The VideoLAN Forums

Posted: **22 Sep 2023 14:37**

Hello,

Reposting my post from stackoverflow (I hope it is an acceptable pratice)

https://stackoverflow.com/questions/771 ... -app-java
Viewing a rtsp stream on my libVLC, I get 1s of delay. I tried to use all the possible options to be set in libVLC I could find to reduce the delay.

I have a rtsp server on my host machine that streams in RTSP with the following code

Code: Select all

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

Code: Select all

[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

Code: Select all

            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();

I have this version of the lib:

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

Any brilliant idea on how to debug this, or what to change to reduce the delay?
Thanks a lot!

I tried to visualize the stream on a separate client on the same devide (Qgroundcontrol) and I have no visible delay.

EDIT: It turns out that remove the -F frame rate options from the server decreases the delay but it is still pretty big, around 600ms

The VideoLAN Forums

Find the best option to minimize the lag of libVLC Android app java

Find the best option to minimize the lag of libVLC Android app java