1511869 - Video playback freezes while audio still runs when going back around the start of the video

Status: RESOLVED INVALID

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

Description

[Paul_B]

Attachment: Video freez.mp4

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0
Build ID: 20181203093109

STR: 

1. Launch Firefox with a new profile.
2. Navigate to https://www.linkedin.com/learning/executive-leadership/welcome .
3. Click Play.
4. Reach the seek bar and click to 00.01.

ER:
The video and audio playback work properly when the user navigates the video using the seek bar. 

AR:
The video playback freezes from sec 00:01 until sec 00:10 while the audio runs properly. 
I have attached a short video for a better understanding of the issue. 

Note: I could not reproduce this issue on any other videos on the LinkedIn platform, other than the ones in Learning section.

Comment 1

[Paul_B]

The issue seems to be a regression, but I could not find the exact pushlog:  

Last good build: 91c2b9d5c1354ca79e5b174591dbb03b32b15bbf (build_date: 2016-09-07)
Pushlog: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=91c2b9d5c1354ca79e5b174591dbb03b32b15bbf&tochange=938ce16be25f9c551c19ef8938e8717ed3d41ff5

First bad build: 938ce16be25f9c551c19ef8938e8717ed3d41ff5 ( build_date: 2016-09-08)
Pushlog:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=dbe4b47941c7b3d6298a0ead5e40dd828096c808&tochange=938ce16be25f9c551c19ef8938e8717ed3d41ff5

Comment 2

[Andreas Pehrson [:pehrsons]]

Matthew, can you triage this?

Comment 3

[Andreas Pehrson [:pehrsons]]

Sorry, looked at the date of the wrong comment. jya, can you triage this?

Comment 4

[Liz Henry (:lizzard) (relman/hg->git project)]

Too late to fix in 63 or 64 but we could still take a patch for 66 or possibly 65.

Comment 5

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

Nils, I have heard that jya won't be back until the end of January. Is it possible for you to look in to this before then?

Comment 6

[Andreas Pehrson [:pehrsons]]

Chun-min, can you triage this instead?

Comment 7

[C.M.Chang[:chunmin] | PTO]

Sure, I'll see what I can do.

Comment 8

[C.M.Chang[:chunmin] | PTO]

The file format is MP4. Except the duration from 1 second to 9 (or 10, not sure) seconds, the seek works fine. The video will freeze if I seek to 5 from 0, or from 20 to 8. The video will freeze if it's seeked to somewhere between 1 to 9(or 10).

I noticed that the screen is always the same one. It's not the screen before seeking, nor the screen for the seeked point. It's always the same one. It looks like it's the frame near 9 or 10, which is the point about being able to play.

I download it then play the local file, the problem still exists, so it's not the EME case.

Bryce, any idea?

Comment 9

[C.M.Chang[:chunmin] | PTO]

Using mozregression to narrow down the range first

Comment 10

[Michael Froman [:mjf]]

Chun-Min, are you still looking into this?

Comment 11

[C.M.Chang[:chunmin] | PTO]

Yes, I suspected some commits that may cause this, but mozregression cannot catch the file more than one years ago. I tried jumping to the old commit to build the Firefox directly, but some of old code cause issues with the current build system(e.g., some Rust code were deprecated). I don't have much time for this, so feel free if anyone want to follow it.

Comment 12

[Neha Kochar [:neha]]

Nils, can you please have someone to look into this?

Comment 13

[Virginia (please send need info request to Brindusa Tot)]

Hi, this is still happening on the latest Nightly (68.0a1).
Are there any updates on this?

Thanks!

Comment 14

[Nils Ohlmeier [:drno]]

To clarify: I don't see this having anything to do with the Oculus Go problems in bug 1463904.

Chrome shows exactly the same problems with this video. Which makes me wonder if the file is encoded somehow badly.

On the other hand I verified that Firefox 47 can handle seeking in this file just fine.

jya any idea what could be going on here?

Comment 15

[Jean-Yves Avenard [:jya]]

Can't reproduce once the video is accessed locally or a local http server.

The issue appears to be with the server not supporting range request properly and I can reproduce the same issue in Chrome.