​技术背景

我们在做Windows平台RTMP推送、轻量级RTSP服务录像模块的时候，部分开发者抱怨路径无法设置中文，只能设置为英文。

以C#的接口为例，早期的设计如下：

 /*
* 设置本地录像目录, 必须是英文目录，否则会失败
*/
[DllImport(@"SmartPublisherSDK.dll")]
public static extern UInt32 NT_PB_SetRecorderDirectory(IntPtr handle, [MarshalAs(UnmanagedType.LPStr)] String dir, IntPtr pReserve);

考虑到一些场景的特殊性，可能需要中文路径，我们设计的接口如下：

/*
 * 设置本地录像目录, 支持中文目录, 需要设置宽字符，比如L"D:\\xxx\\gg"
 */
[DllImport(@"SmartPublisherSDK.dll")]
public static extern UInt32 NT_PB_SetRecorderDirectoryW(IntPtr handle, [MarshalAs(UnmanagedType.LPWStr)]String dir, IntPtr pReserve);

调用如下，以调用开始录像、暂停录像、停止录像为例，调用逻辑如下，可以看到除了中文路径诉求，录像模块还可以添加前缀、添加文字、水印：

public bool StartRecorder()
{
    if (is_empty_handle() || is_recording())
        return false;

    //string edit_rec_dir = "D:\\dntest";
    string edit_rec_dir = "D:\\推送端录像";

    if (String.IsNullOrEmpty(edit_rec_dir))
    {
        Console.WriteLine("请设置录像目录");
        return false;
    }

    uint ret = NTSmartPublisherSDK.NT_PB_SetRecorderDirectoryW(handle_, edit_rec_dir, IntPtr.Zero);

    if (NTBaseCodeDefine.NT_ERC_OK != ret)
    {
        try_close_handle();
        return false;
    }

    uint rec_max_file_size = 512 * 1024;
    NTSmartPublisherSDK.NT_PB_SetRecorderFileMaxSize(handle_, rec_max_file_size);

    NT_PB_RecorderFileNameRuler rec_name_ruler = new NT_PB_RecorderFileNameRuler();

    String rec_file_name_prefix_ = "transcode-rec";
    rec_name_ruler.file_name_prefix_ = rec_file_name_prefix_.ToString();
    rec_name_ruler.append_date_ = 1;
    rec_name_ruler.append_time_ = 1;

    NTSmartPublisherSDK.NT_PB_SetRecorderFileNameRuler(handle_, ref rec_name_ruler);

    if (NTBaseCodeDefine.NT_ERC_OK != NTSmartPublisherSDK.NT_PB_StartRecorder(handle_, IntPtr.Zero))
    {
        try_close_handle();
        return false;
    }

    shared_lock_.EnterWriteLock();
    try
    {
        handle_reference_count_++;
        is_recording_ = true;
    }
    finally
    {
        shared_lock_.ExitWriteLock();
    }

    return true;
}

public UInt32 PauseRecorder(bool is_pause)
{
    if (is_empty_handle() || !is_recording())
        return NTBaseCodeDefine.NT_ERC_FAILED;

    UInt32 ret = NTBaseCodeDefine.NT_ERC_OK;

    if (is_pause)
    {
        ret = NTSmartPublisherSDK.NT_PB_PauseRecorder(handle_, 1);
        if ((UInt32)NT.NTSmartPublisherDefine.NT_PB_E_ERROR_CODE.NT_ERC_PB_NEED_RETRY == ret)
        {
            Console.WriteLine("暂停录像失败, 请重新尝试!");
            return ret;
        }
        else if (NTBaseCodeDefine.NT_ERC_OK == ret)
        {
            //btn_pause_rec.Text = "恢复录像";
        }
    }
    else
    {
        ret = NTSmartPublisherSDK.NT_PB_PauseRecorder(handle_, 0);
        if ((UInt32)NT.NTSmartPublisherDefine.NT_PB_E_ERROR_CODE.NT_ERC_PB_NEED_RETRY == ret)
        {
            Console.WriteLine("恢复录像失败, 请重新尝试!");
            return ret;
        }
        else if (NTBaseCodeDefine.NT_ERC_OK == ret)
        {
            //btn_pause_rec.Text = "暂停录像";
        }
    }

    return ret;
}

public void StopRecorder()
{
    if (is_empty_handle() || !is_recording())
        return;

    shared_lock_.EnterWriteLock();
    try
    {
        is_recording_ = false;
        handle_reference_count_--;
    }
    finally
    {
        shared_lock_.ExitWriteLock();
    }

    NTSmartPublisherSDK.NT_PB_StopRecorder(handle_);
    try_close_handle();
}

开始录像和录像完成后，提示如下：

private void PbEventCallBack(UInt32 event_id,
    Int64 param1,
    Int64 param2,
    UInt64 param3,
    UInt64 param4,
    [MarshalAs(UnmanagedType.LPStr)] String param5,
    [MarshalAs(UnmanagedType.LPStr)] String param6,
    IntPtr param7)
{
    String event_log = "";

    switch (event_id)
    {
        ......
        case (uint)NTSmartPublisherDefine.NT_PB_E_EVENT_ID.NT_PB_E_EVENT_ID_RECORDER_START_NEW_FILE:
            event_log = " start new recorder file";

            byte[] utf8_bytes = Encoding.Default.GetBytes(param5);
            byte[] default_bytes = Encoding.Convert(Encoding.UTF8, Encoding.Default, utf8_bytes);
            String file_name = Encoding.Default.GetString(default_bytes);

            if (!String.IsNullOrEmpty(file_name))
            {
                event_log = event_log + " file name:" + file_name;
            }
            break;

        case (uint)NTSmartPublisherDefine.NT_PB_E_EVENT_ID.NT_PB_E_EVENT_ID_ONE_RECORDER_FILE_FINISHED:
            event_log = " finish recorder file";
            byte[] finished_utf8_bytes = Encoding.Default.GetBytes(param5);
            byte[] finished_default_bytes = Encoding.Convert(Encoding.UTF8, Encoding.Default, finished_utf8_bytes);
            String finished_file_name = Encoding.Default.GetString(finished_default_bytes);

            if (!String.IsNullOrEmpty(finished_file_name))
            {
                event_log = event_log + " file name:" + finished_file_name;
            }
            break;

        .......

        default:
            break;
    }

    EventGetPublisherEventMsg(event_log);
}

总结

Windows平台RTMP推送、轻量级RTSP服务配套的录像模块，除了设置录像保存路径外、还可以设置录像文件前缀、是不是添加日期、时间等，还有就是单个录像文件大小，超过这个大小后，会自动切换到下个文件。