Can't save to a file and display at the same time

[xj25vm]

I'm trying to capture video from a webcam in mjpeg, display it on the monitor (on the same pc) and transcode it to mpeg1 and save it to a file at the same time.

I can successfully transcode it and save it using the following command:

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cvlc --no-audio v4l2:///dev/video0:width=640:height=480:chroma=mjpg:fps=25 --sout "#transcode{vcodec=mp1v,vb=1024,width=640,height=480}:standard{access=file,mux=mpeg1,dst='my_test_file.mpg'}"

But when I try to save to file and display at the same time using the following command:

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cvlc --no-audio v4l2:///dev/video0:width=640:height=480:chroma=mjpg:fps=25 --sout "#duplicate{dst=display, dst={transcode{vcodec=mp1v,vb=1024,width=640,height=480}:standard{access=file,mux=mpeg1,dst='my_test_file.mpg'}}"

... the video shows on the screen, but the saved .mpg file is 4 bytes and, obviously, contains nothing. With -vvv the console scrolls on and on the following

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stream_out_transcode stream out debug: late picture skipped avcodec decoder warning: cannot decode one frame

Does anybody know what is going on?

I'm using VLC 1.1.3 on Slackware 13.1