态
+    qint64 last_updated = 0; // 上一次更新时钟状态的时间
+    double speed = 1.0;      // 播放速度，用于调整音视频的播放速度
+    bool paused = false;     // 是否暂停播放
+
+    static constexpr auto drop_threshold = 50 * 1000; // 50ms 丢帧阈值
+    static constexpr auto sync_threshold = 10 * 1000; // 10ms 同步阈值
+};
+
+Clock::Clock(QObject *parent)
+    : QObject{parent}
+    , d_ptr(new ClockPrivate(this))
+{}
+
+Clock::~Clock() = default;
+
+auto Clock::getPts() -> qint64
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->pts;
+}
+
+auto Clock::getPtsDrift() -> qint64
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->pts_drift;
+}
+
+auto Clock::getLastUpdated() -> qint64
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->last_updated;
+}
+
+auto Clock::getSpeed() -> double
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->speed;
+}
+
+void Clock::setSpeed(double value)
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    d_ptr->speed = value;
+}
+
+auto Clock::isPaused() -> bool
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    return d_ptr->paused;
+}
+
+void Clock::setPaused(bool value)
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    if (d_ptr->paused != value) {
+        d_ptr->paused = value;
+        if (d_ptr->paused) {
+            d_ptr->last_updated = av_gettime_relative();
+        }
+    }
+}
+
+void Clock::reset(qint64 pos)
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    d_ptr->pts = pos;
+    d_ptr->pts_drift = av_gettime_relative();
+    d_ptr->last_updated = d_ptr->pts_drift;
+    d_ptr->paused = false;
+}
+
+void Clock::update(qint64 pts, qint64 time)
+{
+    QMutexLocker locker(&d_ptr->mutex);
+    if (d_ptr->last_updated && !d_ptr->paused) {
+        // 计算时钟漂移量
+        d_ptr->pts_drift += (pts - d_ptr->pts) * d_ptr->speed + (time - d_ptr->last_updated);
+    }
+    // 更新当前 AVFrame 的时间戳和上一次更新时钟状态的时间
+    d_ptr->pts = pts;
+    d_ptr->last_updated = time;
+}
+
+auto Clock::getClock(qint64 pts) -> qint64
+{
+    Q_ASSERT(g_clock);
+
+    QMutexLocker locker(&d_ptr->mutex);
+    qint64 time = av_gettime_relative();
+    qint64 clock = d_ptr->pts_drift + pts * d_ptr->speed;
+    if (d_ptr->paused) {
+        clock = d_ptr->last_updated;
+    } else {
+        clock += time - d_ptr->last_updated;
+    }
+    // 计算全局时钟的状态与当前时钟的状态之间的差值
+    return clock + g_clock->getPtsDrift() - getPtsDrift();
+}
+
+auto Clock::getDiff(qint64 &diff) -> bool
+{
+    qint64 clock = getClock(d_ptr->pts);
+    diff = clock - av_gettime_relative();
+    if (diff <= -d_ptr->drop_threshold) { // 丢帧
+        d_ptr->pts_drift = clock - d_ptr->pts;
+        return false;
+    } else if (diff <= d_ptr->sync_threshold) {
+        diff = 0;
+    }
+
+    return true;
+}
+
+void Clock::setMaster(Clock *clock)
+{
+    g_clock = clock;
+}
+
+} // namespace Ffmpeg
diff --git a/ffmpeg/clock.hpp b/ffmpeg/clock.hpp
new file mode 100644
index 0000000..0fe6fcf
--- /dev/null
+++ b/ffmpeg/clock.hpp
@@ -0,0 +1,57 @@
+#ifndef CLOCK_HPP
+#define CLOCK_HPP
+
+#include <QObject>
+
+namespace Ffmpeg {
+
+class Clock : public QObject
+{
+public:
+    explicit Clock(QObject *parent = nullptr);
+    ~Clock() override;
+
+    // 获取当前 AVFrame 的时间戳
+    auto getPts() -> qint64;
+
+    // 获取时钟漂移量
+    auto getPtsDrift() -> qint64;
+
+    // 获取上一次更新时钟状态的时间
+    auto getLastUpdated() -> qint64;
+
+    // 获取播放速度
+    auto getSpeed() -> double;
+
+    // 设置播放速度
+    void setSpeed(double value);
+
+    // 获取是否暂停播放
+    auto isPaused() -> bool;
+
+    // 设置是否暂停播放
+    void setPaused(bool value);
+
+    // 重置时钟状态
+    void reset(qint64 pos);
+
+    // 更新时钟状态
+    void update(qint64 pts, qint64 time);
+
+    // 获取当前时钟的状态
+    auto getClock(qint64 pts) -> qint64;
+
+    // 获取当前时钟的状态与上一次更新时钟状态的时间差
+    auto getDiff(qint64 &diff) -> bool;
+
+    // not thread safe
+    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 \