Ubuntu 14.04 Gstreamer自动视频接收器

Question

I am trying to get a Gstreamer video stream running on Ubuntu 14.04 but the receiver side is unable to display video properly. I have a sender pipeline sending MJPEG images which I start like this:

gst-launch-1.0 -v videotestsrc ! jpegenc ! rtpjpegpay ! udpsink host=127.0.0.1 port=5200

The output is:

Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
/GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0.GstPad:src: caps = video/x-raw, width=(int)320, height=(int)240, framerate=(fraction)30/1, format=(string)I420, pixel-aspect-ratio=(fraction)1/1, interlace-mode=(string)progressive
/GstPipeline:pipeline0/GstJpegEnc:jpegenc0.GstPad:sink: caps = video/x-raw, width=(int)320, height=(int)240, framerate=(fraction)30/1, format=(string)I420, pixel-aspect-ratio=(fraction)1/1, interlace-mode=(string)progressive
/GstPipeline:pipeline0/GstJpegEnc:jpegenc0.GstPad:src: caps = image/jpeg, sof-marker=(int)0, width=(int)320, height=(int)240, pixel-aspect-ratio=(fraction)1/1, framerate=(fraction)30/1
/GstPipeline:pipeline0/GstRtpJPEGPay:rtpjpegpay0.GstPad:src: caps = application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)JPEG, a-framerate=(string)30.000000, a-framesize=(string)320-240, payload=(int)96, ssrc=(uint)1970481773, timestamp-offset=(uint)1012832172, seqnum-offset=(uint)21614
/GstPipeline:pipeline0/GstUDPSink:udpsink0.GstPad:sink: caps = application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)JPEG, a-framerate=(string)30.000000, a-framesize=(string)320-240, payload=(int)96, ssrc=(uint)1970481773, timestamp-offset=(uint)1012832172, seqnum-offset=(uint)21614
/GstPipeline:pipeline0/GstRtpJPEGPay:rtpjpegpay0.GstPad:sink: caps = image/jpeg, sof-marker=(int)0, width=(int)320, height=(int)240, pixel-aspect-ratio=(fraction)1/1, framerate=(fraction)30/1
/GstPipeline:pipeline0/GstRtpJPEGPay:rtpjpegpay0: timestamp = 1012832172
/GstPipeline:pipeline0/GstRtpJPEGPay:rtpjpegpay0: seqnum = 21614
Pipeline is PREROLLED ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock

The receive pipeline is:

gst-launch-1.0 udpsrc port=5200 caps="application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)JPEG, a-framerate=(string)30.000000, a-framesize=(string)320-240, payload=(int)96" ! rtpjpegdepay ! jpegdec ! xvimagesink

Notice I have copied the caps from the sender info.

However, I keep getting a "could not send sticky events" error, and the receiver terminates immediately. What could I be doing wrong? My output is below:

Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
0:00:00.016961467 12229      0x266a400 WARN                GST_PADS gstpad.c:3669:gst_pad_peer_query:<jpegdec0:src> could not send sticky events
0:00:00.017297845 12229      0x266a400 WARN                 basesrc gstbasesrc.c:2865:gst_base_src_loop:<udpsrc0> error: Internal data flow error.
0:00:00.017306308 12229      0x266a400 WARN                 basesrc gstbasesrc.c:2865:gst_base_src_loop:<udpsrc0> error: streaming task paused, reason not-negotiated (-4)
ERROR: from element /GstPipeline:pipeline0/GstUDPSrc:udpsrc0: Internal data flow error.
Additional debug info:
gstbasesrc.c(2865): gst_base_src_loop (): /GstPipeline:pipeline0/GstUDPSrc:udpsrc0:
streaming task paused, reason not-negotiated (-4)
Execution ended after 0:00:00.000651039
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

I have tried the autovideosink, ximagesink, with the same results.

Thanks.

Answer 1

Okey you just need to add videoconvert - the jpegdec generates video which xvimagesink does not understand:

gst-launch-1.0 udpsrc port=5200 ! application/x-rtp\,\ media\=\(string\)video\,\ clock-rate\=\(int\)90000\,\ encoding-name\=\(string\)JPEG\,\ a-framerate\=\(string\)\"30\\\,000000\"\,\ payload\=\(int\)26\,\ ssrc\=\(uint\)2512101225\,\ timestamp-offset\=\(uint\)1627080146\,\ seqnum-offset\=\(uint\)4727 ! rtpjpegdepay ! jpegdec ! videoconvert ! xvimagesink

How I figured this out? by using fakesink this way:

udpsrc ! fakesink -v

worked,then

udpsrc ! rptjpegdepay ! fakesink 

worked again .. so I continued like this and find out that the problem is really in xvimagesink.. Its weird that we do not get more explicit error message..

Also you can debug the app with:

GST_DEBUG=4 gst-launch-1.0 udpsrc .....

You can scroll to the part where not negotiated happened and look around.