User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0 Build ID: 20140825202822 Steps to reproduce: Two of the extensions I use (AlertBox, Download Status Bar) utilize HTML5 audio to play sounds. When my monitor is in power-saving mode (in Windows 7, see Control Panel > Power Options > Choose when to turn off the display) and a sound is played, the monitor turns back on. Sample code: var player = document.createElementNS("http://www.w3.org/1999/xhtml", "audio"); player.setAttribute("src", "mysound.wav"); player.play(); Actual results: Monitor turns on. Expected results: Monitor should remain off.

Could you attach a simple testcase (maybe a page/add-on running a clock to cast a sound after 1 min which is the default duration to dim or turn off the display), please?

Thank you for the testcase! I can reproduce this on Win8.1.

The tescase breaks screen dimming too (it's simpler to test). Reg range: good=2014-02-06 bad=2014-02-07 http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=1e9f169c9715&tochange=dedf12c4e805 Suspected bug: Chris Pearce — Bug 968603 - Add screen WakeLockListener on Win32 to disable screensaver. r=jimm

Only disable screen saver on the "screen" topic, instead of on all topics. This means that we'll only lock when playing in an HTMLVideoElement, which takes a "screen" lock when its play() function is called, and not when an HTMLAudioElement is played(). We'll ignore the "cpu" topic that HTMLMediaElement takes, and once bug 1022669 lands we'll not lock the "screen" topic in HTMLVideoElements that don't have a video stream (for audio elements loaded in an nsVideoDocument).

Any chance we could push this up to mozilla33?