I'm trying to realize a real time streaming using gstreamer as server over pure RTP (no RTSP) using a sdp file with a delay from server to client < 500ms. Test server has tested using
gst-launch-1.0 -v v4l2src ! video/x-raw,width=640,height=480,framerate=30/1 ! x264enc tune=zerolatency threads=0 bitrate=500 speed-preset=ultrafast ! rtph264pay pt=96 config-interval=1 ! udpsink host=X.X.X.X port=X
If I try to receive it from a gstreamer client using gst-launch I achieve no delay (using two different devices on network), also I'm able to achieve the same using vlc as client, reading the sdp file and with file-caching >= 1500ms.
My problem is that I need an android client. I'm trying to use LibVLC for Android but with same options I can't achieve a delay < 2s.
LibVLC code for Android, where MediaPlayer and Media are part of org.videolan.libvlc:
ArrayList<String> options = new ArrayList<String>();
options.add("--file-caching=2000");
mLibVLC = new LibVLC(options);
mLibVLC.setOnHardwareAccelerationError(this);
mHolder.setKeepScreenOn(true);
// Create media player
mMediaPlayer = new MediaPlayer(mLibVLC);
mMediaPlayer.setEventListener(mPlayerListener);
mSurface = (SurfaceView) findViewById(R.id.surfaceView);
mHolder = mSurface.getHolder();
// Set up video output
final IVLCVout vout = mMediaPlayer.getVLCVout();
vout.setVideoView(mSurface);
vout.setWindowSize(640, 480);
vout.addCallback(this);
vout.attachViews();
Media m = new Media(mLibVLC, media);
mMediaPlayer.setMedia(m);
mMediaPlayer.play();
I also tried other options as --clock-synchro --clock-jitter etc... On startup it seems that needs about 2s for buffering and these seconds delay the whole streaming. There is a way to reduce the delay like in the standard client, or if exists an alternative android client?
SOLUTION:
Finally I got it works with a delay ≈200ms. I investigated LibVLC and Media objects more and I founded that I can set local Media options and hardware acceleration. I setted network-caching on low value (contrary of VLC desktop client) clock-synchro, clock-jitter, futhermore I used a global option for scaling algorithm to Fast Bilinear, that is enough for my activity. Below the updated code:
ArrayList<String> options = new ArrayList<String>();
options.add("--aout=none");
options.add("--swscale-mode=0");
mLibVLC = new LibVLC(options);
mLibVLC.setOnHardwareAccelerationError(this);
mHolder.setKeepScreenOn(true);
// Create media player
mMediaPlayer = new MediaPlayer(mLibVLC);
mMediaPlayer.setEventListener(mPlayerListener);
// Set up video output
final IVLCVout vout = mMediaPlayer.getVLCVout();
vout.setVideoView(mSurface);
vout.setWindowSize(640, 480);
vout.addCallback(this);
vout.attachViews();
Media m = new Media(mLibVLC, media);
m.setHWDecoderEnabled(true, false);
m.addOption(":network-caching=150");
m.addOption(":clock-jitter=0");
m.addOption(":clock-synchro=0");
mMediaPlayer.setMedia(m);
mMediaPlayer.play();
Enabling hardware acceleration on Media it is automatically set file-caching and network-caching to 1500ms, so I overwrote the network-caching option, in this case file-caching is not used. Further investigations could be done on clock-jitter option for better optimization.
