Gstreamer save camera video input to file returns empty file

Question

I'm trying to save the video input (it can also be frame by frame) from a camera, whose input I can display like this:

gst-launch-1.0 udpsrc port=50004 ! application/x-rtp,encoding=JPEG,payload=26 ! rtpjpegdepay ! decodebin ! videoconvert ! autovideosink

I want to save this video to a file, either in video format or frame by frame. So I try to run

gst-launch-1.0 udpsrc port=50004 ! application/x-rtp,encoding=JPEG,payload=26 ! rtpjpegdepay ! decodebin ! videoconvert ! avimux ! filesink location=video.avi

But my video.avi file is empty. What am I doing wrong? I am a beginner in GStreamer and I can't find useful information online so I can't figure out what each part of that pipeline is doing.

EDIT

Running with verbose I get this:

Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
/GstPipeline:pipeline0/GstCapsFilter:capsfilter0.GstPad:src: caps = application/x-rtp, encoding=(string)JPEG, payload=(int)26, media=(string)video, clock-rate=(int)90000
/GstPipeline:pipeline0/GstRtpJPEGDepay:rtpjpegdepay0.GstPad:sink: caps = application/x-rtp, encoding=(string)JPEG, payload=(int)26, media=(string)video, clock-rate=(int)90000
/GstPipeline:pipeline0/GstRtpJPEGDepay:rtpjpegdepay0.GstPad:src: caps = image/jpeg, framerate=(fraction)0/1, width=(int)640, height=(int)480
/GstPipeline:pipeline0/GstDecodeBin:decodebin0.GstGhostPad:sink.GstProxyPad:proxypad0: caps = image/jpeg, framerate=(fraction)0/1, width=(int)640, height=(int)480
/GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstTypeFindElement:typefind.GstPad:src: caps = image/jpeg, framerate=(fraction)0/1, width=(int)640, height=(int)480
[INFO]  bitstreamMode 1, chromaInterleave 0, mapType 0, tiled2LinearEnable 0
/GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstImxVpuDecoder:imxvpudecoder0.GstPad:sink: caps = image/jpeg, framerate=(fraction)0/1, width=(int)640, height=(int)480
/GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstTypeFindElement:typefind.GstPad:sink: caps = image/jpeg, framerate=(fraction)0/1, width=(int)640, height=(int)480
/GstPipeline:pipeline0/GstDecodeBin:decodebin0.GstGhostPad:sink: caps = image/jpeg, framerate=(fraction)0/1, width=(int)640, height=(int)480
/GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstImxVpuDecoder:imxvpudecoder0.GstPad:src: caps = video/x-raw, format=(string)I420, width=(int)640, height=(int)480, interlace-mode=(string)progressive, pixel-aspect-ratio=(fraction)1/1, chroma-site=(string)jpeg, colorimetry=(string)bt601, framerate=(fraction)0/1
/GstPipeline:pipeline0/GstVideoConvert:videoconvert0.GstPad:src: caps = video/x-raw, format=(string)I420, width=(int)640, height=(int)480, interlace-mode=(string)progressive, pixel-aspect-ratio=(fraction)1/1, chroma-site=(string)jpeg, colorimetry=(string)bt601, framerate=(fraction)0/1
/GstPipeline:pipeline0/GstVideoConvert:videoconvert0.GstPad:sink: caps = video/x-raw, format=(string)I420, width=(int)640, height=(int)480, interlace-mode=(string)progressive, pixel-aspect-ratio=(fraction)1/1, chroma-site=(string)jpeg, colorimetry=(string)bt601, framerate=(fraction)0/1
/GstPipeline:pipeline0/GstDecodeBin:decodebin0.GstDecodePad:src_0.GstProxyPad:proxypad1: caps = video/x-raw, format=(string)I420, width=(int)640, height=(int)480, interlace-mode=(string)progressive, pixel-aspect-ratio=(fraction)1/1, chroma-site=(string)jpeg, colorimetry=(string)bt601, framerate=(fraction)0/1

Answer 1

I could eventually write the stream of images using the following command:

gst-launch-1.0 udpsrc port=50004 ! application/x-rtp,encoding=JPEG,payload=26 ! rtpjpegdepay ! matroskamux ! filesink location=video.mkv

Answer 2

"encoding=JPEG" just specifies jpeg at that stage of the pipeline, but that is decoded by decodebin later, resulting in uncompressed, raw video.

You can check what encoders your gstreamer install supports with

gst-inspect-1.0 | grep enc

This also lists audio encoders. Probably you have to install additional gstreamer packages to get any or more encoders, like gstreamer1.0-plugins-bad or gstreamer1.0-plugins-ugly (this package contains x264enc).

Then try the pipeline from @Alper again:

gst-launch-1.0 udpsrc port=50004 ! application/x-rtp,encoding=JPEG,payload=26 ! rtpjpegdepay \
! decodebin ! videoconvert ! x264enc ! avimux ! filesink location=video.avi