Bug 212131 – REGRESSION (iOS 13.4): Audio drift on HLS videos that encrypted with AES-128

• Status: RESOLVED
• Resolution: MOVED
• Component: Media

[Jatesadakarn Saengrat]

Created attachment 399825 [details]
Some error message when drifting happens

We found that playing HLS videos (MPEGTS segments) that encrypted with AES-128,
on Safari on iOS 13.4, has some video/audio out-of-sync issues:

1. The video starts normally, no out-of-sync issues.
2. As the video playing, the audio keep out-of-sync, ahead of the video incrementally.
3. If user seek the video, the audio will back to be sync with the video again.
4. The drifting will occur again after a while.

We already investigate that:

* No drifting on older iOS versions.
* No drifting on iOS 13.4 with unencrypted HLS videos.
* No drifting on iOS 13.4 if the video is forced to play with MSE (on iPadOS).
* Also found this issue on Safari 13.2 (WebKit 15610.1.12.2) on Mac OS X.

When this issue occurs, there are some error log like this from mediaserverd:

Too few bits left in input buffer
Error deserializing packet
ACMP4AACBaseDecoder.cpp:1392:ProduceOutputBufferList: (0x159637640) Error decoding packet 2583: err = -1, packet length: 371
ACMP4AACBaseDecoder.cpp:1401:ProduceOutputBufferList: '21 11 45 00 14 50 01 46 FF F1 0A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5A 5D E9 82 14 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 B4 47 40 11 1A 00 42 F0 25'

We also prepare sample videos for reproducing this issue:
* Encrypted HLS video (that the drifting occurs):
    * Media: https://champjss-apple-hls-sync-issues.sgp1.cdn.digitaloceanspaces.com/blip-blop/encrypted/prog_index.m3u8
    * Sample Experience: https://youtu.be/y_9CQSfjRwY
* Unencrypted HLS video:
    * Media: https://champjss-apple-hls-sync-issues.sgp1.cdn.digitaloceanspaces.com/blip-blop/raw/prog_index.m3u8
    * Sample Experience: https://youtu.be/0HG_lpcR0Mc

[Radar WebKit Bug Importer]

<rdar://problem/63469191>

[Yuta Naito]

*** Bug 212472 has been marked as a duplicate of this bug. ***

[Nonthawat Srichad]

Hi,

Thanks, Yuta for update your issue. :)


Here is updated information from our side

1. We have tested on iOS 13.5 and confirm that it still exists both iPhone and iPad.

2. We also discovered that this bug is occurring on macOS Catalina 10.15.5 too. tested on 
- Safari Version 13.1.1 (15609.2.9.1.2)
- Safari Technology Preview Release 107 (Safari 13.2, WebKit 15610.1.14.1)


If you want more information or log feel free to contact me or Jatesadakarn.

[Yuta Naito]

Hi, Nonthawat.

Thanks for the additional information.
I've seen it happened in my own iOS 13.5 and Safari Technology Preview Release 107.
I'll let you know if I want more information.

--

Dear Webkit developer
This issue has a huge impact on our business.
I hope you can fix it as soon as possible..

Or do you have other workarounds or something like that?

[Jatesadakarn Saengrat]

HTML page for demonstration.
https://champjss-apple-hls-sync-issues.sgp1.cdn.digitaloceanspaces.com/blip-blop/index.html

I am also experiencing the same issues.

Happy to provide further information if needed.

[Jon Lee]

This is an issue on system frameworks.

Please try the latest iOS 13.5.5 beta.

[Nonthawat Srichad]

Hi Jon Lee,

Thanks for the update. But you mention about beta version for iOS/iPadOS what about Safari on macOS? it also has the same issue as iOS/iPadOS.

Anyway, I will try the iOS beta version and let you know the result.

[Nonthawat Srichad]

Hi all,

We've tested on iOS/iPadOS 13.6 beta (13.5.5 beta?) using a link from Jatesadakarn's comment and confirm that this issue is solved. 

- No audio drift occurs when playing encrypted HLS video (VOD).
- No error deserializing packet occurs.

[Yasuhiko Takano]

Hello, I had same problem.

(refer https://bugs.webkit.org/show_bug.cgi?id=212588)

and I tested with below URL 

target URL: https://5aeb1e45d40a5.streamlock.net/vodcf6/sync.mp4/playlist.m3u8

with 13.6 public beta2 and iPad 7th generation 

and the issue was solved.

[Yasuhiko Takano]

I also checked with
 
https://champjss-apple-hls-sync-issues.sgp1.cdn.digitaloceanspaces.com/blip-blop/index.html

and iPad7 + 13.6 public beta2 and iPad 7th generation,

and the issue was solved on it.