Using gstreamer
Contents
Gstreamer and live video processing over the network
Gstreamer is very suited to live video and audio processing, notably for live decoding/encoding, audio muxing.
Requirements
You will need
- a fairly recent gstreamer distribution, with the rtpjpegdepay plugin
- a relatively powerful computer to decode real time
Limitations
You will not (at this time) be able to decode the elphel 353 cameras on resolutions > 1920x1080 (which is the highest resolution you can reach with 25 fps anyway), because of the RTP payloading limits, with 25 fps anyway.
If you don't, you'll just have to build it yourself (see this guide from PiTiVi).
Tips
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).
Command line experiments
(Note: replace width and height accordingly to your camera setup and your computer's horsepower :p).
Displaying
gst-launch -v rtspsrc location=rtsp://elphel:554 ! queue ! rtpjpegdepay ! queue ! jpegdec ! queue ! xvimagesink sync=false
Dumping
mjpeg dumping
gst-launch -v rtspsrc location=rtsp://elphel: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://elphel: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://elphel: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
