找到最小化 libVLC Android 应用程序 java 延迟的最佳选项

Question

在我的 libVLC 上查看 rtsp 流时，出现 1 秒的延迟。 我尝试使用 libVLC 中设置的所有可能选项来减少延迟。

我的主机上有一个 rtsp 服务器，它使用以下代码在 RTSP 中进行流传输

/v4l2rtspserver/v4l2rtspserver -W 320 -H 240 -F 30 -P 8554 $mycam 

输出：

[NOTICE] /v4l2rtspserver/main.cpp:269
    Version: 0.3.6-3-g233b631 live555 version:2022.10.01
[NOTICE] /v4l2rtspserver/src/V4l2RTSPServer.cpp:37
    Create V4L2 Source.../dev/video0
[NOTICE] /v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:133
    driver:uvcvideo capabilities:84200001 mandatory:4000001
[NOTICE] /v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:136
    /dev/video0 support capture
[NOTICE] /v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:139
    /dev/video0 support streaming
[ERROR] /v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:212
    /dev/video0: Cannot set pixelformat to:H264 format is:YUYV
[NOTICE] /v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:225
    /dev/video0:MJPG size:320x240 bufferSize:153600
[NOTICE] /v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:246
    fps:1/30
[NOTICE] /v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:247
    nbBuffer:0
[NOTICE] /v4l2rtspserver/libv4l2cpp/src/V4l2MmapDevice.cpp:49
    Device /dev/video0
[NOTICE] /v4l2rtspserver/libv4l2cpp/src/V4l2MmapDevice.cpp:73
    Device /dev/video0 nb buffer:10
[NOTICE] /v4l2rtspserver/src/V4l2RTSPServer.cpp:62
    Create Source .../dev/video0
[NOTICE] /v4l2rtspserver/inc/BaseServerMediaSubsession.h:49
    format:video/JPEG
[NOTICE] /v4l2rtspserver/inc/V4l2RTSPServer.h:234
    Play this stream using the URL "rtsp://XXXXXXX:8554/unicast"
[NOTICE] /v4l2rtspserver/src/V4L2DeviceSource.cpp:96
handleCmd_SETUP:SETUP rtsp://192.168.5.1:8554/unicast/track1 RTSP/1.0
CSeq: 4
User-Agent: LibVLC/4.0.0-dev (LIVE555 Streaming Media v2022.07.14)
Transport: RTP/AVP;unicast;client_port=57666-57667

String rtspStreamUrl;
            Resources res = getResources();

            rtspStreamUrl = preferences.getString("rtspStreamUrl", getResources().getString(R.string.Default_RtspStreamUrl)) ;
            ///
            ArrayList<String> options = new ArrayList<>();
            options.add("-vvv");
            options.add("--low-delay");
            options.add("--network-caching=100");
            //options.add("--file-caching=100");
            //options.add("--sub-track=0");
            //options.add("--rtsp-tcp");

            LibVLC libVLC = new LibVLC(this, options);

            // VLC's MediaPlayer
            org.videolan.libvlc.MediaPlayer vlcMediaPlayer = new org.videolan.libvlc.MediaPlayer(libVLC);

            SurfaceView surfaceView = findViewById(R.id.surface_view);
            FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT);
            surfaceView.setLayoutParams(params);

            vlcMediaPlayer.getVLCVout().setVideoView(surfaceView);
            vlcMediaPlayer.getVLCVout().attachViews();

            Media media = new Media(libVLC, Uri.parse(rtspStreamUrl));

            ///
            media.setHWDecoderEnabled(true, true);
            media.addOption(":network-caching=250");//golden was 250
            media.addOption(":clock-jitter=0");//golden was 0
            media.addOption(":clock-synchro=0");
            media.addOption(":no-dr");
            media.addOption(":drop-late-frames");
            media.addOption(":skip-frames");
            media.addOption(":live-caching=50");  // for example, to set it to 50ms
            ///

            vlcMediaPlayer.setMedia(media);
            media.release();

            DisplayMetrics metrics = new DisplayMetrics();
            getWindowManager().getDefaultDisplay().getMetrics(metrics);
            int screenHeight = metrics.heightPixels;
            int screenWidth = metrics.widthPixels;

            vlcMediaPlayer.getVLCVout().setWindowSize(screenWidth, screenHeight);  // This sets the dimensions VLC will use
            vlcMediaPlayer.setAspectRatio("16:9");  // or whatever aspect ratio you want, e.g., "4:3"

            vlcMediaPlayer.play();

我有这个版本的库：

implementation 'org.videolan.android:libvlc-all:4.0.0-eap11' 

关于如何调试这个问题，或者改变什么来减少延迟，有什么好主意吗？

我尝试在同一设备（Qgroundcontrol）上的单独客户端上可视化流，并且没有明显的延迟。

编辑： 事实证明，从服务器中删除 -F 帧速率选项会减少延迟，但延迟仍然很大，大约 600 毫秒

Answer 1

我注意到 VLC 的第三个版本比第四个版本好得多。您可以尝试安装不同版本并进行比较。 😉