C# 視訊監控系列（九）：伺服器端資料擷取與 H.264 錄影實作（三）

核心邏輯說明

1. StartCap/StopCap 按鈕事件分別寫入檔案頭與結束碼 (0x00000002)，關鍵在 _write 函式。
2. 回調函式 StreamDirectReadCallback 邊寫入記憶體邊寫入檔案，輸出 .264 檔。frameType == PktSysHeader 表示檔案頭，僅出現一次。
3. gFileHandle 為檔案指標陣列，檔案開啟後回調持續寫入資料。

C# 實作程式碼

// 儲存檔案頭
byte[] FileHeader;
int FileHeaderLen;
volatile int CaptureState;

private void btnStart_Click(object sender, EventArgs e)
{
    using (FileStream fs = new FileStream(@"C:\hik.264", FileMode.Create))
    {
        BinaryWriter bw = new BinaryWriter(fs);
        bw.Write(FileHeader);
        bw.Flush();
    }
    CaptureState = 1;
}

uint endCode = 0x00000002;
private void btnStop_Click(object sender, EventArgs e)
{
    CaptureState = 0;
    using (FileStream fs = new FileStream(@"C:\hik.264", FileMode.Append))
    {
        BinaryWriter bw = new BinaryWriter(fs);
        bw.Write(endCode);
    }
}

public int STREAM_DIRECT_READ_CALLBACK1(int channelNum, IntPtr DataBuf, int Length, FrameType_t frameType, IntPtr context)
{
    int status = 0;
    if (frameType > 0)
    {
        if (frameType == FrameType_t.PktSysHeader)
        {
            FileHeader = new byte[Length];
            Marshal.Copy(DataBuf, FileHeader, 0, Length);
            FileHeaderLen = Length;
        }
        if (frameType == FrameType_t.PktIFrames || frameType == FrameType_t.PktSubIFrames)
            status = 1;
        else
            status = 0;
        if (frameType == FrameType_t.PktMotionDetection || frameType == FrameType_t.PktOrigImage)
            return 0;
    }
    if (Length == 0) return 0;

    if (frameType == FrameType_t.PktAudioFrames)
    {
        WriterVideoCapture(Length, DataBuf);
        HikServer.MP4_ServerWriteDataEx(channelNum, DataBuf, Length, (int)frameType, status, 0);
    }
    else if (frameType == FrameType_t.PktSubIFrames || frameType == FrameType_t.PktSubPFrames ||
             frameType == FrameType_t.PktSubBBPFrames || frameType == FrameType_t.PktSubSysHeader)
    {
        HikServer.MP4_ServerWriteDataEx(channelNum, DataBuf, Length, (int)frameType, status, 1);
    }
    else
    {
        WriterVideoCapture(Length, DataBuf);
        HikServer.MP4_ServerWriteDataEx(channelNum, DataBuf, Length, (int)frameType, status, 0);
    }
    return 0;
}

private void WriterVideoCapture(int length, IntPtr dataBuf)
{
    if (CaptureState == 1)
    {
        using (FileStream fs = new FileStream(@"C:\hik.264", FileMode.Append))
        {
            BinaryWriter bw = new BinaryWriter(fs);
            byte[] byteBuf = new byte[length];
            Marshal.Copy(dataBuf, byteBuf, 0, length);
            bw.Write(byteBuf);
            bw.Flush();
        }
    }
}