[gentoo-user] [OT} GStreamer: How to view AND record a stream coming from an USB Webcam

[meino.cramer@gmx.de]

Hi,

After unsuccessfully trying vlc with a Logitech C920 HD Pro Webcam 
(over 2 seconds delay between audio and video). I played around
with gstreamer and from bits and pieces from the web I build
this line:

    gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-h264,width=1920,height=1080,framerate=30/1 ! \
    h264parse ! muxout. alsasrc device="hw:3,0" ! queue ! audioconvert ! lamemp3enc ! \ 
    muxout. matroskamux name=muxout streamable=true ! filesink location=c920.mp4

which records a Full HD video with audio to my harddisc. The delay is
minimal and the sync between audio and video is good.

But there is one disadvantage:
I cannot see what I am recording and I cannot watch the webcams stream
before I fire up the script because otherwise the device would be "already
in use" (I dont like scripts, which simply kill other applications when
called).

Any ideas or hints how to manage that?

Thank you very much in advance for any help!
Best regards,
mcc