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[[Category:Linux_Operating_System]]
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== Overview ==
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[[Category:Visual]]
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This article will explain how to stream camera content over network thanks to [[GStreamer overview|GStreamer]] application on top of [[V4L2_camera_overview|V4L2 Linux<sup>&reg;</sup> kernel framework]].
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[[Category:GStreamer]]
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Capturing compressed JPEG pictures is an efficient way to send camera images to any local or remote player; JPEG pictures require a limited bandwidth while being fully interoperable.
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Find below some examples of command lines allowing to capture a continuous JPEG stream while playing it using various multimedia players, either local or remote.
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== Local streaming ==
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Here is an example of a local preview involving [[V4l2-ctl]] for JPEG pictures capture and [[Gst-play|gst-play]] GStreamer player for JPEG decoding and display. JPEG pictures are sent over a standard Linux pipe.
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{{Board$}} v4l2-ctl --set-parm=30;v4l2-ctl --set-fmt-video=width=640,height=480,pixelformat=JPEG --stream-mmap --stream-count=-1 {{highlight|'''--stream-to{{=}}-'''}} {{HighlightParam|2>/dev/null}} {{highlight|'''<nowiki>|</nowiki>'''}} gst-play-1.0 {{highlight|'''"fd://0"'''}}
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{{highlight|'''--stream-to{{=}}-'''}} tells [[V4l2-ctl]] to output binary captured content to standard output, which is then sent to pipe {{highlight|'''<nowiki>|</nowiki>'''}}.
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Special URI {{highlight|'''fd://0'''}} tells [[Gst-play|gst-play]] GStreamer player to read data from the pipe.
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Note the {{HighlightParam|2>/dev/null}} right after the [[V4l2-ctl]] command to remove the logs from console output.
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<br>
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<br>
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== UDP streaming ==
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{{Info|An internet connection is required, for example by plugging an ethernet cable on the [[STM32MP157C-EV1 - hardware description#MB1262-CN3|STM32MP157C-EV1 Evaluation board CN3 ethernet connector]]}}{{UpdateNeededForNewBoard|Point to the ethernet connector (if any) of the new board}}
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Get first the IP address {{highlight|'''aa.bb.cc.dd'''}} of the host PC using [[Ifconfig|ifconfig]] command:
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{{PC$}} ifconfig | grep "inet addr"
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    inet addr:{{highlight|'''aa.bb.cc.dd'''}}  Bcast:10.201.23.255  Mask:255.255.252.0
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    inet addr:127.0.0.1  Mask:255.0.0.0
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Then fill the {{HighlightParam|'''host{{=}}'''}} udpsink property with this IP address on the remote side:
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{{Board$}} v4l2-ctl --set-parm=30;v4l2-ctl --set-fmt-video=width=640,height=480,pixelformat=JPEG --stream-mmap --stream-count=-1 --stream-to=- 2>/dev/null | gst-launch-1.0 fdsrc ! jpegparse ! rtpjpegpay ! udpsink {{HighlightParam|'''host{{=}}'''}}{{highlight|'''aa.bb.cc.dd'''}} port=5000
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Then play the UDP stream on host PC:
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{{PC$}} gst-launch-1.0 udpsrc port=5000 ! application/x-rtp, encoding-name=JPEG ! rtpjpegdepay ! jpegparse ! decodebin ! autovideosink
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A new window will popup on host PC displaying the camera content.
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{{Info|Due to SDP protocol signaling, this solution is not fully interoperable because it needs a dedicated GStreamer command line to be played on host side}}
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<!--
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== RTSP streaming ==
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{{Warning| neet to explain gst-rtsp-server-launch-1.0 (derived from GStreamer example test_launch.c of rtsp libraries) and not yet documented}}
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Prerequesite:
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* Board connected to local network
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* RTSP server [[GStreamer overview|GStreamer]] libraries (libgstrtspserver-1.0.so* to be put in /usr/lib/gstreamer-1.0/)
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* gst-rtsp-server-launch-1.0 [[GStreamer overview|GStreamer]] utility
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* Get the ip address of the board:
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{{Board$}} ifconfig
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eth0      Link encap:Ethernet  HWaddr 00:80:E1:42:42:D8 
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          inet addr:{{blue|'''10.48.1.122'''}}  Bcast:10.48.3.255  Mask:255.255.252.0
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Capture VGA jpeg pictures and stream them over network using RTSP streaming protocol:
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{{Board$}} gst-rtsp-server-launch-1.0 {{blue|'''10.48.1.122'''}} 8081 "/test" "( v4l2src do-timestamp=true device=/dev/video0  ! image/jpeg, width=640, height=480, framerate=(fraction)15/1 ! queue ! jpegparse ! rtpjpegpay name=pay0 pt=96 )"
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stream ready at {{green|'''rtsp://10.48.1.122:8081/test'''}}
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Stream can then be played on host PC using any media player which support RTSP streaming such as [[GStreamer overview|GStreamer]] or VLC:
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{{PC$}} gst-play-1.0 {{green|'''rtsp://10.48.1.122:8081/test'''}}
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{{PC$}} cvlc {{green|'''rtsp://10.48.1.122:8081/test'''}}
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Stream can also be played on another target with same [[Gst-play|gst-play]] [[GStreamer overview|GStreamer]] utility:
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{{Board$}} gst-play-1.0 {{green|'''rtsp://10.48.1.122:8081/test'''}}
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-->
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<noinclude>
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{{ArticleBasedOnModel | How to article model}}
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{{PublicationRequestId | 7962 | 2018-07-05 | AlainF}}
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[[Category:How to run use cases]]
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[[Category:V4L2]]
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[[Category:GStreamer]]
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</noinclude>

2020年5月8日 (五) 22:52的最新版本

Overview

This article will explain how to stream camera content over network thanks to GStreamer application on top of V4L2 Linux® kernel framework.

Capturing compressed JPEG pictures is an efficient way to send camera images to any local or remote player; JPEG pictures require a limited bandwidth while being fully interoperable.

Find below some examples of command lines allowing to capture a continuous JPEG stream while playing it using various multimedia players, either local or remote.

Local streaming

Here is an example of a local preview involving V4l2-ctl for JPEG pictures capture and gst-play GStreamer player for JPEG decoding and display. JPEG pictures are sent over a standard Linux pipe. 

Board $> v4l2-ctl --set-parm=30;v4l2-ctl --set-fmt-video=width=640,height=480,pixelformat=JPEG --stream-mmap --stream-count=-1 --stream-to=- 2>/dev/null | gst-play-1.0 "fd://0"

--stream-to=- tells V4l2-ctl to output binary captured content to standard output, which is then sent to pipe |.

Special URI fd://0 tells gst-play GStreamer player to read data from the pipe.

Note the 2>/dev/null right after the V4l2-ctl command to remove the logs from console output.

UDP streaming

Info.png An internet connection is required, for example by plugging an ethernet cable on the STM32MP157C-EV1 Evaluation board CN3 ethernet connector

Get first the IP address aa.bb.cc.dd of the host PC using ifconfig command: 

PC $> ifconfig | grep "inet addr"
   inet addr:aa.bb.cc.dd  Bcast:10.201.23.255  Mask:255.255.252.0
   inet addr:127.0.0.1  Mask:255.0.0.0

Then fill the host= udpsink property with this IP address on the remote side: 

Board $> v4l2-ctl --set-parm=30;v4l2-ctl --set-fmt-video=width=640,height=480,pixelformat=JPEG --stream-mmap --stream-count=-1 --stream-to=- 2>/dev/null | gst-launch-1.0 fdsrc ! jpegparse ! rtpjpegpay ! udpsink host=aa.bb.cc.dd port=5000

Then play the UDP stream on host PC: 

PC $> gst-launch-1.0 udpsrc port=5000 ! application/x-rtp, encoding-name=JPEG ! rtpjpegdepay ! jpegparse ! decodebin ! autovideosink

A new window will popup on host PC displaying the camera content.

Info.png Due to SDP protocol signaling, this solution is not fully interoperable because it needs a dedicated GStreamer command line to be played on host side



<securetransclude src="ProtectedTemplate:ArticleBasedOnModel" params="How to article model"></securetransclude> <securetransclude src="ProtectedTemplate:PublicationRequestId" params="7962 | 2018-07-05 | AlainF"></securetransclude>

取自“http://wiki.100ask.org/index.php?title=How_to_stream_camera_over_network&oldid=6862”