Still can't get videomixer to do live video at full frame rate

wally_bkg wb666greene at
Wed Aug 17 06:48:13 PDT 2011

Videomixer2 was the first thing I tried, doesn't exist in the Ubuntu 10.04

gst-inspect videomixer2
No such element or plugin 'videomixer2'

I thought the documentation blurb said videomixer2 will replace videomixer,
I'd assumed that had happened by now.

gst-inspect videomixer
Factory Details:
  Long name:	Video mixer
  Class:	Filter/Editor/Video
  Description:	Mix multiple video streams
  Author(s):	Wim Taymans <wim at>
  Rank:		primary (256)

Plugin Details:
  Name:			videomixer
  Description:		Video mixer
  Filename:		/usr/lib/gstreamer-0.10/
  Version:		0.10.21
  License:		LGPL
  Source module:	gst-plugins-good
  Binary package:	GStreamer Good Plugins (Ubuntu)
  Origin URL:

Curious that adding timeoverlays appears to fix the performance problem (at
least for a while):
// live dual video
gst-launch v4l2src device=/dev/video0 ! \
video/x-raw-yuv,format =\(fourcc\)I420, framerate=\(fraction\)30000/1001,
width=640, height=480 ! timeoverlay ! \
videomixer name=mix sink_0::alpha=1.0 sink_0::xpos=0 sink_0::ypos=0
sink_1::alpha=1.0 sink_1::xpos=0 sink_1::ypos=480  sink_2::zorder=3 !
xvimagesink \
v4l2src device=/dev/video1 ! video/x-raw-yuv,format=\(fourcc\)I420,
framerate=\(fraction\)30000/1001, width=640, height=480 ! timeoverlay ! mix.
videotestsrc pattern=2 ! video/x-raw-yuv,format=\(fourcc\)I420,
framerate=\(fraction\)1/1, width=640, height=960 ! mix.

// third image for full speed reference, started in second xterm window:
gst-launch v4l2src device=/dev/video4 ! video/x-raw-yuv,format
=\(fourcc\)I420, framerate=\(fraction\)30000/1001, width=640, height=480 ! \
timeoverlay ! xvimagesink

Top now shows about 57% for the stacked dual image display, and 45% for the
third image gst-launch command, with Xorg at about 11%.

I dislike voodoo programming in the absence of decent documentation,  but
this seems to be usable, its been running the whole time I've been composing
this message -- spoke too soon now its clearly not maintaining the frame
rate as the incrementing of the time overlay clearly shows vs. the reference
frame.  There are other "bar-codes" overlaid on the video tape I playback
for testing that makes it easy to see if the frame rate is full or not. 
Normal epochs need to be a lot longer than this!

I'll try playing with the sync property on the xvimagesink and anything else
I can think of, but its about time to give up and go to "Plan B".

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