[Bug 1654480] Re: HTML5 sound choppy when played at 4x

Thu Dec 27 11:14:42 UTC 2018

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On 2017-12-28T13:31:48+00:00 S-bugzilla-mozilla wrote:

Steps to reproduce:

0. (fresh profile)
1. Navigate to any page with a <video> element on it

- Preferably with human speech, since it's much more noticeable that way
- Suggested links: https://vimeo.com/64654583, https://www.youtube.com/watch?v=JWD1Fpdd4Pc, https://www.youtube.com/watch?v=OyfBQmvr2Hc

2. Open the JS Console
3. Run `document.querySelector('video').playbackRate = 3.5` (any number > 2 works, but higher speeds are much more noticeable)
4. Listen to the audio (there's nothing wrong with the video)

Expected results: Smooth audio playback with no audible stuttering,
skipping, or artifacts

Observed results: Audio with skipping and stuttering, especially
noticeable when there's human speech

Notes:

- Playback works just fine on WebKit and its derivatives (Opera, Chrome, Safari, Electron-based apps)
- Playback is also just fine on VLC
- Reproduced on: my 2014 MacBook Pro, a 2013 Mac Mini, and a 1st-gen MacBook, all running macOS High Sierra 10.13.2

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/2

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On 2018-01-03T09:15:41+00:00 Suro001 wrote:

I can't repro the issue.

I suspect you network connection is not fast enough so playback can
consume data without underflow. Can you try to download the file and
play it on the local storage? Thanks!

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/3

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On 2018-01-09T07:17:01+00:00 S-bugzilla-mozilla wrote:

Playing a video from the local filesystem has the same effect.
Networking is not the issue since video playback works perfectly fine in
WebKit-based browsers.

For example, compare the playback of
https://www.youtube.com/watch?v=K0Tsa3smr1w on Firefox at 3.5 speed v
the same on Safari: audio on Safari is much smoother than FF, especially
since FF skips audio every few seconds. Human speech is practically
undescipherable on FF, but is smooth on Safari.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/4

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On 2018-01-10T03:59:04+00:00 Suro001 wrote:

Can you launch firefox from the console by doing:
MOZ_LOG=MediaDecoder:4,AudioStream:3 path/to/your/firefox "https://www.youtube.com/watch?v=K0Tsa3smr1w"

and submit the logs?

Thanks!

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/5

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On 2018-01-10T09:33:28+00:00 S-bugzilla-mozilla wrote:

Created attachment 8941359
fflog.log

Log from `MOZ_LOG=MediaDecoder:4,AudioStream:3
/Applications/Firefox.app/Contents/MacOS/firefox
"https://www.youtube.com/watch?v=K0Tsa3smr1w"`

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https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/6

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On 2018-02-20T18:56:39+00:00 Giles-d wrote:

Bryce, do you have any interest in the playback rate stuff?

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/7

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On 2018-02-23T16:33:32+00:00 Bvandyk-0 wrote:

:rillian, I've taken a look and can't repro thus far. I'm going to hold
the needinfo while I wait for some new hardware to arrive and then I'll
be able to test this on OSX and see if I have any more luck.

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https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/8

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On 2018-04-11T15:36:00+00:00 Bvandyk-0 wrote:

I've been unable to repro this on OSX and a couple of other systems I've
tested.

Isaac, are you still seeing issue? If so, could you please gather a log
using MOZ_LOG=MediaFormatReader:5?

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/9

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On 2018-04-12T04:45:55+00:00 S-bugzilla-mozilla wrote:

Created attachment 8967249
newlog.log.gz

Log from `MOZ_LOG=MediaFormatReader:5 /Applications/Firefox\ Developer\
Edition.app/Contents/MacOS/firefox-bin`

I changed the playback rate about 5-10 secs into the video playing

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/10

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On 2018-04-12T04:51:46+00:00 S-bugzilla-mozilla wrote:

Created attachment 8967250
firefox.mp3

A loopback recording of https://www.youtube.com/watch?v=UzsnzeaOD84
played at 4x speed from firefox. I have the raw wav file if needed.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/11

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On 2018-04-12T04:52:28+00:00 S-bugzilla-mozilla wrote:

Created attachment 8967251
opera.mp3

A loopback recording of https://www.youtube.com/watch?v=UzsnzeaOD84
played at 4x speed from Opera. I have the raw wav file if needed for
further analysis.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/12

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On 2018-04-12T04:55:21+00:00 S-bugzilla-mozilla wrote:

If you play the recording from firefox, you can see that the words are
mangled, compared to that from Opera. You can clearly tell that some
audio segments are completely skipped over if you slow down the
playback. The audio from Opera isn't that different, from what I can
hear, to that of Chrome's. I haven't tested it on Safari.

I can upload wav files for analysis if you need them.

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https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/13

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On 2018-05-20T09:43:50+00:00 S-bugzilla-mozilla wrote:

I can reproduce this bug on version 61.0b6, currently the latest release
for Developer Edition.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/14

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On 2018-07-16T03:59:25+00:00 Alex Korchemniy wrote:

This is the #1 reason I don't use Firefox for YouTube. Chrome plays back
audio smoothly at 4x. Firefox sounds like it's dropping samples after
2x. This might not be problematic for music, but extremely problematic
for speech.

I started digging into the Firefox code for playback adjustments. It
looks like Firefox uses the SoundTouch library: https://dxr.mozilla.org
/mozilla-central/source/media/libsoundtouch/src/RateTransposer.h. I'm
not sure if this bug exists upstream.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/16

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On 2018-09-15T12:22:56+00:00 Plurtu wrote:

I did a visual comparison of the two samples in Audacity and while they
look similar there are occasionally dropped words which are detectable
in playback. For example 8 seconds into the Firefox sample (27 seconds
in original) is the line "So for people who don't know" and the word
"for" is missing.

The intro tune at 5 seconds has a wavy max amplitude when it should be
relatively flat and have a faster beat.

I recorded my own sample on Nightly 64 Ubuntu 18.04 and was able to
reproduce the issue.

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https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/18

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On 2018-09-15T12:24:34+00:00 Plurtu wrote:

Created attachment 9009353
missing-word.png

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/19

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On 2018-09-15T12:25:11+00:00 Plurtu wrote:

Created attachment 9009354
wavy-intro-tune.png

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/20

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On 2018-12-27T05:29:35+00:00 Plurtu wrote:

*** Bug 1515054 has been marked as a duplicate of this bug. ***

Reply at:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1654480/comments/21

** Changed in: firefox
       Status: Unknown => Confirmed

** Changed in: firefox
   Importance: Unknown => Medium

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Title:
  HTML5 sound choppy when played at 4x

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