Bug 287434 – Replaying video in Safari can seek to random non-zero time followed by 'timeupdate' at zero

• Status: NEW
• Component: Media

[Rob Smith]

Created attachment 474190 [details]
Event log showing that a 'timeupdate' event at zero follows the non-zero 'seeked' event

# Description

Replaying video in Safari can seek to random non-zero time followed by 'timeupdate' at zero

# Steps to reproduce

1. Load the video in the web page attached to see the event log.
2. Press the Safari play control to play the video to the end (only 5 secs long).
3. Note that 'timeupdate' event times increase monotonically in the event log.
4. Repeat step 2.
5. Note that the time for the 'seeking' event is always zero.
6. Note that the time for the 'seeked' event may be randomly zero or a small non-zero value. Highest observed time is 0.014 seconds and values appear to be random.
7. Note that a 'timeupdate' event at zero follows the non-zero 'seeked' event - see example screenshot.
8. If a zero 'seeked' time is observed, repeat from step 4. This error is not 100% reproducible but should occur at least once with 10 retries. Please be persistent.

# Expected result

Replaying a video should always seek to time zero. Times of subsequent 'timeupdate' events should increase monotonically from the 'seeked' event time.

The expected result is observed when the test is performed using either Firefox 128.5.2esr(64-bit) or Chrome 131.0.6778.140.

# Actual result

Replaying a video does not always seek to time zero when the video is played in Safari 18.2(20620.1.16.11.8). A 'timeupdate' event with time zero always occurs after the non-zero 'seeked' event time.

# Further details

This issue may be related to issue 287430: "Playing video in Safari can generate non-monotonic 'timeupdate' events". This behaviour is not unique to the example video file provided.

[Rob Smith]

Created attachment 474191 [details]
Sample web page used to demonstrate bug and generate screenshot

[Radar WebKit Bug Importer]

<rdar://problem/145006171>