[gstreamer-bugs] [Bug 403597] New: Add ReplayGain reference level tag

[GStreamer (bugzilla.gnome.org)]

Do not reply to this via email (we are currently unable to handle email
responses and they get discarded).  You can add comments to this bug at
http://bugzilla.gnome.org/show_bug.cgi?id=403597

  GStreamer | gstreamer (core) | Ver: HEAD CVS

           Summary: Add ReplayGain reference level tag
           Product: GStreamer
           Version: HEAD CVS
          Platform: Other
        OS/Version: All
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: Normal
         Component: gstreamer (core)
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: mail at renestadler.de
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


With the new FLAC, a new tag was invented to store the ReplayGain reference
level.  It maps to the vorbis comment field name
"REPLAYGAIN_REFERENCE_LOUDNESS".  I propose adding support for this tag
alongside the other ReplayGain tags.  The purpose of the tag is to put an end
to the ambiguity that is inherent to the relative gain adjustment values.  So
in a sense, the invention of this tag comes 6 years too late, but hey!

I'm attaching a patch to add the tag as GST_TAG_REFERENCE_LEVEL.  I oppose
taking over the "reference loudness" term used for the comment field name
because doing so makes no sense; the ReplayGain proposed standard always uses
the term "reference level" to refer to the 89 dB (back then 83 dB) target
output level of the reference waveform.  The term "reference loudness" is only
used once (in the MATLAB script), where it refers to the result of the RG
function (which is meaningless by itself).

Another patch against gst-plugins-base will be attached that adds the new tag
to gstvorbistag.c, which should enable support in all formats that use vorbis
comments.

As part of another bug, I'll add support for the tag to the element(s) that are
part of the replaygain plugin.


-- 
Configure bugmail: http://bugzilla.gnome.org/userprefs.cgi?tab=email