Windows平台RTMP推送|轻量级RTSP服务录像模块如何支持中文路径？

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);
        }