1515054 - Improve the preserve-pitch algorithm in audio playback

Status: RESOLVED DUPLICATE of bug 1427267

(Core :: Audio/Video: Playback, defect, P3)

Description

[Aria Minaei]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:64.0) Gecko/20100101 Firefox/64.0

Steps to reproduce:

1. Navigate to any web page with a video/audio element that includes speech and play the video.
2. Open devtools.
3. Select the audio/video element.
4. Open console and type `$0.playbackRate = 1.75` (or any number higher than 1.25)

(Alternatively you can try opening a video on YouTube and choose a high playback rate from the video player's options menu)


Actual results:

The playback rate does go up, and the pitch of the sound gets preserved. However, the audio sounds robotic and unnatural. There are sudden changes in the pitch which make phonemes difficult to distinguish and words hard to understand. Still usable, but distracting, and generally not a good fit for watching lectures/conference videos on double speed.


Expected results:

For an example of how the pitch-preserving algorithm may be improved, try listening to the same audio/video on double speed on Chrome. I find the speeches noticeably more clear and easier to understand. This is one of the very few use cases for which I still use Chrome for one-off uses.

Comment 1

[Gyula Palko[:gpalko]]

I'm setting the component, in order to involve the development team to review this and decide, if the requested improvement will be implemented or not.

Comment 2

[Karl Tomlinson (:karlt)]

Confirmed with 64.0b14 on https://youtu.be/IdNHNZmVTxc?t=43 .
It is as if there is an echo or a similar sound at a lower pitch.
The same effect may be present with Google Chrome 71.0.3578.80 but it is much less noticeable.