C# 視訊監控系列（11）：H264 播放器核心 API 封裝

本文提供 HikPlayM4.dll 核心播放功能的 C# P/Invoke 封裝類別，涵蓋檔案開啟、播放控制、音訊、畫質、截圖、回調註冊等常用 API，供系列後續文章直接引用。

封裝類別結構

using System;
using System.Runtime.InteropServices;

namespace HikPlayer
{
    public static class HikPlayM4
    {
        // 播放通道常數
        public const int MAX_PORT = 16;

        // 視訊格式枚舉
        public enum VideoFormat
        {
            vdfYUV422Planar = 0,
            vdfRGB16 = 1,
            vdfRGB24 = 2,
            vdfRGB32 = 3,
            vdfYUV420Planar = 4
        }

        // 核心 API 宣告
        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_OpenFile(int nPort, string sFileName);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_Play(int nPort, IntPtr hWnd);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_Stop(int nPort);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_Pause(int nPort, bool bPause);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_Fast(int nPort);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_Slow(int nPort);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_SetPlayPos(int nPort, double dPos); // 0.0~1.0

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_PlaySound(int nPort);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_StopSound();

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_SetVolume(int nPort, int nVolume); // 0~0xFFFF

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_GetPictureSize(int nPort, out int nWidth, out int nHeight);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_SetOverlayMode(int nPort, bool bEnable, int nColorKey);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_SetDisplayCallBack(int nPort, DisplayCBFun fDisplayCBFun);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PLayM4_ConvertToBmpFile(IntPtr pBuf, int nSize, int nWidth, int nHeight, int nType, string sFileName);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_CloseFile(int nPort);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_RealeseDDraw();

        [DllImport("HikPlayM4.dll")]
        public static extern int Hik_PlayM4_GetLastError(int nPort);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_ThrowBFrameNum(int nPort, int nNum);

        [DllImport("HikPlayM4.dll")]
        public static extern bool Hik_PlayM4_SetPicQuality(int nPort, bool bHighQuality);

        // 回調委派定義
        public delegate void DisplayCBFun(int nPort, IntPtr pBuf, int nSize, int nWidth, int nHeight, int nStamp, int nType, int nReceaved);

        // 視窗訊息常數
        public const int WM_FILE_END = 0x0400 + 100;
        public const int WM_ENC_CHANGE = 0x0400 + 101;
    }
}

使用注意事項

• 所有 API 回傳 bool，false 表示失敗，可呼叫 GetLastError 取得錯誤碼。
• nPort 範圍 0~15，同一時間每個 Port 只能播放一個來源。
• 回調委派 必須聲明為類別成員，防止被 GC 回收導致存取違規。
• SetDisplayCallBack 設為 null 可停止回調。
• 播放結束務必呼叫 CloseFile、Stop、RealeseDDraw 釋放資源。

後續維護

本封裝僅包含播放器核心功能，隨系列文章推進會持續補充（如解碼回調、音訊回調、流播放等）。建議專案中建立獨立 HikPlayer 專案引用，便於維護與單元測試。