[Bug 725418] New: videoscale ignores add-borders property - Always maintains aspect ratio.

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=725418
  GStreamer | gst-plugins-base | git

           Summary: videoscale ignores add-borders property - Always
                    maintains aspect ratio.
    Classification: Platform
           Product: GStreamer
           Version: git
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-base
        AssignedTo: gstreamer-bugs at lists.freedesktop.org
        ReportedBy: swestrup at gmail.com
         QAContact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---


I have a simple need to take a calibration video and resize it to fill a
monitor screen, regardless of changes to aspect ratio.

The only extant element that performs video resizing is videoscale, and there
appears no way to make it modify the aspect-ratio of its incoming video.

Logically, the add-borders property should control this, as the only time one
would ever need to add borders as part of a rescaling is so as to maintain the
aspect ratio of input content while conforming to the aspect ratio of the
outgoing video frame.

In practice I have not been able to find any behavioral differences in
videoscale between when add-borders is operational and when it is not. In fact,
I've never even managed to get it to provide a visible border...

Here are two example pipelines only differing in the add-border property of
videoscale, and what I think they should display:

gst-launch-1.0 videotestsrc ! "video/x-raw, width=1920, height=1080" !
videocrop right=960 ! videoscale add-borders=true method=0 !
"video/x-raw,width=1920,height=1080" ! videoconvert ! xvimagesink display=:2

The pipeline above using the (default) true setting for add-borders takes a
test video, crops it to half width, and then asks it to be resized to full
width.

I would expect the result to be the left half of my test video, centered with
black borders on the right and left so as to once again be full width. In fact
what is produced appears to be the left half of my video with the right half
replaced (I assume) with a transparent alpha border.

When we use this pipeline:

gst-launch-1.0 videotestsrc ! "video/x-raw, width=1920, height=1080" !
videocrop right=960 ! videoscale add-borders=false method=0 !
"video/x-raw,width=1920,height=1080" ! videoconvert ! xvimagesink display=:2

The results are identical to the first pipeline, while what I expected to see
was the left half of my test video stretched horizontally to fill the entire
output frame. 

So, in summary, neither setting for add-borders appears to do what it should,
nor, in fact, does it appear to do anything at all.

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