[gstreamer-bugs] [Bug 619508] New: [tag] Add image orientation tag

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=619508
  GStreamer | gstreamer (core) | git

           Summary: [tag] Add image orientation tag
    Classification: Desktop
           Product: GStreamer
           Version: git
        OS/Version: All
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: Normal
         Component: gstreamer (core)
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: thiago.sousa.santos at collabora.co.uk
         QAContact: gstreamer-bugs at lists.sourceforge.net
      GNOME target: ---
     GNOME version: ---


This is the "Orientation" tag description from exif's spec:

Orientation 
The image orientation viewed in terms of rows and columns.  
Tag = 274 (112.H) 
Type = SHORT 
Count = 1 
Default = 1 
1 = The 0th row is at the visual top of the image, and the 0th column is the
visual left-hand side. 
2 = The 0th row is at the visual top of the image, and the 0th column is the
visual right-hand side. 
3 = The 0th row is at the visual bottom of the image, and the 0th column is the
visual right-hand side. 
4 = The 0th row is at the visual bottom of the image, and the 0th column is the
visual left-hand side. 
5 = The 0th row is the visual left-hand side of the image, and the 0th column
is the visual top. 
6 = The 0th row is the visual right-hand side of the image, and the 0th column
is the visual top. 
7 = The 0th row is the visual right-hand side of the image, and the 0th column
is the visual bottom. 
8 = The 0th row is the visual left-hand side of the image, and the 0th column
is the visual bottom. 
Other = reserved 


Shortly, it tells us how should we mirror or rotate the picture before
displaying it to users. I know some applications handle this properly (gimp and
windows image viewer, for example), we could make gstreamer handle it, too.

Adding a tag is trivial, I'm just asking here how should we represent this one
as we don't have enum tags so far.

One option is to use strings as 'mirror-vertical', 'rotate-90-cw'... The
strings have intuitive names, but I think this is error prone unless we have
macros for each one. But if we are going to use macros, I'd prefer them to
represent the integers from the spec.

Keep in mind that there are some other tags from exif that are enums as well,
so we might want to take a longer term and generic decision here.

-- 
Configure bugmail: https://bugzilla.gnome.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
You are the assignee for the bug.