[pulseaudio-tickets] [Bug 51230] New: GNOME alert sounds cause discontinuities in music, but only the first time per track.

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=51230

             Bug #: 51230
           Summary: GNOME alert sounds cause discontinuities in music, but
                    only the first time per track.
    Classification: Unclassified
           Product: PulseAudio
           Version: unspecified
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: misc
        AssignedTo: pulseaudio-bugs at lists.freedesktop.org
        ReportedBy: will.thompson at collabora.co.uk
         QAContact: pulseaudio-bugs at lists.freedesktop.org
                CC: lennart at poettering.net


When playing a track in Banshee or Totem, GNOME alert sounds (such as the
popping sound when changing volume, or the chime when hitting backspace in an
empty text field) cause a discontinuity in the music the first time one is
played during the track.

I experimented briefly with VLC and mplayer: the issue doesn't seem to occur
with these. So perhaps the issue lies with GStreamer rather than Pulse? Pulse
seems like a reasonable starting point anyway.

Steps to reproduce:

1. Open a piece of music (with a prominent beat, to make it easy to hear the
discontinuity) in Totem, and press play.
2. In an empty Gtk text field (the text entry in an Empathy conversation window
works fine), listen carefully and hit backspace to trigger an alert sound.
3. You should notice a very small chunk of the music is skipped when the alert
plays.
4. Now hit backspace again. No discontinuity this time.
5. Skip to another track in the player, and repeat. The first alert tone will
again cause a discontinuity.

Relevant Debian package versions:

gstreamer0.10-pulseaudio:amd64 0.10.31-3
libcanberra-pulse:amd64 0.28-4
libpulse0:amd64 2.0-3
pulseaudio 2.0-3
vlc 2.0.1-4+b2
vlc-plugin-pulse 2.0.1-4+b2
mplayer 2:1.0~rc4.dfsg1+svn34540-1+b2

My /etc/pulse/daemon.conf is unmodified from the distro-supplied (and, I
presume, upstream-supplied) default, where every line is commented out. Arun
suggested setting:

  deferred-volume-extra-delay-usec = 10000

To my ears, this made the discontinuity slightly more pronounced.

Arun said:

> so the problem is likely something broken with rewinds
> mixing in a new sound means rewinding buffers, rendering new, mixed output

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