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Re: [pulseaudio-discuss] Vulnerability in Webkit-GTK and PulseAudio volume handling


From: "Alexander E. Patrakov" <patrakov () gmail com>
Date: Fri, 11 Oct 2013 12:19:13 +0600

Colin Guthrie wrote:
What would be more interesting to me would be how the same code works on Windows 7 which I believe also implements a flat volume scheme (not sure about Win 8) and how it handles stream volumes in this context (background: http://www.patrickbaudisch.com/publications/2004-Baudisch-CHI04-FlatVolumeControl.pdf)

Here is a Windows 7 screenshot relevant to the flat volume idea. You need it to understand the text below.

http://permalink.gmane.org/gmane.comp.audio.pulseaudio.general/17426

Basically, Windows' flat volumes a just an UI feature of the default mixer application. Volume sliders inside applications still show relative-to-the-master volumes, as can be seen with Windows media player on that screenshot. In other words, Microsoft did not go as far as the referenced paper suggests.

As far as testing the bad javascript under Windows, I have asked my colleague to do just that in all major browsers (Chrome, Firefox, IE (with a different media file), non-webkit Opera, webkit Opera). Result: no bug. Javascript volume does not correspond to anything in the mixer application. The volume slider inside the browser jumps between 99% and 100%, but the volume slider in the mixer application can be set to any value, stays there, and the browser obeys. So the inside-the-browser volume control is just an additional element in the path, exposed to the user only inside the browser.

--
Alexander E. Patrakov


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