When using either the gstreamer or the vlc backend, any sound event is preceded by a short but powerful crackling. a/ This never occurs when using the xine backend b/ There is no initial crackling when listening a multimedia file with dragonplayer even with either the gstreamer or the vlc backend. c/ Using whatever x86_64 kernel from at least 2.6.38 to 3.2.1 included d/ Using KDE 4.7.4 but this was also the case under last 4.6 stable e/ Using media-libs/phonon-4.5.1-r1 + media-libs/phonon-gstreamer-4.5.0 + media-libs/phonon-vlc-0.4.0 + media-libs/phonon-xine-4.4.4 f/ No use of PulseAudio. The backend outputs to Alsa Default which is a pseudo device essentially made around dmix resampling_best to 44.100 g/ The audio device is an ICE1712 compatible device outputting through its analog outputs to an external audio amplifier. Reproducible: Always I justify the reporting of this bug as well as its severity by the fact phonon-xine was removed from portage's tree.
Please file a upstream bug.
I've been using phonon-vlc since we added it to the tree and even though I've felt some "distortion" and "time lag" effects in the early stages, it currently works very well. I don't recall ever having the type of problem you describe. I use phonon-vlc on a variety of boxes, including several desktops and laptops and output the sound to headphones, desktop speakers and through HDMI to my AV receiver.
After investigating a little more, I think the problem is the lack of resampling. Because : - KDE sound events are 48Khz but my device is set up to 44.1 Khz - If I play the file with any player without any specific resampling, I can hear the sound with the same crackling as the one reported when "played" through phonon-vlc | phonon-gstreamer. The problem could be in fact linked to https://bugs.gentoo.org/show_bug.cgi?id=402151 I just reported. Because as I implemented (and successfully tested with several players) resampling to 44.1 Khz as part of my Alsa_Default pseudo-device, if KDE sound events are not resampled when selecting the Alsa_Default device it would just mean that Alsa_Default is not the device actually used by phonon-vlc.
(In reply to comment #1) > Please file a upstream bug. We cant much do about it. So please file a bug upstream.
(In reply to comment #3) Since it is now possible to direct phonon-vlc's output to whatever resampling capable pseudo device, thanks to Bug 402151 resolution, this bug no longer concerns phonon-vlc. This would confirm that this crackling problem is actually a resampling problem. The bug remains with phonon-gstreamer in its 4.6.2-r1 version.
