GStreamer saving video capture to file: intermittent freezes

[marc3 at rechte.fr]

Hello,

Capturing a video from a Web cam and displaying it in a Window is 
working perfectly. This is the command used:

$ gst-launch-1.0 -v -e uvch264src device=/dev/video0 name=src 
auto-start=true src.vidsrc ! 
video/x-h264,width=1280,height=720,framerate=30/1 ! h264parse ! 
avdec_h264 ! xvimagesink sync=false

When I save it to a file using the next command, the image freezes 
slightly every 2-3 seconds.

$ gst-launch-1.0 -e v4l2src device=/dev/video0 ! 
video/x-h264,width=1280,height=720,framerate=30/1 ! h264parse ! mp4mux ! 
filesink location=capture.mp4

A sample of the problem is located here: https://youtu.be/UOMq-Q7VwfA

I would appreciate your help !

Marc

$ rpm -q gstreamer1
gstreamer1-1.4.5-1.fc21.x86_64
gstreamer1-1.4.5-1.fc21.i686