1021711 - There is no sound when HTML video is played at 0.25x rate

Status: RESOLVED WONTFIX

(Toolkit :: Video/Audio Controls, defect)

Description

[Mihaela Velimiroviciu (:mihaelav)]

Mozilla/5.0 (X11; Linux i686; rv:30.0) Gecko/20100101 Firefox/30.0 RC build 2

There is no sound in the HTML5 videos when played at 0.25 rate.

Steps to reproduce:
1. Go to https://www.youtube.com/html5 and enable HTML5 mode
2. Open a video which plays in HTML5 mode (e.g. https://www.youtube.com/watch?v=kkGeOWYOFoA)
3. Set the video speed to 0.25

Expected result:
Video and audio plays at the selected rate

Actual result:
Video plays at 0.25 speed, but there is no audio

Notes:
1. It is not a regression: the issue reproduces ever since the speed option was introduced (20.0)
2. Reproducible also on Aurora and Nightly
3. Sound doesn't start to play if the volume is changed (or mute/unmute) like in bug 887228

Comment 1

[Jared Wein [:jaws] (please needinfo? me)]

This was an intentional decision that was made when playbackRate was implemented. Rates lower than .5x and higher than 2x will have the audio automatically muted. The spec for playbackRate specifies this behavior:

"When the direction of playback is backwards, any corresponding audio must be muted. When the effective playback rate is so low or so high that the user agent cannot play audio usefully, the corresponding audio must also be muted. If the effective playback rate is not 1.0, the user agent may apply pitch adjustments to the audio as necessary to render it faithfully."

http://www.w3.org/TR/html5/embedded-content-0.html#effective-playback-rate