[gstreamer-bugs] [Bug 604501] New: Equalizer results in almost complete loss of vocals

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=604501
  GStreamer | don't know | unspecified

           Summary: Equalizer results in almost complete loss of vocals
    Classification: Desktop
           Product: GStreamer
           Version: unspecified
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: major
          Priority: Normal
         Component: don't know
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: jenningsthecat at yahoo.ca
         QAContact: gstreamer-bugs at lists.sourceforge.net
      GNOME target: ---
     GNOME version: ---


I am using Decibel Audio Player 1.02, on Ubuntu 9.04. (I don't know what
gstreamer version DAP uses). I first filed this bug with Decibel Audio Player
on Launchpad, and was directed to file it here instead. Because I am using
gstreamer with Decibel Audio Player, the behaviour and replication descriptions
are necessarily DAP-specific.

The following behaviour applies both to regular mode, and to gapless mode using
the "--playbin2" switch. Also, it applies to both FLAC files and MP3 files.

When all of the equalizer sliders are set to the -24 dB position, any vocals or
other sounds that are in the centre of the soundstage, (i.e. sounds that are
equal in amplitude and phase in both stereo channels), are virtually lost. The
effect is very much like what is heard when listening to the 'difference'
signal that can be heard by, for example, connecting a speaker between the '+'
output of one channel and the '+' output of the other channel of most stereo
amplifiers. (I suspect that a flaw in the Equalizer algorithm is in fact
somehow causing it to extract the difference between the two channels).

To replicate, open the equalizer and click the Center button to 'zero' all of
the sliders. Play a song with strong 'phantom centre' information, (most stereo
recordings with vocals fall into this category), and note that the vocal is
centred between the two speakers. Then, adjust all of the equalizer sliders to
the very bottom, and note that the vocal is almost not present, (the degree of
this disappearance will vary from song to song), and also note that the music
has a 'spacey' quality. Click on the 'Center' button to restore normal
playback.

In a correctly functioning equalizer, moving all the sliders to the bottom
should result in considerably reduced volume, but the character, imaging, and
tonal balance of the music should remain substantially unchanged.

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