WebTorrent: Autoplay is sometimes blocked if media metadata is not ready yet

[feross]

Description

If the media element does not have metadata available immediately when the media viewer loads, then autoplay will fail with a DOMException.

Steps to Reproduce

1. Load the torrent from https://ia802608.us.archive.org/18/items/gd1975-06-17.aud.unknown.87560.flac16/gd1975-06-17.aud.unknown.87560.flac16_archive.torrent
2. Start the download.
3. Scroll to the bottom of the file list and select the last MP3 file in the list (file number 111). (This is so that the file data is not likely to be downloaded by webtorrent yet.)
4. The file should eventually start playing. There should be no warning that autoplay was blocked.

Actual result:

Media sometimes does not autoplay.

Expected result:

Media should always autoplay.

Reproduces how often:

Intermittent issue

Brave version (brave://version info)

master

[kjozwiak]

@feross looks like this is still happening here and there. It takes a few tries to reproduce on a new profile, but you'll eventually run into the following:

Used the following build:

Brave	0.69.128 Chromium: 77.0.3865.75 (Official Build) (64-bit)
Revision	201e747d032611c5f2785cae06e894cf85be7f8a-refs/branch-heads/3865@{#776}
OS	macOS Version 10.14.6 (Build 18G95)

I couldn't reproduce the above using https://webtorrent.io/torrents/wired-cd.torrent though. Maybe it's based on timing? I was running through the case pretty quickly. We can definitely label this as verified as it's a big improvement compared the previous behaviouor. @feross thoughts?

[feross]

Yeah, I noticed this as well. The fix felt a little hacky, but it now works like 95% of the time, which is better than 0%. I wish there was some easy way to just disable autoplay policy for the WebTorrent extension. I wonder if @yrliou has any ideas how to do this or who to ask.

[rebron]

@darkdh suggestions for this one?

[darkdh]

We have autoplay whitelist (https://github.com/brave/autoplay-whitelist) but it only support url host right now (https://github.com/brave/autoplay-whitelist/blob/master/data/autoplay.json)
Maybe we can make it support extension id like webtorrent's case
chrome-extension://lgjmpdmojkpocjcopdikifhejkkjglho/extension/brave_webtorrent.html?https://webtorrent.io/torrents/wired-cd.torrent

[darkdh]

For example, I added webtorrent to autoplay content setting like this


This allows any media from webtorrent to autoplay.

[kjozwiak]

I can confirm that adding chrome-extension://lgjmpdmojkpocjcopdikifhejkkjglho/ into the auto play content settings fixes what I ran into #5471 (comment). Couldn't reproduce the issue after several attempts.

[kjozwiak]

@rebron @darkdh should we create a new issue for adding the ability to add extensions into the autoplay whitelist? We can continue verifying this one as it works ~95% of the time and can address the issue in more detail in another GH. Thoughts?

[feross]

should we create a new issue for adding the ability to add extensions into the autoplay whitelist?

Didn't you say that you were already able to add the WebTorrent extension URL into the whitelist? So shouldn't the issue actually be to add WebTorrent to the list by default?

[darkdh]

The thing we added above is "Content Setting", the brave autoplay list is beyond that.
Every time autoplay permission request coming, we check brave autoplay whitelist first and then check content setting if host doesn't match anything in the whitelist

[feross]

@darkdh Thanks for explaining the distinction. Makes sense!

[btlechowski]

Verification passed on

Brave	0.69.129 Chromium: 77.0.3865.90 (Official Build) (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	Ubuntu 18.04 LTS

The issue still reproduces. Logged #6195.

Verification PASSED on macOS 10.14.6 x64 using the following build:

Brave	0.69.129 Chromium: 77.0.3865.90 (Official Build) (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	macOS Version 10.14.6 (Build 18G95)

• Verified the STR/test case outlined under WebTorrent: Autoplay is sometimes blocked if media metadata is not ready yet #5471 (comment)

Verification passed on

Brave	0.69.130 Chromium: 77.0.3865.90 (Official Build) (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified the STR/test case outlined under WebTorrent: Autoplay is sometimes blocked if media metadata is not ready yet #5471 (comment)