如何在Unity3d平台下低延遲播放RTMP或RTSP流

随着VR類、遊戲類場景的快速發展，開發者對Unity3d低延遲的直播需求量越來越大，前兩年，大牛直播SDK釋出了Windows平台、Android平台和iOS平台的Unity3d RTMP和RTSP的播放，好多公司用起來體驗都非常好，以下介紹大概實作流程。

本文以Android平台為例，我們的實作：基于大牛直播SDK現有非常成熟的native RTMP和RTSP播放子產品，回調解碼後的原始資料，傳遞給Unity3d，實作相應的繪制即可，對應demo，可以參考 Github。

具體步驟如下：

Native RTSP或RTSP直播播放SDK回調RGB/YUV420/NV12等其中的一種未壓縮的圖像格式；
Unity3D建立相應的RGB/YUV420等Shader；

3.Unity3D從各個平台擷取圖像資料來填充紋理即可。

以Android平台為例，我們在原有接口基礎上，做了橋接接口，供Unity平台使用：

/// <summary>
/// Init
/// </summary>
public int NT_U3D_Init()
{
    return DANIULIVE_RETURN_OK;
}

/// <summary>
/// 開始
/// 傳回播放句柄
/// </summary>
public long NT_U3D_Open()
{
    if ( 0 != player_obj_.Call<int>("Init", java_obj_cur_activity_) )
    {
        return 0;
    }

    return player_obj_.Call<long>("Open");
}

/// <summary>
/// Register Game Object,用于消息傳遞
/// </summary>
public int NT_U3D_Set_Game_Object(long handle, string gameObjectName)
{
    return player_obj_.Call<int>("SetGameObject", handle, gameObjectName);
}

/// <summary>
/// 設定H.264解碼方式 false 軟體解碼 true 硬體解碼 預設為false
/// </summary>
/// <param name="isHwDecoder"></param>
public int NT_U3D_SetVideoDecoderMode(long handle, int isHwDecoder)
{
    return player_obj_.Call<int>("SetPlayerVideoHWDecoder", handle, isHwDecoder);
}

/// <summary>
/// 設定H.265 解碼方式 false 軟體解碼 true 硬體解碼 預設為false
/// </summary>
/// <param name="isHevcHwDecoder"></param>
public int NT_U3D_SetVideoHevcDecoderMode(long handle, int isHevcHwDecoder)
{
    return player_obj_.Call<int>("SetPlayerVideoHevcHWDecoder", handle, isHevcHwDecoder);
}

/// <summary>
/// 設定音頻輸出模式: if 0: 自動選擇; if with 1: audiotrack模式
/// </summary>
/// <param name="use_audiotrack"></param>
public int NT_U3D_SetAudioOutputType(long handle, int use_audiotrack)
{
    return player_obj_.Call<int>("SetAudioOutputType", handle, use_audiotrack);
}

/// <summary>
/// 設定播放端緩存大小, 預設200毫秒
/// </summary>
/// <param name="buffer"></param>
public int NT_U3D_SetBuffer(long handle, int buffer)
{
    return player_obj_.Call<int>("SetBuffer", handle, buffer);
}

/// <summary>
/// 接口可實時調用：設定是否實時靜音，1：靜音; 0: 取消靜音
/// </summary>
/// <param name="is_mute"></param>
public int NT_U3D_SetMute(long handle, int is_mute)
{
    return player_obj_.Call<int>("SetMute", handle, is_mute);
}

/// <summary>
/// 設定RTSP TCP模式, 1: TCP; 0: UDP
/// </summary>
/// <param name="is_using_tcp"></param>
public int NT_U3D_SetRTSPTcpMode(long handle, int is_using_tcp)
{
    return player_obj_.Call<int>("SetRTSPTcpMode", handle, is_using_tcp);
}

/// <summary>
/// 設定RTSP逾時時間, timeout機關為秒，必須大于0
/// </summary>
/// <param name="timeout"></param>
public int NT_U3D_SetRTSPTimeout(long handle, int timeout)
{
    return player_obj_.Call<int>("SetRTSPTimeout", handle, timeout);
}

/// <summary>
/// 設定RTSP TCP/UDP自動切換
/// NOTE: 對于RTSP來說，有些可能支援rtp over udp方式，有些可能支援使用rtp over tcp方式.
/// 為了友善使用，有些場景下可以開啟自動嘗試切換開關, 打開後如果udp無法播放，sdk會自動嘗試tcp, 如果tcp方式播放不了,sdk會自動嘗試udp.
/// </summary>
/// <param name="timeout"></param>
/// timeout：如果設定1的話, sdk将在tcp和udp之間嘗試切換播放，如果設定為0，則不嘗試切換.
public int NT_U3D_SetRTSPAutoSwitchTcpUdp(long handle, int is_auto_switch_tcp_udp)
{
    return player_obj_.Call<int>("SetRTSPAutoSwitchTcpUdp", handle, is_auto_switch_tcp_udp);
}

/// <summary>
/// 設定快速啟動該模式，
/// </summary>
/// <param name="is_fast_startup"></param>
public int NT_U3D_SetFastStartup(long handle, int is_fast_startup)
{
    return player_obj_.Call<int>("SetFastStartup", handle, is_fast_startup);
}

/// <summary>
/// 設定超低延遲模式 false不開啟 true開啟 預設false
/// </summary>
/// <param name="mode"></param>
public int NT_U3D_SetPlayerLowLatencyMode(long handle, int mode)
{
    return player_obj_.Call<int>("SetPlayerLowLatencyMode", handle, mode);
}

/// <summary>
/// 設定視訊垂直反轉
/// is_flip： 0: 不反轉, 1: 反轉
/// </summary>
/// <param name="is_flip"></param>
public int NT_U3D_SetFlipVertical(long handle, int is_flip)
{
    return player_obj_.Call<int>("SetFlipVertical", handle, is_flip);
}

/// <summary>
/// 設定視訊水準反轉
/// is_flip： 0: 不反轉, 1: 反轉
/// </summary>
/// <param name="is_flip"></param>
public int NT_U3D_SetFlipHorizontal(long handle, int is_flip)
{
    return player_obj_.Call<int>("SetFlipHorizontal", handle, is_flip);
}

/// <summary>
/// 設定順時針旋轉, 注意除了0度之外， 其他角度都會額外消耗性能
/// degress： 目前支援 0度，90度, 180度, 270度 旋轉
/// </summary>
/// <param name="degress"></param>
public int NT_U3D_SetRotation(long handle, int degress)
{
    return player_obj_.Call<int>("SetRotation", handle, degress);
}

/// <summary>
/// 設定是否回調下載下傳速度
/// is_report: if 1: 上報下載下傳速度, 0: 不上報.
/// report_interval: 上報間隔，以秒為機關，>0.
/// </summary>
/// <param name="is_report"></param>
/// <param name="report_interval"></param>
public int NT_U3D_SetReportDownloadSpeed(long handle, int is_report, int report_interval)
{
    return player_obj_.Call<int>("SetReportDownloadSpeed", handle, is_report, report_interval);
}

/// <summary>
/// 設定是否需要在播放或錄像過程中快照
/// </summary>
/// <param name="is_save_image"></param>
public int NT_U3D_SetSaveImageFlag(long handle, int is_save_image)
{
    return player_obj_.Call<int>("SetSaveImageFlag", handle, is_save_image);
}

/// <summary>
/// 播放或錄像過程中快照
/// </summary>
/// <param name="imageName"></param>
public int NT_U3D_SaveCurImage(long handle, string imageName)
{
    return player_obj_.Call<int>("SaveCurImage", handle, imageName);
}

/// <summary>
/// 播放或錄像過程中，快速切換url
/// </summary>
/// <param name="uri"></param>
public int NT_U3D_SwitchPlaybackUrl(long handle, string uri)
{
    return player_obj_.Call<int>("SwitchPlaybackUrl", handle, uri);
}

/// <summary>
/// 建立錄像存儲路徑
/// </summary>
/// <param name="path"></param>
public int NT_U3D_CreateFileDirectory(string path)
{
    return player_obj_.Call<int>("CreateFileDirectory", path);
}

/// <summary>
/// 設定錄像存儲路徑
/// </summary>
/// <param name="path"></param>
public int NT_U3D_SetRecorderDirectory(long handle, string path)
{
    return player_obj_.Call<int>("SetRecorderDirectory", handle, path);
}

/// <summary>
/// 設定單個錄像檔案大小
/// </summary>
/// <param name="size"></param>
public int NT_U3D_SetRecorderFileMaxSize(long handle, int size)
{
    return player_obj_.Call<int>("SetRecorderFileMaxSize", handle, size);
}

/// <summary>
/// 設定錄像時音頻轉AAC編碼的開關
/// aac比較通用，sdk增加其他音頻編碼(比如speex, pcmu, pcma等)轉aac的功能.
/// 注意: 轉碼會增加性能消耗
/// </summary>
/// <param name="is_transcode"></param>
/// is_transcode：設定為1的話，如果音頻編碼不是aac，則轉成aac，如果是aac，則不做轉換. 設定為0的話，則不做任何轉換. 預設是0.
public int NT_U3D_SetRecorderAudioTranscodeAAC(long handle, int is_transcode)
{
    return player_obj_.Call<int>("SetRecorderAudioTranscodeAAC", handle, is_transcode);
}

/// <summary>
/// 設定播放路徑
/// </summary>
public int NT_U3D_SetUrl(long handle, string url)
{
    return player_obj_.Call<int>("SetUrl", handle, url);
}

/// <summary>
/// 開始播放
/// </summary>
public int NT_U3D_StartPlay(long handle)
{
    return player_obj_.Call<int>("StartPlay", handle);
}

/// <summary>
/// 擷取YUV資料
/// </summary>
public AndroidJavaObject NT_U3D_GetVideoFrame(long handle)
{
    return player_obj_.Call<AndroidJavaObject>("GetVideoFrame", handle);
}

/// <summary>
/// 停止播放
/// </summary>
public int NT_U3D_StopPlay(long handle)
{
    return player_obj_.Call<int>("StopPlay", handle);
}

/// <summary>
/// 開始錄像
/// </summary>
public int NT_U3D_StartRecorder(long handle)
{
    return player_obj_.Call<int>("StartRecorder", handle);
}

/// <summary>
/// 停止錄像
/// </summary>
public int NT_U3D_StopRecorder(long handle)
{
    return player_obj_.Call<int>("StopRecorder", handle);
}

/// <summary>
/// 關閉播放
/// </summary>
public int NT_U3D_Close(long handle)
{
    return player_obj_.Call<int>("Close", handle);
}

/// <summary>
/// UnInit Player
/// </summary>
public int NT_U3D_UnInit()
{
    return DANIULIVE_RETURN_OK;
}

Event傳遞，我們在unity3d裡面解析相應的字串即可：

///

/// android 傳遞過來 code
/// </summary>
/// <param name="code"></param>
public void onNTSmartEvent(string param)
{
    if (!param.Contains(","))
    {
        Debug.Log("[onNTSmartEvent] android傳遞參數錯誤");
        return;
    }

   string[] strs = param.Split(',');

   string player_handle =strs[0];
   string code = strs[1];
   string param1 = strs[2];
   string param2 = strs[3];
   string param3 = strs[4];
   string param4 = strs[5];
    
   Debug.Log("[onNTSmartEvent] code: 0x" + Convert.ToString(Convert.ToInt32(code), 16));

    switch (Convert.ToInt32(code))
    {
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_STARTED:
            Debug.Log("開始。。");
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_CONNECTING:
            Debug.Log("連接配接中。。");
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_CONNECTION_FAILED:
            Debug.Log("連接配接失敗。。");
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_CONNECTED:
            Debug.Log("連接配接成功。。");
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_DISCONNECTED:
            Debug.Log("連接配接斷開。。");
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_STOP:
            Debug.Log("停止播放。。");
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_RESOLUTION_INFO:
            Debug.Log("分辨率資訊: width: " + Convert.ToInt32(param1) + ", height: " + Convert.ToInt32(param2));
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_NO_MEDIADATA_RECEIVED:
            Debug.Log("收不到媒體資料，可能是url錯誤。。");
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_SWITCH_URL:
            Debug.Log("切換播放URL。。");
            break;

        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_CAPTURE_IMAGE:
            Debug.Log("快照: " + param1 + " 路徑：" + param3);

            if (Convert.ToInt32(param1) == 0)
            {
                Debug.Log("截取快照成功。.");
            }
            else
            {
                Debug.Log("截取快照失敗。.");
            }
            break;

        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_RECORDER_START_NEW_FILE:
            Debug.Log("[record]開始一個新的錄像檔案 : " + param3);
            break;
        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_ONE_RECORDER_FILE_FINISHED:
            Debug.Log("[record]已生成一個錄像檔案 : " + param3);
            break;

        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_START_BUFFERING:
            Debug.Log("Start_Buffering");
            break;

        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_BUFFERING:
            Debug.Log("Buffering: " + Convert.ToInt32(param1));
            break;

        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_STOP_BUFFERING:
            Debug.Log("Stop_Buffering");
            break;

        case EVENTID.EVENT_DANIULIVE_ERC_PLAYER_DOWNLOAD_SPEED:
            Debug.Log("download_speed:" + param1 + "Byte/s" + ", "
                    + (Convert.ToInt32(param1) * 8 / 1000) + "kbps" + ", " + (Convert.ToInt32(param1) / 1024)
                    + "KB/s");
            break;
    }

}

開始播放：

public void Play()
{
    if (is_running)
    {
        Debug.Log("已經在播放。。");   
        return;
    }

    //擷取輸入框的url
    string url = input_url_.text.Trim();

    if (!url.StartsWith("rtmp://") && !url.StartsWith("rtsp://"))
    {
        videoUrl = "rtmp://202.69.69.180:443/webcast/bshdlive-pc";
    }
    else
    {
        videoUrl = url;
    }

    OpenPlayer();

    if ( player_handle_ == 0 )
        return;

    NT_U3D_Set_Game_Object(player_handle_, game_object_);

    NT_U3D_SetUrl(player_handle_, videoUrl);

    /* ++ 播放前參數配置可加在此處 ++ */
    int is_using_tcp = 0;        //TCP/UDP模式設定
    NT_U3D_SetRTSPTcpMode(player_handle_, is_using_tcp);

    int is_report = 0;
    int report_interval = 1;
    NT_U3D_SetReportDownloadSpeed(player_handle_, is_report, report_interval);  //下載下傳速度回調

    NT_U3D_SetBuffer(player_handle_, play_buffer_time_);                        //設定buffer time

    NT_U3D_SetPlayerLowLatencyMode(player_handle_, is_low_latency_ ? 1 : 0);    //設定是否啟用低延遲模式

    NT_U3D_SetMute(player_handle_, is_mute_ ? 1 : 0);                           //是否啟動播放的時候靜音

    NT_U3D_SetVideoDecoderMode(player_handle_, is_hw_decode_ ? 1 : 0);          //設定H.264軟硬解模式

    NT_U3D_SetVideoHevcDecoderMode(player_handle_, is_hw_decode_ ? 1 : 0);          //設定H.265軟硬解模式

    int is_fast_startup = 1;
    NT_U3D_SetFastStartup(player_handle_, is_fast_startup);                     //設定快速啟動模式

    int rtsp_timeout = 10;
    NT_U3D_SetRTSPTimeout(player_handle_, rtsp_timeout);                        //設定RTSP逾時時間

    int is_auto_switch_tcp_udp = 1;
    NT_U3D_SetRTSPAutoSwitchTcpUdp(player_handle_, is_auto_switch_tcp_udp);    //設定TCP/UDP模式自動切換
    /* -- 播放前參數配置可加在此處 -- */

    int flag = NT_U3D_StartPlay(player_handle_);

    if (flag  == DANIULIVE_RETURN_OK)
    {
        is_need_get_frame_ = true;
        Debug.Log("播放成功");
    }
    else
    {
        is_need_get_frame_ = false;
        Debug.LogError("播放失敗");
    }

    is_running = true;  
}

開始播放後，native子產品，回調yuv/rgb資料，unity3d子產品，做相應的繪制處理即可。

private void Update()
{
    if (!is_need_get_frame_)
        return;

    if (player_handle_ == 0)
        return;

    AndroidJavaObject u3d_video_frame_obj = NT_U3D_GetVideoFrame(player_handle_);

    if (u3d_video_frame_obj == null)
        return;

    VideoFrame converted_video_frame = ConvertToVideoFrame(u3d_video_frame_obj);

    if (converted_video_frame == null)
        return;

    if ( !is_need_init_texture_)
    {
        if (converted_video_frame.width_ != video_width_
            || converted_video_frame.height_ != video_height_
            || converted_video_frame.y_stride_ != y_row_bytes_
            || converted_video_frame.u_stride_ != u_row_bytes_
            || converted_video_frame.v_stride_ != v_row_bytes_)
        {
            is_need_init_texture_ = true;
        }
    }

    if (is_need_init_texture_)
    {
        if (InitYUVTexture(converted_video_frame))
        {
            is_need_init_texture_ = false;
        }
    }

    UpdateYUVTexture(converted_video_frame);

    converted_video_frame = null;
}

關閉播放：

private void ClosePlayer()
{
    is_need_get_frame_ = false;
    is_need_init_texture_ = false;

    int flag = NT_U3D_StopPlay(player_handle_);
    if (flag == DANIULIVE_RETURN_OK)
    {
        Debug.Log("停止成功");
    }
    else
    {
        Debug.LogError("停止失敗");
    }

    flag = NT_U3D_Close(player_handle_);
    if (flag == DANIULIVE_RETURN_OK)
    {
        Debug.Log("關閉成功");
    }
    else
    {
        Debug.LogError("關閉失敗");
    }

    player_handle_ = 0;

    NT_U3D_UnInit();

    is_running = false;
}

以上是大概的實作流程，Unity環境下，實際測試時延，和 native直播子產品相差無幾，都是毫秒級延遲。Windows平台和iOS平台也是如此。

如何在Unity3d平台下低延遲播放RTMP或RTSP流

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