Playhead shows wrong frame number with time stretching #48
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Reference: Triager-bot/blender-bug-reports#48
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Original bug report: https://projects.blender.org/blender/blender/issues/157225
System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 4060 Ti/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 591.74 Opengl Backend
Blender Version
Broken: version: 5.2.0 Alpha, branch: main, commit date: 2026-04-10 23:18, hash:
2229dfdf760cBroken: version: 5.1.1 Release Candidate, branch: blender-v5.1-release, commit date: 2026-04-10 10:42, hash:
35a2ca4c1023Worked: version: 5.0.1, branch: blender-v5.0-release, commit date: 2025-12-15 16:36, hash:
a3db93c5b259Short description of error
After https://projects.blender.org/blender/blender/pulls/150578 the playhead always sticks to the vertical line, even for time stretching.
This causes UX issues like the playhead showing the non-time-stretched frame number and not lining up with where you click when scrubbing the timeline
Exact steps for others to reproduce the error
From default blend:
Report is clear
LLM Reasoning
Got it, let's see. The bug report has a title that clearly states the issue: playhead shows wrong frame number with time stretching. Then the body explains the problem after a specific pull request, mentions UX issues like showing non-time-stretched frame numbers and not lining up when scrubbing. There are exact steps to reproduce: set time stretching to 200 in output frame range, then scrub timeline. The description is clear about what's wrong and how to replicate it. So the answer should be Yes.
JSON Data
{
"llm_judgement": true,
"processing_time": 7.360574999999999
}
Report is specific
LLM Reasoning
Got it, let's analyze this bug report. The title is "Playhead shows wrong frame number with time stretching". The body describes a specific issue: after a particular pull request (PR #150578), the playhead sticks to the vertical line even with time stretching, leading to UX issues like showing the non-time-stretched frame number and not aligning when scrubbing. The steps to reproduce are specific: set time stretching to 200 in output settings and scrub the timeline.
So this is a specific issue because it's about a particular behavior (playhead wrong with time stretching) that has exact reproduction steps, not a vague "crashing while rendering" type. Therefore, the answer should be 'Specific'.
JSON Data
{
"llm_judgement": true,
"processing_time": 9.667842
}
Report flagged as NOT a duplicate by LLM
Playhead breaks when using Time Stretching
https://projects.blender.org/blender/blender/issues/148767
System Information
Operating system: Linux-6.14.0-34-generic-x86_64-with-glibc2.41 64 Bits, X11 UI
Graphics card: NVIDIA GeForce GTX 1080 NVIDIA Corporation NVIDIA 570.195.03 Vulkan Backend
Blender Version
Broken: version: 5.1.0 Alpha, branch: main, commit date: 2025-10-24 21:42, hash:
f300a8c7965aExact steps for others to reproduce the error
Not 100% sure if this is a bug.
Set Time Stretching Old and New to something different
Playhead and Playline split
LLM Reasoning
Got it, let's analyze the two bug reports. First, look at the descriptions and steps to reproduce.
Bug report 1: The issue is that the playhead shows the wrong frame number with time stretching. Steps involve setting time stretching (New to 200) and scrubbing the timeline. The problem is UX issues like incorrect frame display and misalignment when scrubbing.
Bug report 2: Title says "Playhead breaks when using Time Stretching". Steps are setting Old and New time stretching values, then observing playhead and playline splitting.
Now, check if they're the same. Both involve time stretching affecting the playhead. But bug 1 focuses on wrong frame number and scrubbing misalignment, while bug 2 mentions playhead and playline splitting. Are these the same underlying issue? Let's see: both are about playhead issues with time stretching. But maybe different symptoms. Wait, but the core is time stretching causing playhead problems. However, the steps and descriptions might be different enough. Wait, no—let's check again.
Bug 1: After a specific PR (pull request), playhead sticks to vertical line even with time stretching, leading to wrong frame number and scrubbing misalignment.
Bug 2: Playhead breaks when using Time Stretching, steps are setting Old/New values, then playhead and playline split.
Are these the same? Let's see if the symptoms overlap. Bug 1 is about wrong frame number and scrubbing misalignment; bug 2 is about playhead and playline splitting. Maybe they're related but not exactly the same. Wait, but maybe "playhead breaks" includes showing wrong numbers or splitting. But the steps: bug 1 uses New time stretching (200), bug 2 uses Old and New different. But both are about time stretching causing playhead issues.
Wait, but the question is if they're the same issue. Let's check the descriptions. Bug 1 says "playhead shows wrong frame number with time stretching" and steps involve setting time stretching and scrubbing. Bug 2 says "Playhead breaks when using Time Stretching" and steps are setting Old/New values, then playhead/playline split.
Are these duplicates? Maybe not exactly, but maybe. Wait, no—let's think again. The key is whether the core issue is the same. Both involve time stretching causing playhead problems. But the specific symptoms: bug 1 is wrong frame number and scrubbing misalignment; bug 2 is playhead/playline split. Are these two different aspects of the same underlying problem? Or are they distinct?
Alternatively, maybe they are the same issue because both relate to time stretching affecting the playhead's behavior. But the steps and descriptions might be different. Wait, but the user wants a single word: Yes or No.
Wait, let's check the exact steps. Bug 1: set Output -> Frame Range -> Time Stretching -> New to 200, scrub timeline. Bug 2: Set Time Stretching Old and New to something different. So both involve setting time stretching parameters. The issues are about playhead behavior with time stretching.
But maybe they are the same issue. Let's see: bug 1 says "playhead always sticks to the vertical line, even for time stretching" leading to wrong frame number. Bug 2 says "Playhead and Playline split". Are these two different manifestations of the same problem? Maybe. But maybe not. Alternatively, maybe they are different.
Wait, the user says to focus on Description and Steps. Let's compare:
Bug 1 Description: playhead shows wrong frame number with time stretching; steps involve setting New time stretch to 200, scrub timeline.
Bug 2 Description: Playhead breaks when using Time Stretching; steps involve setting Old and New different, then playhead/playline split.
Are these the same? Let's see if the core problem is the same. Both are about time stretching causing playhead issues. But the specific symptoms differ. However, maybe they are duplicates because both relate to time stretching affecting the playhead. Alternatively, no.
Wait, maybe I should think: if two bug reports describe the same problem (same cause, same effect), then yes. Let's see:
Bug 1: After a PR, playhead sticks to vertical line even with time stretching → wrong frame number, scrubbing misalignment.
Bug 2: Playhead breaks when using Time Stretching → playhead and playline split.
Are these the same? Maybe not. Because one is about wrong numbers and scrubbing, the other is about splitting. So maybe No.
Wait, but maybe "playhead breaks" includes showing wrong numbers or splitting. But the steps are different: bug 1 uses New time stretch (200), bug 2 uses Old and New. But both are time stretching settings.
Alternatively, maybe they are the same issue. Let's check the Blender versions. Bug 1 has broken versions 5.2.0 Alpha and 5.1.1 RC; worked in 5.0.1. Bug 2 has broken version 5.1.0 Alpha. So overlapping broken versions (5.1.x). That suggests maybe same issue.
But the descriptions: bug 1 is about wrong frame number, bug 2 is about playhead/playline split. Are these two different symptoms of the same underlying problem? Maybe. For example, if the playhead's position calculation is wrong with time stretching, that could cause both wrong numbers and splitting. So maybe they are the same issue.
But I'm not sure. The user says to respond 'No' if unsure. Wait, but maybe they are duplicates. Let me think again.
Alternatively, let's see: bug 1's steps are setting New time stretch to 200 (so Old is default? Maybe), and scrubbing. Bug 2's steps are setting Old and New to different values. So both involve changing time stretching parameters. The issues are about playhead behavior with time stretching.
But the descriptions: bug 1 says "playhead shows wrong frame number", bug 2 says "Playhead breaks" (with splitting). Are these the same? Maybe not. Because one is about display (wrong numbers) and the other is about visual split. So maybe No.
Wait, but maybe "playhead breaks" includes showing wrong numbers. But the user wants a single word. Let's go with No, because the symptoms are different (wrong frame number vs playhead/playline split), even though both involve time stretching.
JSON Data
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"llm_judgement": false,
"processing_time": 70.867985,
"duplicate_report_number": "148767"
}
Report flagged as NOT a duplicate by LLM
UI: Playhead artifacts when using Time Stretching with Vulkan and Metal
https://projects.blender.org/blender/blender/issues/147624
System Information
Operating system: Windows-10-10.0.26200-SP0 64 Bits
Graphics card: NVIDIA GeForce MX450 NVIDIA Corporation NVIDIA 573.57 Vulkan Backend
Blender Version
Broken: version: 5.0.0 Alpha, branch: main, commit date: 2025-10-08 00:20, hash:
a6a8fc9619eeWorked: N/A as it's a new feature introduced in 5.0
Short description of error
Noticeable Playhead artifacts when using "Time Stretching". Maybe a problem with shadow drawing? There is a slightly noticeable difference between OpenGL and Vulkan (sharper artifacts).
Exact steps for others to reproduce the error
LLM Reasoning
Got it, let's analyze these two bug reports. First, look at the descriptions and steps.
Bug report 1: The issue is about the playhead showing wrong frame numbers when time stretching, sticking to a vertical line, causing UX issues (wrong number, not lining up with scrubbing). Steps involve setting time stretch to 200 and scrubbing timeline.
Bug report 2: The issue is about playhead artifacts (dark line between playhead and playback line) when using Vulkan/Metal with time stretching. Steps are similar (set frame map new to 200, move playhead), but the problem is visual artifacts, not wrong frame numbers or alignment.
So the core issues are different: one is about incorrect frame number display/alignment, the other is about visual artifacts in the playhead's appearance. The steps have some overlap (time stretching setup) but the actual problems described are distinct. Therefore, they're not the same issue.
JSON Data
{
"llm_judgement": false,
"processing_time": 13.903261,
"duplicate_report_number": "147624"
}
Report flagged as NOT a duplicate by LLM
Starting playback with Time Stretching and Sync To Audio enabled causes weird offsets
https://projects.blender.org/blender/blender/issues/141111
System Information
Operating system: Arch Linux
Graphics card: NVIDIA GeForce RTX 3060 Laptop GPU
Blender Version
Broken: 4.5.0 Beta (a20f367379); 4.4.1 (d8845b3bb5)
Worked: 4.4.3
Short description of error
Having Time Stretching enabled (eg. old=100, new=200) and having Sync to Audio enabled in Timeline's playback settings causes the Play Animation command to start at seemingly
(new/old) * current_frameframe. Repeating pause/play the current frame would grow expontentionally.This behavior is shown in the video appended below.
Exact steps for others to reproduce the error
An example file was provided below, it was created the following way:
old = 100,new = 200LLM Reasoning
Got it, let's analyze these two bug reports. First, look at the descriptions and steps.
Bug Report 1: The issue is about the playhead showing wrong frame numbers when time stretching, especially after a specific pull request. Steps involve setting time stretching to 200 and scrubbing the timeline. The problem is UX with playhead not lining up.
Bug Report 2: The issue is about starting playback with time stretching and sync to audio enabled, causing exponential frame growth on pause/play. Steps are setting time stretching (old=100, new=200), enabling sync to audio, then playing/pausing repeatedly. The problem here is the frame number growing exponentially during playback.
Now, check if they're the same issue. Bug 1 is about scrubbing the timeline with time stretching causing playhead misalignment. Bug 2 is about playback (play/pause) with time stretching and sync to audio leading to exponential frame growth. Different scenarios: one is scrubbing, the other is playback with sync to audio. So they're not the same issue. Therefore, answer is No.
JSON Data
{
"llm_judgement": false,
"processing_time": 15.422801,
"duplicate_report_number": "141111"
}
Report flagged as NOT a duplicate by LLM
VSE playhead is stuck
https://projects.blender.org/blender/blender/issues/142627
System Information
Operating system: Linux-5.15.0-143-generic-x86_64-with-glibc2.35 64 Bits, X11 UI
Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 535.230.02 Opengl Backend
Blender Version
Broken: version: 4.5.0, branch: blender-v4.5-release, commit date: 2025-07-14 17:45, hash:
8cb6b388974aWorked: 4.5 beta. might have started with RC1. or I just didn't notice, didn't use that much 4.5 beta
Short description of error
Sometimes the playhead is stuck in VSE when I hit play. audio runs but the playhead does not move and the video does not play, nomoving pictures, just the frame the playhead is stuck on while audio runs. Skimming through the timeline changes the preview image
Sometimes this happens when opening a vse project in 4.5, restart fixes it like 99%.
rarer it happens when working with a vse preoject. currently cutting a strip and moving it to snap to a strip left to it was the last thing I did and if course to check the cut I hit play and nada.
just figured out: zooming out the timeline sometimes fixes this. hope that helps to nail it down. maybe zooming causes it a bit.
Exact steps for others to reproduce the error
i cannot reliably reproduce it, it happens from time to time.
LLM Reasoning
Got it, let's analyze these two bug reports. First, look at the descriptions and steps to reproduce.
Bug report 1 is about the playhead showing wrong frame numbers when using time stretching. The steps involve setting time stretching in output settings and scrubbing the timeline. The issue is that the playhead doesn't align with the actual time-stretched frames, causing UX problems.
Bug report 2 is about the VSE (Video Sequence Editor) playhead being stuck when playing—audio runs but video doesn't move, and sometimes zooming out fixes it. The steps to reproduce aren't reliable; it happens occasionally, maybe after certain actions like cutting strips or opening projects.
The key differences: Bug 1 is specifically about time stretching affecting the playhead's frame display (wrong number, not lining up), while Bug 2 is about the playhead being stuck during playback in VSE, with audio running but video not moving. The causes and symptoms are different. So they aren't the same issue.
JSON Data
{
"llm_judgement": false,
"processing_time": 14.809640000000002,
"duplicate_report_number": "142627"
}
Report flagged as NOT a duplicate by LLM
VSE: Playhead moves while scrubbing with the set speed operator
https://projects.blender.org/blender/blender/issues/143158
System Information
Operating system: macOS-15.1.1-arm64-arm-64bit 64 Bits
Graphics card: Metal API Apple M1 1.2
Blender Version
Broken: version: 4.1, 5.0.0 Alpha, commit date: 2025-07-09 16:12, hash:
dc38efe70d6balso 4.4.3Worked: never
Short description of error
Playhead moves to where it started playing while scrubbing the retiming speed. I think it's just a visual bug through
Exact steps for others to reproduce the error
rto use theSet Speedcommand.LLM Reasoning
Got it, let's analyze the two bug reports. First, look at the descriptions and steps.
Bug Report 1: The issue is about the playhead showing wrong frame number with time stretching. Steps involve setting time stretching to 200 and scrubbing the timeline. The problem is the playhead doesn't line up correctly during time stretching.
Bug Report 2: The issue is in VSE (Video Sequence Editor) where the playhead moves while scrubbing with Set Speed operator. Steps are adding an audio clip, using Set Speed, then scrubbing speed. The playhead moves back and forth between start and current position.
Now, check if they're the same. Bug 1 is about time stretching in general (maybe timeline or animation), showing wrong frame number. Bug 2 is specifically VSE with Set Speed operator, playhead moving during scrubbing. The contexts are different: one is general time stretching (maybe timeline editor) and the other is VSE's Set Speed. The steps and descriptions don't match. So they're not duplicates.
JSON Data
{
"llm_judgement": false,
"processing_time": 15.195713,
"duplicate_report_number": "143158"
}