Bug 314789

Summary:	No sound when playing html5 video
Product:	[Unmaintained] kdelibs	Reporter:	LuRan <hephooey_dev>
Component:	kdewebkit	Assignee:	webkit-devel
Status:	RESOLVED NOT A BUG
Severity:	normal	CC:	adawit
Priority:	NOR
Version:	Git
Target Milestone:	---
Platform:	Compiled Sources
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description LuRan 2013-02-09 19:59:06 UTC

This is a very strange bug: At least since last friday, some change in either the kde (kdelibs is 4.10 branch, others are master) or qt (4.8 branch) or the qtwebkit (2.3 branch) git made the sound disappear when I watch html5 video in either kwebkitpart or rekonq. It does not seems to be a bug in Phonon since notification sound and amarok work fine. The sound is however fine when I use QtTestBrowser. I disabled the internal phonon comes with Qt and compiled phonon with vlc and gstream backend from the git. I am using pulseaudio and there is no new client/source show up in the pacmd output when playing html5 video. The files downloaded by kio seems fine, I can play them using mplayer. It seems something go wrong when passing the kio downloaded file to playing in qtwebkit.

Reproducible: Always

Steps to Reproduce:
1. Open any html youtube video, http://www.youtube.com/watch?v=00C_T7lWPbw&list=SP2D1942A4688E9D63 for example in rekonq or kwebkitpart
2.
3.
Actual Results:  
The video plays but no sound

Expected Results:  
Sound

Comment 1 Dawit Alemayehu 2013-02-09 20:51:57 UTC

QtWebKit no longer uses phonon as it multimedia backend. Instead it directly relies on webkit's builtin support for gstreamer. It has been that way for a while [1]. 

The only time I encounter the issue you describe here, no sound when playing HTML5 video, is when I switch KDE's Phonon backend to something other than Gstreamer, e.g. VLC. Otherwise,  I see and hear vide very well from HTML 5 videos such as this one on HTML 5 in QtWebKit [2]. So the question is what is your KDE Multimedia backend set to ? 

[1] https://lists.macosforge.org/pipermail/webkit-qt/2011-June/001633.html
[2] http://qt-project.org/videos/watch/html5-in-qtwebkit

Comment 2 LuRan 2013-02-09 21:20:20 UTC

I actually tried both gstreamer and vlc backend (and logout/login to make sure the change actually applied). Still no sound, I recently upgraded to gstreamer 1.0.5 and pulseaudio 2.1, maybe that is somehow related to this problem. Still it is strange that QtTestBrowser works fine while kwebkitpart does not. Is there anyway to get more output related to video play from webkit? Now all I can see in the output of rekonq is KIO infomation.

Comment 3 LuRan 2013-02-09 21:33:11 UTC

When I wrote the previous reply I have not try to watch Alexis Menard's video, this one is interesting, the video plays fine in rekonq (with sound!), but in konqueror with kwebkitpart I cannot play it at all. Also there seems to be no tmp file downloaded by rekonq to playing this video. But anyway the youtube videos have no sound at all.

Comment 4 Dawit Alemayehu 2013-02-09 22:31:44 UTC

(In reply to comment #3)
> When I wrote the previous reply I have not try to watch Alexis Menard's
> video, this one is interesting, the video plays fine in rekonq (with
> sound!), but in konqueror with kwebkitpart I cannot play it at all. Also
> there seems to be no tmp file downloaded by rekonq to playing this video.
> But anyway the youtube videos have no sound at all.

The video is going to be streamed and and stream is supposed to be played directly so there should not be any temporary file download. However, it still does not make sense how it works for some videos and not others in reKonq, does not work at all in Konqueror and works fine in QtTestBrowser. Are you running git versions of kwebkitpart too ? 

I personally can hear the sound in both videos just fine using kwebkitpart (master git) + Konqueror.

Comment 5 LuRan 2013-02-10 02:26:23 UTC

I was using the 1.3 branch when I reported the bug, but the master branch does not improve it, it seems the webkit code in kde do not have any suspicious changes in the last few month. I actually doubt this is a kwebkitpart bug from the beginning. Since in your system everything is fine I guess I should check other library and maybe some config files next. Let me leave this bug open for the moment, when I find a solution I will close the bug.

Comment 6 LuRan 2013-02-16 16:22:04 UTC

After downgrade gst-plugins-* to 0.10 the problem disappeared, appearently I am too stupid to notice QtTestBrowser is using flash when playing the youtube video, sorry about the noise.