1955763 - h265/hevc videos on TikTok drop a lot of frames

Status: UNCONFIRMED

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

Description

[tgn-ff]

Steps to reproduce:

I'm using Linux and Nightly.

1. Visit a TikTok channel.
2. Click on the first video and scroll to watch a few more.

Actual results:

There are a lot of dropped frames. The video stays to a still image every few seconds for a while. Setting media.hevc.enabled:false workarounds the issue.

The following logs are from two different videos. Note that both profiles show the playback of only one video, but I had to play at least one before that in order for the issue to reproduce.

https://share.firefox.dev/4kViFuH
https://share.firefox.dev/4hAgIRr

Expected results:

See also: Bug 1954323. Not sure if this is an issue on TikTok only, btw.

Comment 1

[Alastor Wu [:alwu]]

When using hardware decoding, I can't reproduce this issue on my Windows and MacOS. On my Linux, it's sw decoding due to the Nvidia card issue, but sw decoding doesn't have problem for me as well. Can you try to disable the pref media.hardware-video-decoding.enabled and restart Firefox to see if the issue still exists? Thanks!

Comment 2

[tgn-ff]

Yes, I can reproduce it with hardware acceleration disabled or even in safe mode. Keep in mind, when I say scroll to watch a few videos, you need to let them play. I can reliably reproduce it in a clean profile (the logs are from a clean profile) after watching fewer than five or six videos of about 15-60sec each.

Comment 3

[Alastor Wu [:alwu]]

Could you help me capture a media profile for SW decoding as well? I tried to let every video play to the end, then scroll to next one, but still no luck to reproduce. I also confirmed every videos I played were HEVC. What is the version of your system ffmpeg? will you see stuttering on these hevc videos as well? (but some HEVC videos on that page are not supported) Thanks!

Comment 4

[tgn-ff]

Here is a profile with SW decoding using the same video as in the first of the two profiles I shared before: https://share.firefox.dev/4hBGCnZ.

I'm on ArchLinux/KDE/X11. ffmpeg is at 7.1, but I have the 4.4.5 version installed as a dependency. I removed 4.4.5 and was still able to reproduce it, but all the profiles I provided are with it installed.

I don't see any dropped frames on those samples (tried quite a few), that's why I mentioned that this might be specific to TikTok. Even on TikTok, if I click directly on a video that I know it had the issue before, it won't reproduce.

Comment 5

[Kevin Pachuca]

Using Firefox Nightly 140.0a1: This issue still persists as described from user tgn-ff. I have used a clean firefox profile and viewed videos off a tiktok profile that still stutters after a couple 2, 13+ sec videos.

Comment 6

[Alastor Wu [:alwu]]

Are you also on Linux? Could you capture a profile per this instruction as well? Thanks!

Comment 7

[Kevin Pachuca]

(In reply to Alastor Wu [:alwu] from comment #6)

Are you also on Linux? Could you capture a profile per this instruction as well? Thanks!

I'm on Windows 11 home 24H2 using Firefox Nightly 140.0a1,

To reproduce this I go into my profile where I can view saved videos from other creators and just go through each video. After I go through a couple videos that are 13secs+, my video's start lagging/stuttering after the 13secs.

Capture Profile: https://share.firefox.dev/44Ucu4i

Comment 8

[Kevin Pachuca]

Given time, I can give a better bug report about the dropped frames on H.265/HEVC Tiktok videos.

Environment:
Operating system: Windows 11 25H2
Firefox version: Nightly 142.0a1 (2025-07-12) (64-bit)

Steps to reproduce:

1. Go to either of these 3 links;

• https://www.tiktok.com/@twlxty/video/7526112040709131576
• https://www.tiktok.com/@heosan/video/7525849848835280136
• https://www.tiktok.com/@zefeng_tt/video/7515894407074352430

2. Open the user profile of the video
3. Click the video associated with the link/video you clicked on in step 1
4. Observe the video for dropped frames

Expected Results:
Video playback is displayed correctly

Actual Results:
There is stutters or frame drops during video playback

Capture Profile:
https://share.firefox.dev/3U6ZmSG

Notes:

1. Video playback is normal and working from the link
2. The issue only happens when viewing the video within a Tiktok profile
3. Stutter/Frame drops are more persistent when big effects or transitions happen in the video
4. I got a recording of my test. I want to share it but I'm not sure how.