Revision as of 14:30, 9 June 2016

GStreamer is a modular node based player as well as encoder in a single application. It is possible to create chains of so called elements with a wide range of different plugins.

GStreamer

GStreamer is a library for constructing graphs of media-handling components. The applications it supports range from simple Ogg/Vorbis playback, audio/video streaming to complex audio (mixing) and video (non-linear editing) processing.

Applications can take advantage of advances in codec and filter technology transparently. Developers can add new codecs and filters by writing a simple plugin with a clean, generic interface.

Installing GStreamer

NicoLargo made a script to automatically install all the required packages for GStreamer on Ubuntu 10.04. Very simple and useful, just download and execute the script: http://svn.nicolargo.com/ubuntupostinstall/trunk/gstreamerinstall.sh

Tips

How to get 25 FPS ?

You won't get 25 fps if autoexposure is on and local brightness not high enough: the camera will automatically lower framerate for keeping clear picture. Either lighten up, or play with image settings (notably, gain).

Commandline examples

(Note: replace width and height accordingly to your camera setup and your computer's horsepower :p).

Displaying

careful with streams at higher resolution than 1920x1088

Display the cameras live video stream at its native resolution:

gst-launch-0.10 rtspsrc location=rtsp://192.168.0.9:554 ! rtpjpegdepay ! jpegdec ! queue ! ffmpegcolorspace ! xvimagesink sync=false

Display the cameras live video stream, resize to fit window (the ! videoscale element takes care of that)

gst-launch-0.10 rtspsrc location=rtsp://192.168.0.9:554 ! rtpjpegdepay ! jpegdec ! queue ! ffmpegcolorspace ! videoscale ! xvimagesink sync=false

Dumping

mjpeg dumping

gst-launch -v rtspsrc location=rtsp://192.168.0.9:554 ! queue ! rtpjpegdepay ! videorate ! capsfilter caps = "image/jpeg, framerate=(fraction)25/1, width=1024, height=768" ! queue ! matroskamux ! filesink location=/tmp/test.mkv

YUV Dumping

gst-launch -v rtspsrc location=rtsp://192.168.0.9:554 ! queue ! rtpjpegdepay ! queue ! jpegdec ! queue ! videorate ! capsfilter caps="video/x-raw-yuv, format=(fourcc)I420, width=(int)1024, height=(int)768, framerate=(fraction)25/1" ! queue ! avimux ! filesink location=/tmp/test.avi

Dump transcoding example

gst-launch filesrc location=test.mkv ! matroskademux ! queue ! jpegdec ! queue ! theoraenc bitrate=4000 ! queue ! oggmux ! filesink location=test.ogg

Live encoding

gst-launch -v rtspsrc location=rtsp://192.168.0.9:554 ! queue ! rtpjpegdepay ! queue ! jpegdec ! queue ! videorate ! capsfilter caps="video/x-raw-yuv, format=(fourcc)I420, width=(int)1024, height=(int)768, framerate=(fraction)25/1" ! queue ! theoraenc bitrate=4000 ! queue ! oggmux ! filesink location=/tmp/test1024.ogg

I did some benchmarks; a Core 2 Quad Q6600 (2.4 Ghz) is not powerful enough for h264 encoding @fullHD resolution (using 4 treads).