Feat: Implement H264 for Linux client with dynamic libx264 loading

common/PTYHandler.h

@@ -202,6 +202,8 @@ private:
             // macOS locale settings
             setenv("LANG", "en_US.UTF-8", 1);
             setenv("LC_ALL", "en_US.UTF-8", 1);
+            // Disable zsh session save/restore (causes errors in PTY)
+            setenv("SHELL_SESSIONS_DISABLE", "1", 1);
 
             // Try zsh first (macOS default), fallback to bash
             if (access("/bin/zsh", X_OK) == 0) {

common/commands.h

@@ -1048,6 +1048,14 @@ enum QualityLevel {
     QUALITY_COUNT   = 6,
 };
 
+// 屏幕压缩算法常量 (所有平台共用)
+#ifndef ALGORITHM_GRAY
+#define ALGORITHM_GRAY    0   // 灰度压缩
+#define ALGORITHM_DIFF    1   // 差分压缩 (BGRA)
+#define ALGORITHM_H264    2   // H264 硬件编码
+#define ALGORITHM_RGB565  3   // RGB565 压缩
+#endif
+
 /* 质量配置(与 QualityLevel 对应)
 - strategy = 0：1080p 限制
 - strategy = 1：原始分辨率

linux/ScreenHandler.h

@@ -4,6 +4,7 @@
 #include "LinuxConfig.h"
 #include "ClipboardHandler.h"
 #include "common/FileTransferV2.h"
+#include "X264Encoder.h"
 #include <dlfcn.h>
 #include <sys/stat.h>
 #include <thread>
@@ -12,6 +13,7 @@
 #include <vector>
 #include <cstring>
 #include <stdexcept>
+#include <memory>
 
 // 客户端 ID（定义在 main.cpp）
 extern uint64_t g_myClientID;
@@ -110,27 +112,39 @@ struct XGCValues_LNX {
 #define IncludeInferiors 1
 
 // ============== 屏幕算法常量 ==============
-#define ALGORITHM_GRAY    0
+// 常量定义已移至 commands.h: ALGORITHM_GRAY, ALGORITHM_DIFF, ALGORITHM_H264, ALGORITHM_RGB565
-#define ALGORITHM_DIFF    1
-#define ALGORITHM_H264    2
-#define ALGORITHM_RGB565  3
 
-// 算法支持表（编译时常量，日后支持 H264 时改为 true）
+// 检查算法是否支持（H264 需要运行时检测）
-static const bool g_SupportedAlgo[] = {
+inline bool IsAlgorithmSupported(uint8_t algo) {
-    true,   // ALGORITHM_GRAY   = 0
+    switch (algo) {
-    true,   // ALGORITHM_DIFF   = 1
+    case ALGORITHM_GRAY:
-    false,  // ALGORITHM_H264   = 2
+    case ALGORITHM_DIFF:
-    true,   // ALGORITHM_RGB565 = 3
+    case ALGORITHM_RGB565:
-};
+        return true;
+    case ALGORITHM_H264:
+        return X264Encoder::IsAvailable();
+    default:
+        return false;
+    }
+}
 
 // 不支持的算法降级为 RGB565
 inline uint8_t GetEffectiveAlgorithm(uint8_t algo) {
-    if (algo > 3 || !g_SupportedAlgo[algo]) {
+    if (!IsAlgorithmSupported(algo)) {
+        Mprintf(">>> Algorithm %d not supported, fallback to RGB565\n", algo);
         return ALGORITHM_RGB565;
     }
     return algo;
 }
 
+// 码率到 CRF 映射 (参考 Windows/macOS 实现)
+inline int BitRateToCRF(int bitrate) {
+    if (bitrate >= 3000) return 20;  // 高质量
+    if (bitrate >= 2000) return 23;  // 中等
+    if (bitrate >= 1200) return 26;  // 较低
+    return 30;                        // 最低
+}
+
 // ============== 颜色转换函数 ==============
 
 // BGRA → 灰度 (Y = 0.299R + 0.587G + 0.114B)
@@ -538,7 +552,8 @@ public:
           m_inputDisplay(nullptr),
           m_width(0), m_height(0),
           m_pixmap(0), m_gc(nullptr), m_xtestWarned(false),
-          m_bAlgorithm(ALGORITHM_DIFF), m_maxFPS(10), m_qualityLevel(QUALITY_ADAPTIVE)
+          m_bAlgorithm(ALGORITHM_DIFF), m_maxFPS(10), m_qualityLevel(QUALITY_ADAPTIVE),
+          m_h264Bitrate(2000)
     {
         if (!client) {
             throw std::invalid_argument("IOCPClient pointer cannot be null");
@@ -883,12 +898,28 @@ public:
             // 应用帧率
             m_maxFPS.store(profile.maxFPS);
 
+            // 应用码率（H264 使用）
+            int oldBitrate = m_h264Bitrate;
+            m_h264Bitrate = profile.bitRate;
+
             // 应用算法（带降级处理）
             uint8_t algo = GetEffectiveAlgorithm(profile.algorithm);
+            uint8_t oldAlgo = m_bAlgorithm.load();
             m_bAlgorithm.store(algo);
 
-            Mprintf(">>> Quality: Level=%d, FPS=%d, Algo=%d->%d\n",
+            // 如果 H264 参数变化，需要重新初始化编码器
-                    level, profile.maxFPS, profile.algorithm, algo);
+            if (algo == ALGORITHM_H264 && oldAlgo == ALGORITHM_H264 &&
+                (oldBitrate != m_h264Bitrate)) {
+                // 码率变化，重置编码器（下次编码时重新初始化）
+                if (m_h264Encoder) {
+                    m_h264Encoder->close();
+                    m_h264Encoder.reset();
+                    Mprintf(">>> H264 encoder reset due to bitrate change\n");
+                }
+            }
+
+            Mprintf(">>> Quality: Level=%d, FPS=%d, Algo=%d->%d, Bitrate=%d\n",
+                    level, profile.maxFPS, profile.algorithm, algo, profile.bitRate);
         } else {
             // 自适应模式 (level=-1)：由服务端动态调整，不做处理
             Mprintf(">>> Quality: Adaptive mode\n");
@@ -1054,11 +1085,15 @@ private:
     std::vector<uint8_t> m_diffBuffer;
 
     // 自适应质量控制
-    std::atomic<uint8_t> m_bAlgorithm;  // 当前算法 (ALGORITHM_DIFF/RGB565/GRAY)
+    std::atomic<uint8_t> m_bAlgorithm;  // 当前算法 (ALGORITHM_DIFF/RGB565/GRAY/H264)
     std::atomic<int> m_maxFPS;          // 最大帧率
     int8_t m_qualityLevel;              // 当前质量等级 (-1=自适应, 0-5=具体等级)
     LinuxConfig m_config;                // 配置持久化 (~/.config/ghost/config.conf)
 
+    // H264 编码器
+    std::unique_ptr<X264Encoder> m_h264Encoder;
+    int m_h264Bitrate;                   // 码率 (kbps)
+
     // X11 截屏，输出 BGRA 格式（自底向上，与 BMP 一致）
     // 使用 XCopyArea 将 root window 拷贝到离屏 Pixmap，再对 Pixmap 调用 XGetImage
     // 这样可以避免合成窗口管理器（Mutter 等）导致的 BadMatch 错误
@@ -1151,6 +1186,59 @@ private:
         std::swap(m_prevFrame, m_currFrame);
     }
 
+    // 发送 H264 编码帧
+    void SendH264Frame(bool forceKeyframe = false)
+    {
+        if (!CaptureScreen(m_currFrame)) return;
+        if (!m_client) return;
+
+        // 惰性初始化编码器
+        if (!m_h264Encoder) {
+            m_h264Encoder.reset(new X264Encoder());
+            int fps = m_maxFPS.load();
+            if (fps <= 0) fps = 20;
+            int crf = BitRateToCRF(m_h264Bitrate);
+            if (!m_h264Encoder->open(m_bmpHeader.biWidth, m_bmpHeader.biHeight, fps, crf)) {
+                Mprintf("*** H264 encoder init failed, falling back to RGB565\n");
+                m_bAlgorithm.store(ALGORITHM_RGB565);
+                m_h264Encoder.reset();
+                SendDiffFrame();
+                return;
+            }
+            Mprintf(">>> H264 encoder initialized: %dx%d @ %d fps, CRF=%d\n",
+                    m_bmpHeader.biWidth, m_bmpHeader.biHeight, fps, crf);
+        }
+
+        // 编码当前帧
+        uint8_t* encodedData = nullptr;
+        uint32_t encodedSize = 0;
+
+        // direction=1 表示 bottom-up (BMP 格式)
+        int result = m_h264Encoder->encode(
+            m_currFrame.data(), 32, m_bmpHeader.biWidth * 4,
+            m_bmpHeader.biWidth, m_bmpHeader.biHeight,
+            &encodedData, &encodedSize, 1);
+
+        if (result != 0 || !encodedData || encodedSize == 0) {
+            return;
+        }
+
+        // 构建数据包: [TOKEN_NEXTSCREEN][algo][cursorX][cursorY][cursorType][H264Data]
+        uint32_t headerSize = 1 + 1 + 2 * sizeof(int32_t) + 1;
+        std::vector<uint8_t> packet(headerSize + encodedSize);
+
+        packet[0] = TOKEN_NEXTSCREEN;
+        packet[1] = ALGORITHM_H264;
+
+        int32_t cursorX = 0, cursorY = 0;
+        memcpy(&packet[2], &cursorX, sizeof(int32_t));
+        memcpy(&packet[6], &cursorY, sizeof(int32_t));
+        packet[10] = 0;  // cursorType
+
+        memcpy(&packet[headerSize], encodedData, encodedSize);
+        m_client->Send2Server((char*)packet.data(), packet.size());
+    }
+
     // 差异比较算法（支持 DIFF/RGB565/GRAY）
     // 输出格式: [byteOffset(4) + length(4) + pixel data] ...
     // DIFF: length = 字节数, data = BGRA 原始数据
@@ -1243,10 +1331,34 @@ private:
             // 发送第一帧
             SendFirstScreen();
 
+            uint8_t currentAlgo = m_bAlgorithm.load();
+
             while (m_running) {
                 uint64_t start = GetTickMs();
+                uint8_t algo = m_bAlgorithm.load();
 
-                SendDiffFrame();
+                // 算法切换处理
+                if (algo != currentAlgo) {
+                    currentAlgo = algo;
+                    if (algo == ALGORITHM_H264) {
+                        // 切换到 H264，发送关键帧
+                        SendH264Frame(true);
+                    } else {
+                        // 切换离开 H264，关闭编码器并发送完整帧
+                        if (m_h264Encoder) {
+                            m_h264Encoder->close();
+                            m_h264Encoder.reset();
+                        }
+                        SendFirstScreen();
+                    }
+                } else {
+                    // 正常帧
+                    if (algo == ALGORITHM_H264) {
+                        SendH264Frame(false);
+                    } else {
+                        SendDiffFrame();
+                    }
+                }
 
                 // 动态计算帧间隔（根据当前 maxFPS）
                 int fps = m_maxFPS.load();
@@ -1260,6 +1372,12 @@ private:
                 }
             }
 
+            // 清理 H264 编码器
+            if (m_h264Encoder) {
+                m_h264Encoder->close();
+                m_h264Encoder.reset();
+            }
+
             Mprintf(">>> ScreenHandler CaptureLoop stopped\n");
         } catch (const std::exception& e) {
             Mprintf("*** CaptureLoop exception: %s ***\n", e.what());

linux/X264Encoder.h

@@ -0,0 +1,471 @@
+#pragma once
+/**
+ * X264Encoder.h - Linux H264 Encoder using libx264
+ *
+ * Features:
+ *   - Dynamic library loading (dlopen/dlsym)
+ *   - Automatic fallback if libx264 not available
+ *   - Manual BGRA→I420 conversion (no libyuv dependency)
+ *   - API compatible with Windows X264Encoder
+ *
+ * Requirements:
+ *   - libx264 installed (apt install libx264-dev)
+ *   - If not installed, H264 encoding is disabled
+ */
+
+#include <stdint.h>
+#include <cstring>
+#include <cstdlib>
+#include <dlfcn.h>
+#include <vector>
+
+// Include x264 header for struct definitions
+// The library is dynamically loaded at runtime
+extern "C" {
+#include "../compress/x264/x264.h"
+}
+
+// ============== X264Encoder Class ==============
+
+class X264Encoder {
+public:
+    // Check if libx264 is available on this system
+    static bool IsAvailable() {
+        static int available = -1;
+        if (available < 0) {
+            void* handle = TryLoadLibrary();
+            available = (handle != nullptr) ? 1 : 0;
+            if (handle) {
+                dlclose(handle);
+                fprintf(stderr, ">>> X264Encoder: libx264 available\n");
+            } else {
+                fprintf(stderr, "*** X264Encoder: libx264 not found (%s)\n", dlerror());
+            }
+        }
+        return available == 1;
+    }
+
+    X264Encoder()
+        : m_x264Handle(nullptr)
+        , m_encoder(nullptr)
+        , m_picIn(nullptr)
+        , m_picOut(nullptr)
+        , m_width(0)
+        , m_height(0)
+    {
+        memset(&m_param, 0, sizeof(m_param));
+        clearFunctionPointers();
+    }
+
+    ~X264Encoder() {
+        close();
+    }
+
+    bool open(int width, int height, int fps, int crf) {
+        close();
+
+        // Load library
+        if (!loadLibrary()) {
+            fprintf(stderr, "*** X264Encoder::open: loadLibrary failed\n");
+            return false;
+        }
+
+        // Round to even dimensions (H264 requirement)
+        m_width = width & ~1;
+        m_height = height & ~1;
+
+        // Initialize parameters
+        if (fn_x264_param_default_preset) {
+            fn_x264_param_default_preset(&m_param, "ultrafast", "zerolatency");
+        }
+
+        // Set encoder parameters
+        m_param.i_width = m_width;
+        m_param.i_height = m_height;
+        m_param.i_log_level = X264_LOG_NONE;
+        m_param.i_threads = 1;
+        m_param.i_frame_total = 0;
+        m_param.i_keyint_max = fps * 15;  // Keyframe every 15 seconds
+        m_param.i_bframe = 0;              // No B-frames for low latency
+        m_param.b_open_gop = 0;
+        m_param.i_fps_num = fps;
+        m_param.i_fps_den = 1;
+        m_param.i_csp = X264_CSP_I420;
+
+        // Rate control: CRF mode
+        m_param.rc.i_rc_method = X264_RC_CRF;
+        m_param.rc.f_rf_constant = (float)crf;
+
+        // Apply baseline profile for compatibility
+        if (fn_x264_param_apply_profile) {
+            fn_x264_param_apply_profile(&m_param, "baseline");
+        }
+
+        // Allocate pictures
+        m_picIn = (x264_picture_t*)calloc(1, sizeof(x264_picture_t));
+        m_picOut = (x264_picture_t*)calloc(1, sizeof(x264_picture_t));
+        if (!m_picIn || !m_picOut) {
+            close();
+            return false;
+        }
+
+        // Initialize input picture
+        if (fn_x264_picture_init) {
+            fn_x264_picture_init(m_picIn);
+        }
+
+        // Allocate picture buffer
+        if (fn_x264_picture_alloc) {
+            if (fn_x264_picture_alloc(m_picIn, X264_CSP_I420, m_width, m_height) < 0) {
+                close();
+                return false;
+            }
+        }
+
+        // Open encoder
+        m_encoder = fn_x264_encoder_open(&m_param);
+        if (!m_encoder) {
+            close();
+            return false;
+        }
+
+        return true;
+    }
+
+    void close() {
+        if (m_encoder && fn_x264_encoder_close) {
+            fn_x264_encoder_close(m_encoder);
+            m_encoder = nullptr;
+        }
+
+        if (m_picIn) {
+            if (fn_x264_picture_clean) {
+                fn_x264_picture_clean(m_picIn);
+            }
+            free(m_picIn);
+            m_picIn = nullptr;
+        }
+
+        if (m_picOut) {
+            free(m_picOut);
+            m_picOut = nullptr;
+        }
+
+        unloadLibrary();
+        m_width = m_height = 0;
+    }
+
+    /**
+     * Encode a frame
+     * @param bgra      Input BGRA image data
+     * @param bpp       Bits per pixel (24 or 32)
+     * @param stride    Bytes per row
+     * @param width     Image width
+     * @param height    Image height
+     * @param outData   Output: pointer to encoded H264 data
+     * @param outSize   Output: size of encoded data
+     * @param direction 1 = normal, -1 = vertical flip
+     * @return 0 on success, negative on error
+     */
+    int encode(uint8_t* bgra, uint8_t bpp, uint32_t stride,
+               uint32_t width, uint32_t height,
+               uint8_t** outData, uint32_t* outSize,
+               int direction = 1)
+    {
+        if (!m_encoder || !m_picIn || !fn_x264_encoder_encode) {
+            return -1;
+        }
+
+        // Check dimensions match
+        if ((int)(width & ~1) != m_width || (int)(height & ~1) != m_height) {
+            return -2;
+        }
+
+        // Convert BGRA to I420 directly into x264 picture planes
+        if (bpp == 32) {
+            convertBGRAtoI420(bgra, stride, direction,
+                              m_picIn->img.plane[0], m_picIn->img.i_stride[0],
+                              m_picIn->img.plane[1], m_picIn->img.i_stride[1],
+                              m_picIn->img.plane[2], m_picIn->img.i_stride[2]);
+        } else if (bpp == 24) {
+            convertRGB24toI420(bgra, stride, direction,
+                               m_picIn->img.plane[0], m_picIn->img.i_stride[0],
+                               m_picIn->img.plane[1], m_picIn->img.i_stride[1],
+                               m_picIn->img.plane[2], m_picIn->img.i_stride[2]);
+        } else {
+            return -3;
+        }
+
+        // Encode
+        x264_nal_t* pNal = nullptr;
+        int iNal = 0;
+        int encodeSize = fn_x264_encoder_encode(m_encoder, &pNal, &iNal, m_picIn, m_picOut);
+
+        if (encodeSize < 0) {
+            return -4;
+        }
+
+        if (encodeSize == 0 || !pNal) {
+            *outData = nullptr;
+            *outSize = 0;
+            return 0;
+        }
+
+        *outData = pNal->p_payload;
+        *outSize = encodeSize;
+        return 0;
+    }
+
+private:
+    // Library handle
+    void* m_x264Handle;
+
+    // Encoder state
+    x264_t* m_encoder;
+    x264_param_t m_param;
+    x264_picture_t* m_picIn;
+    x264_picture_t* m_picOut;
+    int m_width, m_height;
+
+    // x264 function pointers
+    void  (*fn_x264_param_default_preset)(x264_param_t*, const char*, const char*);
+    int   (*fn_x264_param_apply_profile)(x264_param_t*, const char*);
+    x264_t* (*fn_x264_encoder_open)(x264_param_t*);
+    void  (*fn_x264_encoder_close)(x264_t*);
+    int   (*fn_x264_encoder_encode)(x264_t*, x264_nal_t**, int*, x264_picture_t*, x264_picture_t*);
+    void  (*fn_x264_picture_init)(x264_picture_t*);
+    int   (*fn_x264_picture_alloc)(x264_picture_t*, int, int, int);
+    void  (*fn_x264_picture_clean)(x264_picture_t*);
+
+    void clearFunctionPointers() {
+        fn_x264_param_default_preset = nullptr;
+        fn_x264_param_apply_profile = nullptr;
+        fn_x264_encoder_open = nullptr;
+        fn_x264_encoder_close = nullptr;
+        fn_x264_encoder_encode = nullptr;
+        fn_x264_picture_init = nullptr;
+        fn_x264_picture_alloc = nullptr;
+        fn_x264_picture_clean = nullptr;
+    }
+
+    static void* TryLoadLibrary() {
+        // Try multiple library versions (newest first)
+        const char* libNames[] = {
+            "libx264.so",        // symlink (if exists)
+            "libx264.so.164",    // Ubuntu 24, Debian 12+
+            "libx264.so.163",
+            "libx264.so.162",
+            "libx264.so.161",
+            "libx264.so.160",
+            "libx264.so.159",
+            "libx264.so.157",
+            "libx264.so.155",    // Ubuntu 20
+            "libx264.so.152",
+            "libx264.so.148",    // older distros
+            nullptr
+        };
+
+        for (int i = 0; libNames[i]; i++) {
+            void* handle = dlopen(libNames[i], RTLD_LAZY);
+            if (handle) return handle;
+        }
+        return nullptr;
+    }
+
+    bool loadLibrary() {
+        m_x264Handle = TryLoadLibrary();
+        if (!m_x264Handle) {
+            return false;
+        }
+
+        // Load functions
+        fn_x264_param_default_preset = (decltype(fn_x264_param_default_preset))
+            dlsym(m_x264Handle, "x264_param_default_preset");
+
+        fn_x264_param_apply_profile = (decltype(fn_x264_param_apply_profile))
+            dlsym(m_x264Handle, "x264_param_apply_profile");
+
+        fn_x264_picture_init = (decltype(fn_x264_picture_init))
+            dlsym(m_x264Handle, "x264_picture_init");
+
+        fn_x264_picture_alloc = (decltype(fn_x264_picture_alloc))
+            dlsym(m_x264Handle, "x264_picture_alloc");
+
+        fn_x264_picture_clean = (decltype(fn_x264_picture_clean))
+            dlsym(m_x264Handle, "x264_picture_clean");
+
+        fn_x264_encoder_close = (decltype(fn_x264_encoder_close))
+            dlsym(m_x264Handle, "x264_encoder_close");
+
+        // x264_encoder_open has version suffix based on X264_BUILD
+        // Try common versions in order (newest first)
+        const char* openNames[] = {
+            "x264_encoder_open_164",
+            "x264_encoder_open_163",
+            "x264_encoder_open_162",
+            "x264_encoder_open_161",
+            "x264_encoder_open_160",
+            "x264_encoder_open_159",
+            "x264_encoder_open_157",
+            "x264_encoder_open_155",
+            "x264_encoder_open_152",
+            "x264_encoder_open_148",
+            nullptr
+        };
+
+        for (int i = 0; openNames[i]; i++) {
+            fn_x264_encoder_open = (decltype(fn_x264_encoder_open))
+                dlsym(m_x264Handle, openNames[i]);
+            if (fn_x264_encoder_open) {
+                fprintf(stderr, ">>> X264Encoder: found %s\n", openNames[i]);
+                break;
+            }
+        }
+
+        fn_x264_encoder_encode = (decltype(fn_x264_encoder_encode))
+            dlsym(m_x264Handle, "x264_encoder_encode");
+
+        // Check required functions
+        if (!fn_x264_encoder_open || !fn_x264_encoder_encode || !fn_x264_encoder_close ||
+            !fn_x264_param_default_preset || !fn_x264_picture_alloc) {
+            fprintf(stderr, "*** X264Encoder: missing functions - open=%p encode=%p close=%p preset=%p alloc=%p\n",
+                    (void*)fn_x264_encoder_open, (void*)fn_x264_encoder_encode,
+                    (void*)fn_x264_encoder_close, (void*)fn_x264_param_default_preset,
+                    (void*)fn_x264_picture_alloc);
+            unloadLibrary();
+            return false;
+        }
+
+        return true;
+    }
+
+    void unloadLibrary() {
+        if (m_x264Handle) {
+            dlclose(m_x264Handle);
+            m_x264Handle = nullptr;
+        }
+        clearFunctionPointers();
+    }
+
+    /**
+     * Convert BGRA to I420 (YUV 4:2:0 planar) directly into output planes
+     * Using ITU-R BT.601 coefficients
+     */
+    void convertBGRAtoI420(const uint8_t* bgra, int stride, int direction,
+                           uint8_t* yPlane, int yStride,
+                           uint8_t* uPlane, int uStride,
+                           uint8_t* vPlane, int vStride) {
+        int srcStride = stride;
+        int w = m_width;
+        int h = m_height;
+
+        // Direction: 1 = normal, -1 = flip vertically
+        int startY = (direction > 0) ? 0 : (h - 1);
+        int stepY = (direction > 0) ? 1 : -1;
+
+        // Y plane: full resolution
+        for (int j = 0; j < h; j++) {
+            int srcY = startY + j * stepY;
+            const uint8_t* srcRow = bgra + srcY * srcStride;
+            uint8_t* dstRow = yPlane + j * yStride;
+
+            for (int i = 0; i < w; i++) {
+                uint8_t b = srcRow[i * 4 + 0];
+                uint8_t g = srcRow[i * 4 + 1];
+                uint8_t r = srcRow[i * 4 + 2];
+                // Y = 0.257*R + 0.504*G + 0.098*B + 16
+                int y = ((66 * r + 129 * g + 25 * b + 128) >> 8) + 16;
+                dstRow[i] = (uint8_t)(y < 0 ? 0 : (y > 255 ? 255 : y));
+            }
+        }
+
+        // U/V planes: half resolution (2x2 block averaging)
+        int uvW = w / 2;
+        int uvH = h / 2;
+
+        for (int j = 0; j < uvH; j++) {
+            int srcY0 = startY + (j * 2) * stepY;
+            int srcY1 = startY + (j * 2 + 1) * stepY;
+            const uint8_t* row0 = bgra + srcY0 * srcStride;
+            const uint8_t* row1 = bgra + srcY1 * srcStride;
+
+            for (int i = 0; i < uvW; i++) {
+                // Average 4 pixels
+                int r = 0, g = 0, b = 0;
+
+                b += row0[(i*2+0)*4 + 0]; g += row0[(i*2+0)*4 + 1]; r += row0[(i*2+0)*4 + 2];
+                b += row0[(i*2+1)*4 + 0]; g += row0[(i*2+1)*4 + 1]; r += row0[(i*2+1)*4 + 2];
+                b += row1[(i*2+0)*4 + 0]; g += row1[(i*2+0)*4 + 1]; r += row1[(i*2+0)*4 + 2];
+                b += row1[(i*2+1)*4 + 0]; g += row1[(i*2+1)*4 + 1]; r += row1[(i*2+1)*4 + 2];
+
+                r >>= 2; g >>= 2; b >>= 2;
+
+                // U = -0.148*R - 0.291*G + 0.439*B + 128
+                int u = ((-38 * r - 74 * g + 112 * b + 128) >> 8) + 128;
+                // V = 0.439*R - 0.368*G - 0.071*B + 128
+                int v = ((112 * r - 94 * g - 18 * b + 128) >> 8) + 128;
+
+                uPlane[j * uStride + i] = (uint8_t)(u < 0 ? 0 : (u > 255 ? 255 : u));
+                vPlane[j * vStride + i] = (uint8_t)(v < 0 ? 0 : (v > 255 ? 255 : v));
+            }
+        }
+    }
+
+    /**
+     * Convert RGB24 to I420 (YUV 4:2:0 planar) directly into output planes
+     */
+    void convertRGB24toI420(const uint8_t* rgb, int stride, int direction,
+                            uint8_t* yPlane, int yStride,
+                            uint8_t* uPlane, int uStride,
+                            uint8_t* vPlane, int vStride) {
+        int srcStride = stride;
+        int w = m_width;
+        int h = m_height;
+
+        int startY = (direction > 0) ? 0 : (h - 1);
+        int stepY = (direction > 0) ? 1 : -1;
+
+        // Y plane
+        for (int j = 0; j < h; j++) {
+            int srcY = startY + j * stepY;
+            const uint8_t* srcRow = rgb + srcY * srcStride;
+            uint8_t* dstRow = yPlane + j * yStride;
+
+            for (int i = 0; i < w; i++) {
+                uint8_t r = srcRow[i * 3 + 0];
+                uint8_t g = srcRow[i * 3 + 1];
+                uint8_t b = srcRow[i * 3 + 2];
+                int y = ((66 * r + 129 * g + 25 * b + 128) >> 8) + 16;
+                dstRow[i] = (uint8_t)(y < 0 ? 0 : (y > 255 ? 255 : y));
+            }
+        }
+
+        // U/V planes
+        int uvW = w / 2;
+        int uvH = h / 2;
+
+        for (int j = 0; j < uvH; j++) {
+            int srcY0 = startY + (j * 2) * stepY;
+            int srcY1 = startY + (j * 2 + 1) * stepY;
+            const uint8_t* row0 = rgb + srcY0 * srcStride;
+            const uint8_t* row1 = rgb + srcY1 * srcStride;
+
+            for (int i = 0; i < uvW; i++) {
+                int r = 0, g = 0, b = 0;
+
+                r += row0[(i*2+0)*3 + 0]; g += row0[(i*2+0)*3 + 1]; b += row0[(i*2+0)*3 + 2];
+                r += row0[(i*2+1)*3 + 0]; g += row0[(i*2+1)*3 + 1]; b += row0[(i*2+1)*3 + 2];
+                r += row1[(i*2+0)*3 + 0]; g += row1[(i*2+0)*3 + 1]; b += row1[(i*2+0)*3 + 2];
+                r += row1[(i*2+1)*3 + 0]; g += row1[(i*2+1)*3 + 1]; b += row1[(i*2+1)*3 + 2];
+
+                r >>= 2; g >>= 2; b >>= 2;
+
+                int u = ((-38 * r - 74 * g + 112 * b + 128) >> 8) + 128;
+                int v = ((112 * r - 94 * g - 18 * b + 128) >> 8) + 128;
+
+                uPlane[j * uStride + i] = (uint8_t)(u < 0 ? 0 : (u > 255 ? 255 : u));
+                vPlane[j * vStride + i] = (uint8_t)(v < 0 ? 0 : (v > 255 ? 255 : v));
+            }
+        }
+    }
+};

macos/ScreenHandler.h

@@ -4,6 +4,7 @@
 #import <dispatch/dispatch.h>
 #import <IOKit/pwr_mgt/IOPMLib.h>
 #import "../client/IOCPClient.h"
+#import "../common/commands.h"  // QualityLevel, QualityProfile, ALGORITHM_*
 #include <vector>
 #include <atomic>
 #include <mutex>
@@ -33,11 +34,7 @@ struct BITMAPINFOHEADER_MAC {
 };
 #pragma pack(pop)
 
-// Screen algorithm constants
+// Algorithm constants from commands.h: ALGORITHM_GRAY, ALGORITHM_DIFF, ALGORITHM_H264, ALGORITHM_RGB565
-#define ALGORITHM_GRAY    0
-#define ALGORITHM_DIFF    1
-#define ALGORITHM_H264    2
-#define ALGORITHM_RGB565  3
 
 class ScreenHandler : public IOCPManager {
 public:

macos/ScreenHandler.mm

@@ -357,28 +357,40 @@ void ScreenHandler::applyQualityLevel(int8_t level, bool persist)
 {
     m_qualityLevel = level;
 
+    // TODO: persist to config file if needed
+    (void)persist;
+
     if (level == QUALITY_DISABLED) {
-        NSLog(@"Quality: Disabled");
+        // Disabled mode: keep current settings
+        NSLog(@"Quality: Disabled (keep current)");
         return;
     }
 
-    // Quality profiles: [FPS, Algorithm]
-    // H264 provides best compression for remote desktop
-    // Note: macOS uses slightly higher FPS than Windows for smoother experience
-    static const int profiles[QUALITY_COUNT][2] = {
-        {5,  ALGORITHM_GRAY},     // Level 0: Emergency (very low bandwidth)
-        {10, ALGORITHM_RGB565},   // Level 1: Low
-        {15, ALGORITHM_H264},     // Level 2: Medium (office work default)
-        {20, ALGORITHM_H264},     // Level 3: Good
-        {25, ALGORITHM_H264},     // Level 4: High
-        {30, ALGORITHM_H264},     // Level 5: Smooth
-    };
-
     if (level >= 0 && level < QUALITY_COUNT) {
-        m_maxFPS.store(profiles[level][0]);
+        // Get profile from commands.h (shared with Windows/Linux)
-        m_algorithm.store(profiles[level][1]);
+        const QualityProfile& profile = GetQualityProfile(level);
-        NSLog(@"Quality: Level=%d, FPS=%d, Algo=%d", level, profiles[level][0], profiles[level][1]);
+
+        // Apply FPS
+        m_maxFPS.store(profile.maxFPS);
+
+        // Apply algorithm (macOS supports all algorithms including H264 via VideoToolbox)
+        m_algorithm.store(profile.algorithm);
+
+        // Update H264 bitrate if applicable
+        if (profile.algorithm == ALGORITHM_H264 && profile.bitRate > 0) {
+            m_h264Bitrate = profile.bitRate * 1000;  // kbps -> bps
+        }
+
+        NSLog(@"Quality: Level=%d (%s), FPS=%d, Algo=%d, BitRate=%d kbps",
+              level,
+              level == QUALITY_ULTRA ? "Ultra" :
+              level == QUALITY_HIGH ? "High" :
+              level == QUALITY_GOOD ? "Good" :
+              level == QUALITY_MEDIUM ? "Medium" :
+              level == QUALITY_LOW ? "Low" : "Minimal",
+              profile.maxFPS, profile.algorithm, profile.bitRate);
     } else {
+        // Adaptive mode (level=-1): server adjusts dynamically
         NSLog(@"Quality: Adaptive mode");
     }
 }