[gst-devel] Need to confirm what constitutes an MJPEG stream

Wesley J. Miller WMiller at l6holdings.com
Wed Mar 31 23:10:09 CEST 2010

Hi All,

I am looking to do some work with an Axis camera that supplies me an MJPEG stream. I am new to gstreamer so I need some startup help understanding what's going on. 

I am using souphttpsrc as my source element.  The detected mime type from the camera after souphttpsrc is multipart/x-mixed-replace as expected.  

	gst-launch-0.10.exe -e souphttpsrc location="...?camera=2,  \
		width=320,height=240,framerate=(fraction)1/25" \
 		do-timestamp=true is_live=true 

If I now send this stream to a file, is it stored as MJPEG?  

	gst-launch-0.10.exe -e souphttpsrc location=... ! filesink location=soup.mjpg

FWIW, I tried a tool called JPLAYER from the net, a supposed mjpeg player.  It will play the "live" stream from http://10.xx.yy.zz but it won't play file:///.../soup.mjpg.  

Is MJPG a correct file type? (just in case jplayer is dumb enough to check the file extension and not the mime-type.)  The divx player can't play the file either.

However, the stored file will "play" using the same stream I use to see the live video feed. 

	gst-launch-0.10.exe -e souphttpsrc location=... ! multipartdemux \
		! jpegdec ! ffmpegcolorspace ! autovideosink

	// (swap filesrc for souphttpsrc)

	gst-launch-0.10.exe -e filesrc location=A.mjpg ! multipartdemux \
		! jpegdec ! ffmpegcolorspace ! autovideosink

Piping from souphttpsrc into multipartdemux yields a mime-type of image/jpeg.  This is the type of each demuxed frame, right? 

If I choose to store the output of the demuxer, does it remain a motion stream?  What type of file and/or stream is it?  Is there a preferred file extension for it?

If I attempt to play back the post-demuxer file, time elapses and the pipe terminates ok, but there is no output video shown.

	gst-launch-0.10.exe -e filesrc location=post-demux.jpg \
		! jpegdec ! ffmpegcolorspace ! autovideosink

Thanks for the any help.  


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