videobox: Much slower than videocrop

Submitted by Stirling Westrup

Link to original bug (#734679)

Description

I have an application that needs to do both video cropping and padding and which works with 4K videos. We chose videobox for the task because its the only element that does reasonable padding and the fact that it can also crop was a major bonus.

However, in time trials we've found that videobox is much, MUCH slower than videocrop, even when its just cropping. For example, using gstreamer 1.4.0, this pipeline runs on a stock ivy-bridge server driving a SMSC zero client display at about 45 fps:

gst-launch-1.0 -v filesrc location=Sintel-4K.mkv ! decodebin ! videoconvert ! videocrop left=100 ! videoscale ! fpsdisplaysink sync=false video-sink="xvimagesink display=:2"

The same pipeline, with videobox used instead of videocrop gives us an average of about 20 fps, which is a huge drop. Worse the video in question is 24 fps, so with videobox we cannot play realtime without dropping frames.