1

So, I'm starting to play around with gstreamer and I'm able to do very simple pipes such as 

gst-launch-1.0 -v v4l2src device=/dev/video1 ! video/x-raw,format=YUY2,width=640,height=480,framerate=10/1 ! videoconvert ! autovideosink

Now, as my USB webcam (which is video1, video0 being the computer's built in camera) supports h264 (I have checked using lsusb), I would like to try to get the h264 feed directly. I understand that this feed is muxed in the mjpeg one, but looking around on the web it seems that gstreamer is able to get it nonetheless.

Since my end goal is to stream it from a Beaglebone, I made an attempt using the solution given to this post (adding a listener from a different terminal):

#sender
gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-264,width=320,height=90,framerate=10/1 ! tcpserversink host=192.168.148.112 port=9999

But this yields the following error : 

WARNING: erroneous pipeline: could not link v4l2src0 to tcpserversink0

I also tried something similar to my first command, changing the source from raw to h264 (based on that post , trying the full command given there gives the same error message)

gst-launch-1.0 -v v4l2src device=/dev/video1 ! video/x-h264,width=640,height=480,framerate=10/1 ! h264parse ! avdec_h264 ! autovideosink

But again, this did not work either:

Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Internal data flow error.
Additional debug info:
gstbasesrc.c(2948): gst_base_src_loop (): /GstPipeline:pipeline0/GstV4l2Src:v4l2src0:
streaming task paused, reason not-negotiated (-4)
Execution ended after 0:00:00.036309961
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

I admit this is driving me pretty crazy: looking on SO or elsewhere on the web, there seems to be a lot of people who made it work with exactly the same webcam as the one I have (Logitech C920), but I keep running into issues one after the other.

What would be an example of correct pipe to extract the h264 from that webcam?

Nicolas Couvrat
  • 371
  • 2
  • 13

1 Answers1

1

You definitely need to use a payloader before it hits the wire. For example rtph264pay. Here is an example that cannot test as I don't have your hardware available. I have working udp examples from alternates sources if this doesn't steer you in the right direction.

server

gst-launch v4l2src device=/dev/video1 \
! video/x-264,width=320,height=90,framerate=10/1 \
! x264enc \
! queue \
! rtph264pay, config-interval=3, pt=96, mtu=1500 \
! queue \
! tcpserversink host=127.0.0.1 port=9002

client

gst-launch tcpserversrc host=127.0.0.1 port=9002 \
! application/x-rtp, media=video, clock-rate=90000, encoding-name=H264, payload=96 \
! rtph264depay \
! video/x-h264 \
! queue \
! ffdec_h264 \
! queue \
! xvimagesink
Josiah DeWitt
  • 1,594
  • 13
  • 15