BlenderVSE: Seeking/Scrubbing issue #100495

New Issue

Michael · 2022-08-19T10:34:29+02:00

Michael commented

2022-08-19 10:34:29 +02:00

{F13403727}BasicEditingBug_Take2_ExaminingCuts.mp4

{F13403412}System Information
Operating system: Windows 10
Graphics card: Intel UHD Graphics 620

Other System Tested: Ubuntu 20.04, Nvidia RTX 3070

Blender Version
Broken: current release 3.2.2 and blender-3.4.0-alpha+master.2a2ca3292a93-linux.x86_64-release
Worked: I don't know
Note: Problem is much worse in 3.2.2, in 3.4 alpha it is better if you use refresh often.

When scrubing/searching the video frames get "shuffled around" leading to frames that are off/displaced, freeze frames, jumping frames etc. Doing exact cuts is not possible anymore.

Exact steps for others to reproduce the error
Watch my attached screencasts first (captured on windwos 10, 3.2.2). The longer video shows the steps to reproduce. The shorter video shows me examining the resulting cuts. All cuts are wrongly placed. At second 0:23 you see that frames are shuffled around between two scenes (even after a refresh)

The large video file is the sample file to work with when reproducing the bug. It was edited and rendered using VSE 2 years ago.

Instructions:

Open new video editing file (load factory settings)
Import the video file (EasyRobot_final.mp4)
Go to 4:53 and make split cuts (K) at each new scene.
use cursor keys for scrubbing (more scrubbing more problems, especially backward scrubbing).
when you cut the picture will jump or something else in the preview will change. no actual editing needed.
proceed doing cuts at each new scene trying to seperate them with split cuts.
After 5-6 cuts, play back the result. Preview will be a mess even without editing and cuts will not be in place where intended.
refresh only helps a little (helps more on 3.4)

Another way to see if the preview is off/messed up is by rendering a video of the portion you worked on. Overlay it with transparency and see if everything aligns. Frames will be off.

{[F13403727](https://archive.blender.org/developer/F13403727/EasyRobot_Final.mp4)}[BasicEditingBug_Take2_ExaminingCuts.mp4](https://archive.blender.org/developer/F13403417/BasicEditingBug_Take2_ExaminingCuts.mp4) {[F13403412](https://archive.blender.org/developer/F13403412/BasicEditingBug_take2.mp4)}**System Information** Operating system: Windows 10 Graphics card: Intel UHD Graphics 620 Other System Tested: Ubuntu 20.04, Nvidia RTX 3070 **Blender Version** Broken: current release 3.2.2 and blender-3.4.0-alpha+master.2a2ca3292a93-linux.x86_64-release Worked: I don't know Note: Problem is much worse in 3.2.2, in 3.4 alpha it is better if you use refresh often. When scrubing/searching the video frames get "shuffled around" leading to frames that are off/displaced, freeze frames, jumping frames etc. Doing exact cuts is not possible anymore. **Exact steps for others to reproduce the error** Watch my attached screencasts first (captured on windwos 10, 3.2.2). The longer video shows the steps to reproduce. The shorter video shows me examining the resulting cuts. All cuts are wrongly placed. At second 0:23 you see that frames are shuffled around between two scenes (even after a refresh) The large video file is the sample file to work with when reproducing the bug. It was edited and rendered using VSE 2 years ago. Instructions: - Open new video editing file (load factory settings) - Import the video file (EasyRobot_final.mp4) - Go to 4:53 and make split cuts (K) at each new scene. - use cursor keys for scrubbing (more scrubbing more problems, especially backward scrubbing). - when you cut the picture will jump or something else in the preview will change. no actual editing needed. - proceed doing cuts at each new scene trying to seperate them with split cuts. - After 5-6 cuts, play back the result. Preview will be a mess even without editing and cuts will not be in place where intended. - refresh only helps a little (helps more on 3.4) Another way to see if the preview is off/messed up is by rendering a video of the portion you worked on. Overlay it with transparency and see if everything aligns. Frames will be off. ``` ```

Michael commented

2022-08-19 10:34:29 +02:00

Added subscriber: @Michael-47

Michael commented

2022-08-19 11:07:56 +02:00

Added subscriber: @iss

Richard Antalik commented

2022-08-19 11:23:10 +02:00

Can you also upload .blend file?

I am mainly interested in state of proxy settings:

If you can't upload .blend file, please upload screenshot.

Can you also upload .blend file? I am mainly interested in state of proxy settings: ![Untitled.png](https://archive.blender.org/developer/F13404052/Untitled.png) If you can't upload .blend file, please upload screenshot.

Omar Emara commented

2022-08-19 11:48:45 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Richard Antalik commented

2022-08-19 11:50:38 +02:00

Changed status from 'Needs User Info' to: 'Confirmed'

Richard Antalik commented

2022-08-19 11:50:38 +02:00

@Michael-47 I was able to reproduce the issue, just quickly looking at debug output, seeking is definitely way off with this file. I am not sure why yet.
You have mentioned, that this is video rendered with Blender - is this original file you have stored on HDD or is it downloaded from some service like Youtube? Some(most?) of these services do re-encode original files to save up storage space and may do some tricks to optimize seeking perhaps. but I think they should still be playable.

So far I can only suggest workaround - build proxies and set them up as I have above in screenshot.

@Michael-47 I was able to reproduce the issue, just quickly looking at debug output, seeking is definitely way off with this file. I am not sure why yet. You have mentioned, that this is video rendered with Blender - is this original file you have stored on HDD or is it downloaded from some service like Youtube? Some(most?) of these services do re-encode original files to save up storage space and may do some tricks to optimize seeking perhaps. but I think they should still be playable. So far I can only suggest workaround - build proxies and set them up as I have above in screenshot.

Michael commented

2022-08-19 11:51:06 +02:00

here you go! a messed up file. only split cuts no editing done to it. all i did was performing the described steps from my bugreport.
to reproduce this bug i loaded factory settings!
When trying to work around this bug i tried everything i could think of. Proxies, No Proxies, Prefetch Frames, etc. No solution
SeekingIssueSampleFile.blend

here you go! a messed up file. only split cuts no editing done to it. all i did was performing the described steps from my bugreport. to reproduce this bug i loaded factory settings! When trying to work around this bug i tried everything i could think of. Proxies, No Proxies, Prefetch Frames, etc. No solution [SeekingIssueSampleFile.blend](https://archive.blender.org/developer/F13404111/SeekingIssueSampleFile.blend)

Michael commented

2022-08-19 11:55:08 +02:00

You have mentioned, that this is video rendered with Blender - is this original file you have stored on HDD or is it downloaded from some service like Youtube? Some(most?) of these services do re-encode original files to save up storage space and may do some tricks to optimize seeking perhaps. but I think they should still be playable.

Its the original render output from blender VSE. As render settings i use the preset provided by the power sequencer addon (Youtube Render Preset)

> You have mentioned, that this is video rendered with Blender - is this original file you have stored on HDD or is it downloaded from some service like Youtube? Some(most?) of these services do re-encode original files to save up storage space and may do some tricks to optimize seeking perhaps. but I think they should still be playable. Its the original render output from blender VSE. As render settings i use the preset provided by the power sequencer addon (Youtube Render Preset)

Richard Antalik commented

2022-08-19 12:57:49 +02:00

In #100495#1406008, @Michael-47 wrote:
When trying to work around this bug i tried everything i could think of. Proxies, No Proxies, Prefetch Frames, etc. No solution

Now checking with proxies, and there are indeed glitches, so that is no good.

In #100495#1406009, @Michael-47 wrote:

You have mentioned, that this is video rendered with Blender - is this original file you have stored on HDD or is it downloaded from some service like Youtube? Some(most?) of these services do re-encode original files to save up storage space and may do some tricks to optimize seeking perhaps. but I think they should still be playable.

Its the original render output from blender VSE. As render settings i use the preset provided by the power sequencer addon (Youtube Render Preset)

Haven't done any deep dive so far, but I have checked this file with 3 versions of ffplay (ffmpeg internal player) and with VLC, both failed and missed a lot of video frames when seeking to random positions. Looking at youtube preset of power sequencer now and I am pretty sure I have used nearly same settings 2 years ago too. Never saw problem like this though.

Further looking at metadata of provided file, they does not seem to come from Blender and audio bitrate does not match mentioned preset either:

$ ffprobe.exe T100495\ seek.mp4
...
[mov,mp4,m4a,3gp,3g2,mj2 @ 000001aedd13d080] st: 0 edit list: 2 Missing key frame while searching for timestamp: 0
[mov,mp4,m4a,3gp,3g2,mj2 @ 000001aedd13d080] st: 0 edit list 2 Cannot find an index entry before timestamp: 0.
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'T100495 seek.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 0
    compatible_brands: mp41avc1
    creation_time   : 2020-11-10T21:32:19.000000Z
    playback_requirements: QuickTime 6.0 or greater
    playback_requirements-eng: QuickTime 6.0 or greater
    encoder         : vlc 3.0.6 stream output
    encoder-eng     : vlc 3.0.6 stream output
  Duration: 00:11:54.71, start: 0.000000, bitrate: 11394 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 11194 kb/s, 25 fps, 25 tbr, 1000k tbn, 50 tbc (default)
    Metadata:
      creation_time   : 2020-11-10T21:32:19.000000Z
      handler_name    : VideoHandler
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      creation_time   : 2020-11-10T21:32:19.000000Z
      handler_name    : SoundHandler

For this case I would transcode provided file with command ffmpeg.exe -i bad_file.mp4 -c:v libx264 -crf 16 -g 10 fixed.mp4.

Do you remember on which OS this video was rendered? I am thinking, that it could have been rendered with Blender distributed through OS packaging system which could explain VLC encoder, but even this would be unlikely scenario I would say...

> In #100495#1406008, @Michael-47 wrote: > When trying to work around this bug i tried everything i could think of. Proxies, No Proxies, Prefetch Frames, etc. No solution Now checking with proxies, and there are indeed glitches, so that is no good. > In #100495#1406009, @Michael-47 wrote: >> You have mentioned, that this is video rendered with Blender - is this original file you have stored on HDD or is it downloaded from some service like Youtube? Some(most?) of these services do re-encode original files to save up storage space and may do some tricks to optimize seeking perhaps. but I think they should still be playable. > > Its the original render output from blender VSE. As render settings i use the preset provided by the power sequencer addon (Youtube Render Preset) Haven't done any deep dive so far, but I have checked this file with 3 versions of ffplay (ffmpeg internal player) and with VLC, both failed and missed a lot of video frames when seeking to random positions. Looking at youtube preset of power sequencer now and I am pretty sure I have used nearly same settings 2 years ago too. Never saw problem like this though. Further looking at metadata of provided file, they does not seem to come from Blender and audio bitrate does not match mentioned preset either: ``` $ ffprobe.exe T100495\ seek.mp4 ... [mov,mp4,m4a,3gp,3g2,mj2 @ 000001aedd13d080] st: 0 edit list: 2 Missing key frame while searching for timestamp: 0 [mov,mp4,m4a,3gp,3g2,mj2 @ 000001aedd13d080] st: 0 edit list 2 Cannot find an index entry before timestamp: 0. Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'T100495 seek.mp4': Metadata: major_brand : isom minor_version : 0 compatible_brands: mp41avc1 creation_time : 2020-11-10T21:32:19.000000Z playback_requirements: QuickTime 6.0 or greater playback_requirements-eng: QuickTime 6.0 or greater encoder : vlc 3.0.6 stream output encoder-eng : vlc 3.0.6 stream output Duration: 00:11:54.71, start: 0.000000, bitrate: 11394 kb/s Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 11194 kb/s, 25 fps, 25 tbr, 1000k tbn, 50 tbc (default) Metadata: creation_time : 2020-11-10T21:32:19.000000Z handler_name : VideoHandler Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default) Metadata: creation_time : 2020-11-10T21:32:19.000000Z handler_name : SoundHandler ``` For this case I would transcode provided file with command `ffmpeg.exe -i bad_file.mp4 -c:v libx264 -crf 16 -g 10 fixed.mp4`. Do you remember on which OS this video was rendered? I am thinking, that it could have been rendered with Blender distributed through OS packaging system which could explain VLC encoder, but even this would be unlikely scenario I would say...

Michael commented

2022-08-19 14:15:39 +02:00

the video was rendered with blender on windows 10. i usually use the render preset from power sequencer and i am pretty sure it was the case for this video as well. I found the 2year old projectfile. Here is a screenshot of the render settings:

one more thing: the first problems I had where with mp4 files from my camera. the problem is a little different but maybe it is related. I found rendered videos to show slightly different frames to the preview when importing the render result back into blender and overlaying it with 50% transparency. here is what i saw:

two frames that clearly are not the same and even a image render showed this (screenshot shows render image not preview!). however a video render of the original video and the renderresult overlayed with transparency did not show these ghostframes/difference.

the video was rendered with blender on windows 10. i usually use the render preset from power sequencer and i am pretty sure it was the case for this video as well. I found the 2year old projectfile. Here is a screenshot of the render settings: ![image.png](https://archive.blender.org/developer/F13404499/image.png) one more thing: the first problems I had where with mp4 files from my camera. the problem is a little different but maybe it is related. I found rendered videos to show slightly different frames to the preview when importing the render result back into blender and overlaying it with 50% transparency. here is what i saw: ![imageRender.jpg](https://archive.blender.org/developer/F13404480/imageRender.jpg) two frames that clearly are not the same and even a image render showed this (screenshot shows render image not preview!). however a video render of the original video and the renderresult overlayed with transparency did not show these ghostframes/difference.

Richard Antalik commented

2022-08-19 14:43:43 +02:00

Can you upload the original project file? I would like to reproduce this issue and fix encoder settings if this still happens. I need the file, because it should contain blender version it was last saved with, unless you re-saved file in newer one.

When movie is rendered, even if content is not correct, it must not affect integrity of rendered file. This seems to be caused by weird encoder settings somehow. Still this VLC encoder puzzles me though. I know, that Power Sequencer addon had feature, that can speed up rendering by splitting file into chunks and then joining them. Do you remember if you used this feature? maybe it is automatically used without asking, should look into that as well.

Can you upload the original project file? I would like to reproduce this issue and fix encoder settings if this still happens. I need the file, because it should contain blender version it was last saved with, unless you re-saved file in newer one. When movie is rendered, even if content is not correct, it must not affect integrity of rendered file. This seems to be caused by weird encoder settings somehow. Still this VLC encoder puzzles me though. I know, that Power Sequencer addon had feature, that can speed up rendering by splitting file into chunks and then joining them. Do you remember if you used this feature? maybe it is automatically used without asking, should look into that as well.

Michael commented

2022-08-19 14:58:22 +02:00

sorry if this is leading away from the orignal bug. i feel like it is related.

here is a broken file showing problems described above, with files straight from my camera (not rendered from blender). what you see is a clip of the original file overlayed by the render result with 50% transparency. When rendering this again what you get is the third clip on top. The third clip does not show ghostframes but the preview does and render image also does show a difference. frame 530 (21+05) is a good example. Along with the broke file comes the render output and the render output that i would have expect to show ghostframes/blury frames and the original file (4k from canon camera).

MVI_7312.MP4

lastSyncTest01.blend

lastSyncTest01_rendering01_blury.mp4

lastSyncTest01_rendering01.mp4

sorry if this is leading away from the orignal bug. i feel like it is related. here is a broken file showing problems described above, with files straight from my camera (not rendered from blender). what you see is a clip of the original file overlayed by the render result with 50% transparency. When rendering this again what you get is the third clip on top. The third clip does not show ghostframes but the preview does and render image also does show a difference. frame 530 (21+05) is a good example. Along with the broke file comes the render output and the render output that i would have expect to show ghostframes/blury frames and the original file (4k from canon camera). [MVI_7312.MP4](https://archive.blender.org/developer/F13404640/MVI_7312.MP4) [lastSyncTest01.blend](https://archive.blender.org/developer/F13404639/lastSyncTest01.blend) [lastSyncTest01_rendering01_blury.mp4](https://archive.blender.org/developer/F13404588/lastSyncTest01_rendering01_blury.mp4) [lastSyncTest01_rendering01.mp4](https://archive.blender.org/developer/F13404589/lastSyncTest01_rendering01.mp4)

Michael commented

2022-08-19 15:02:40 +02:00

Can you upload the original project file? I would like to reproduce this issue and fix encoder settings if this still happens. I need the file, because it should contain blender version it was last saved with, unless you re-saved file in newer one.

these are two blendfiles i used to render the EasyRobot_Final.mp4 file. two because sometimes i save a new version after render. VideoSchnittTemplate24.blend

VideoSchnittTemplate25.blend
the power sequencer setting to render chunks is nothing I am aware of. If its a default i might have used it.

> Can you upload the original project file? I would like to reproduce this issue and fix encoder settings if this still happens. I need the file, because it should contain blender version it was last saved with, unless you re-saved file in newer one. these are two blendfiles i used to render the EasyRobot_Final.mp4 file. two because sometimes i save a new version after render. [VideoSchnittTemplate24.blend](https://archive.blender.org/developer/F13404928/VideoSchnittTemplate24.blend) [VideoSchnittTemplate25.blend](https://archive.blender.org/developer/F13404929/VideoSchnittTemplate25.blend) the power sequencer setting to render chunks is nothing I am aware of. If its a default i might have used it.

Richard Antalik commented

2022-08-22 11:48:01 +02:00

Thanks for files.
Since it was saved with version 2.82, I have tried to render sample by adding own material to timeline. However even if I render with version 2.82, I get very different metadata:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '0000-0100.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    date            : 2022/08/22 11:16:01
    encoder         : Lavf58.12.100
  Duration: 00:00:01.68, start: 0.000000, bitrate: 9333 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 9128 kb/s, 60 fps, 60 tbr, 90k tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 190 kb/s (default)
    Metadata:
      handler_name    : SoundHandler

Mainly encoder: Lavf58.12.100 is what I would expect here, since this is what we supplied Blender 2.82 with.
Looked into power sequencer and it does not implement multithreaded rendering - it is standalone script only so this is not a factor here.

So far it looks to me, that the provided video got corrupted somehow. Are you able to re-render the video with Blender 2.82? At least a portion of it?

In #100495#1406111, @Michael-47 wrote:
sorry if this is leading away from the orignal bug. i feel like it is related.

If the video is comming from different device/software It should be reported in new report. I will have a look at it, but it will likely be completely different cause of the seemingly same issue.

Also looking at file, it was saved with 3.2 version, but seeking improvements have been implemented in 3.3 version, so check with latest alpha - I was not able to reproduce any issues.

Thanks for files. Since it was saved with version 2.82, I have tried to render sample by adding own material to timeline. However even if I render with version 2.82, I get very different metadata: ``` Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '0000-0100.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 date : 2022/08/22 11:16:01 encoder : Lavf58.12.100 Duration: 00:00:01.68, start: 0.000000, bitrate: 9333 kb/s Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 9128 kb/s, 60 fps, 60 tbr, 90k tbn, 120 tbc (default) Metadata: handler_name : VideoHandler Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 190 kb/s (default) Metadata: handler_name : SoundHandler ``` Mainly `encoder: Lavf58.12.100` is what I would expect here, since this is what we supplied Blender 2.82 with. Looked into power sequencer and it does not implement multithreaded rendering - it is standalone script only so this is not a factor here. So far it looks to me, that the provided video got corrupted somehow. Are you able to re-render the video with Blender 2.82? At least a portion of it? ----- > In #100495#1406111, @Michael-47 wrote: > sorry if this is leading away from the orignal bug. i feel like it is related. If the video is comming from different device/software It should be reported in new report. I will have a look at it, but it will likely be completely different cause of the seemingly same issue. Also looking at file, it was saved with 3.2 version, but seeking improvements have been implemented in 3.3 version, so check with latest alpha - I was not able to reproduce any issues.

Michael commented

2022-08-22 14:13:45 +02:00

So far it looks to me, that the provided video got corrupted somehow. Are you able to re-render the video with Blender 2.82? At least a portion of it?

The video file I uploaded was somewhat chosen by random. I just tried another file from 3 month later and one from 6 month before (not sure with blender version was used but i use most recent usually). They all have issues in 3.2. Current alpha is much better but i still felt like the preview glitches after a few split cuts. And after a refresh I also found cuts being off by a frame or two. Regarding this information what should do next? Regarding your question: I think I could rerender the file from the bugreport but as mentioned I do not feel its just this file.

If the video is comming from different device/software It should be reported in new report. I will have a look at it, but it will likely be completely different cause of the seemingly same issue.
Also looking at file, it was saved with 3.2 version, but seeking improvements have been implemented in 3.3 version, so check with latest alpha - I was not able to reproduce any issues.

I reproduced this with current alpha. The .blend is attached. Use MVI_7312.mp4 to reproduce. I still think it is the same problem (preview glitching when seeking/scrubbing) and just another way to visualize it. This method is better to see slight glitches.

Alpha_CameraMP4Test.blend

> So far it looks to me, that the provided video got corrupted somehow. Are you able to re-render the video with Blender 2.82? At least a portion of it? The video file I uploaded was somewhat chosen by random. I just tried another file from 3 month later and one from 6 month before (not sure with blender version was used but i use most recent usually). They all have issues in 3.2. Current alpha is much better but i still felt like the preview glitches after a few split cuts. And after a refresh I also found cuts being off by a frame or two. Regarding this information what should do next? Regarding your question: I think I could rerender the file from the bugreport but as mentioned I do not feel its just this file. > If the video is comming from different device/software It should be reported in new report. I will have a look at it, but it will likely be completely different cause of the seemingly same issue. > Also looking at file, it was saved with 3.2 version, but seeking improvements have been implemented in 3.3 version, so check with latest alpha - I was not able to reproduce any issues. I reproduced this with current alpha. The .blend is attached. Use MVI_7312.mp4 to reproduce. I still think it is the same problem (preview glitching when seeking/scrubbing) and just another way to visualize it. This method is better to see slight glitches. [Alpha_CameraMP4Test.blend](https://archive.blender.org/developer/F13411094/Alpha_CameraMP4Test.blend)

Richard Antalik commented

2022-08-22 17:40:35 +02:00

In #100495#1407031, @Michael-47 wrote:

So far it looks to me, that the provided video got corrupted somehow. Are you able to re-render the video with Blender 2.82? At least a portion of it?

The video file I uploaded was somewhat chosen by random. I just tried another file from 3 month later and one from 6 month before (not sure with blender version was used but i use most recent usually). They all have issues in 3.2. Current alpha is much better but i still felt like the preview glitches after a few split cuts. And after a refresh I also found cuts being off by a frame or two. Regarding this information what should do next? Regarding your question: I think I could rerender the file from the bugreport but as mentioned I do not feel its just this file.

My current understanding of this problem is, that file you have provided is broken, and I am 90% confident, it has either not been rendered with Blender or has been re-encoded at some point. I don't have any reason to not believe you, that it has been rendered by Blender though, which is why I want you to try to render it again and see if new file would behave normally (I am quite confident it would). If it won't help, I would probably want to see smaller chunk (250 frames or so) of render, to examine it's metadata. Then if I would see same metadata as in original file I would probably request Blender binary you have used and summon other developers to explain to me how it is possible that it uses encoder we do not supply in official distributions.

If you are willing to re-render the video, you can download previous versions of Blender here: https://download.blender.org/release/Blender2.82/

If the video is comming from different device/software It should be reported in new report. I will have a look at it, but it will likely be completely different cause of the seemingly same issue.
Also looking at file, it was saved with 3.2 version, but seeking improvements have been implemented in 3.3 version, so check with latest alpha - I was not able to reproduce any issues.

I reproduced this with current alpha. The .blend is attached. Use MVI_7312.mp4 to reproduce. I still think it is the same problem (preview glitching when seeking/scrubbing) and just another way to visualize it. This method is better to see slight glitches.

Alpha_CameraMP4Test.blend

We have implemenmted a fair bit of workarounds for seeking issues which unfortunately come in many forms. You would see that frame is off and refresh mostly works, but this is mostly true for all sorts of causes.

In any case I don't have file Alpha_CameraMP4Test.mp4, I assume I have to render it from file MVI_7312.MP4, is that correct? I did that and did not see any problem.

Better way to check for errors is color mix effect strip with difference mode and then multiply colors to better see tiny details

So if original strip and render are aligned here is difference:
no_offset.mp4
Without colors being multiplied, you would see almost nothing, and what you see is pretty much loss of quality due to encoder optimizing the image. Perceptually lossless is not quite lossless.

Here I intentionally misaligned strips so there is 1-frame offset:
1_frame_offset.mp4
It would be quite obvious if any frame is misalligned

also here is my .blend file for reference:
#100495.blend

> In #100495#1407031, @Michael-47 wrote: > >> So far it looks to me, that the provided video got corrupted somehow. Are you able to re-render the video with Blender 2.82? At least a portion of it? > The video file I uploaded was somewhat chosen by random. I just tried another file from 3 month later and one from 6 month before (not sure with blender version was used but i use most recent usually). They all have issues in 3.2. Current alpha is much better but i still felt like the preview glitches after a few split cuts. And after a refresh I also found cuts being off by a frame or two. Regarding this information what should do next? Regarding your question: I think I could rerender the file from the bugreport but as mentioned I do not feel its just this file. My current understanding of this problem is, that file you have provided is broken, and I am 90% confident, it has either not been rendered with Blender or has been re-encoded at some point. I don't have any reason to not believe you, that it has been rendered by Blender though, which is why I want you to try to render it again and see if new file would behave normally (I am quite confident it would). If it won't help, I would probably want to see smaller chunk (250 frames or so) of render, to examine it's metadata. Then if I would see same metadata as in original file I would probably request Blender binary you have used and summon other developers to explain to me how it is possible that it uses encoder we do not supply in official distributions. If you are willing to re-render the video, you can download previous versions of Blender here: https://download.blender.org/release/Blender2.82/ ---- > >> If the video is comming from different device/software It should be reported in new report. I will have a look at it, but it will likely be completely different cause of the seemingly same issue. >> Also looking at file, it was saved with 3.2 version, but seeking improvements have been implemented in 3.3 version, so check with latest alpha - I was not able to reproduce any issues. > I reproduced this with current alpha. The .blend is attached. Use MVI_7312.mp4 to reproduce. I still think it is the same problem (preview glitching when seeking/scrubbing) and just another way to visualize it. This method is better to see slight glitches. > > [Alpha_CameraMP4Test.blend](https://archive.blender.org/developer/F13411094/Alpha_CameraMP4Test.blend) We have implemenmted a fair bit of workarounds for seeking issues which unfortunately come in many forms. You would see that frame is off and refresh mostly works, but this is mostly true for all sorts of causes. In any case I don't have file `Alpha_CameraMP4Test.mp4`, I assume I have to render it from file `MVI_7312.MP4`, is that correct? I did that and did not see any problem. Better way to check for errors is color mix effect strip with difference mode and then multiply colors to better see tiny details So if original strip and render are aligned here is difference: [no_offset.mp4](https://archive.blender.org/developer/F13411441/no_offset.mp4) Without colors being multiplied, you would see almost nothing, and what you see is pretty much loss of quality due to encoder optimizing the image. Perceptually lossless is not quite lossless. Here I intentionally misaligned strips so there is 1-frame offset: [1_frame_offset.mp4](https://archive.blender.org/developer/F13411446/1_frame_offset.mp4) It would be quite obvious if any frame is misalligned also here is my .blend file for reference: [#100495.blend](https://archive.blender.org/developer/F13411470/T100495.blend)

Michael commented

2022-08-22 19:23:54 +02:00

My current understanding of this problem is, that file you have provided is broken, and I am 90% confident, it has either not been rendered with Blender or has been re-encoded at some point.

When looking into the working files I saw that for this specific project I used blender to render the picture and audio separately. Making some post production to the audio and then putting picture and audio together using VLC Mediaplayer. I did this only for this one project and forgot about it. I am Sorry! (If you want I still can upload the rerender)

> My current understanding of this problem is, that file you have provided is broken, and I am 90% confident, it has either not been rendered with Blender or has been re-encoded at some point. When looking into the working files I saw that for this specific project I used blender to render the picture and audio separately. Making some post production to the audio and then putting picture and audio together using VLC Mediaplayer. I did this only for this one project and forgot about it. I am Sorry! (If you want I still can upload the rerender)

Michael commented

2022-08-22 19:38:34 +02:00

We have implemenmted a fair bit of workarounds for seeking issues which unfortunately come in many forms. You would see that frame is off and refresh mostly works, but this is mostly true for all sorts of causes.

In any case I don't have file Alpha_CameraMP4Test.mp4, I assume I have to render it from file MVI_7312.MP4, is that correct? I did that and did not see any problem.

Better way to check for errors is color mix effect strip with difference mode and then multiply colors to better see tiny details

So if original strip and render are aligned here is difference:
no_offset.mp4
Without colors being multiplied, you would see almost nothing, and what you see is pretty much loss of quality due to encoder optimizing the image. Perceptually lossless is not quite lossless.

Here I intentionally misaligned strips so there is 1-frame offset:
1_frame_offset.mp4
It would be quite obvious if any frame is misalligned

also here is my .blend file for reference:
#100495.blend

Thanks for investigating. Looking at your video files leaves me asking if this is a render output? I have problems with the preview. I use this overlaying method to find frames where the preview of the edited original (buttom layer) is different to the upper layer (render result). If I find one I refresh and see if it helps, often it doesn't. Rendering the composition of the two layers as video however does not show a difference, which suggests to me that the preview is off. Here is a screenshot of the preview + render result (right after refreshing, using currrent alpha version)

Sorry for forgetting to upload the neccesairy files. Here they are: Alpha_CameraMP4Test_blury.mp4 Alpha_CameraMP4Test.mp4

> We have implemenmted a fair bit of workarounds for seeking issues which unfortunately come in many forms. You would see that frame is off and refresh mostly works, but this is mostly true for all sorts of causes. > > In any case I don't have file `Alpha_CameraMP4Test.mp4`, I assume I have to render it from file `MVI_7312.MP4`, is that correct? I did that and did not see any problem. > > Better way to check for errors is color mix effect strip with difference mode and then multiply colors to better see tiny details > > So if original strip and render are aligned here is difference: > [no_offset.mp4](https://archive.blender.org/developer/F13411441/no_offset.mp4) > Without colors being multiplied, you would see almost nothing, and what you see is pretty much loss of quality due to encoder optimizing the image. Perceptually lossless is not quite lossless. > > > Here I intentionally misaligned strips so there is 1-frame offset: > [1_frame_offset.mp4](https://archive.blender.org/developer/F13411446/1_frame_offset.mp4) > It would be quite obvious if any frame is misalligned > > also here is my .blend file for reference: > [#100495.blend](https://archive.blender.org/developer/F13411470/T100495.blend) Thanks for investigating. Looking at your video files leaves me asking if this is a render output? I have problems with the preview. I use this overlaying method to find frames where the preview of the edited original (buttom layer) is different to the upper layer (render result). If I find one I refresh and see if it helps, often it doesn't. Rendering the composition of the two layers as video however does not show a difference, which suggests to me that the preview is off. Here is a screenshot of the preview + render result (right after refreshing, using currrent alpha version) ![image.png](https://archive.blender.org/developer/F13411656/image.png) Sorry for forgetting to upload the neccesairy files. Here they are: [Alpha_CameraMP4Test_blury.mp4](https://archive.blender.org/developer/F13411628/Alpha_CameraMP4Test_blury.mp4) [Alpha_CameraMP4Test.mp4](https://archive.blender.org/developer/F13411627/Alpha_CameraMP4Test.mp4)

Richard Antalik commented

2022-08-22 19:46:44 +02:00

In #100495#1407178, @Michael-47 wrote:

My current understanding of this problem is, that file you have provided is broken, and I am 90% confident, it has either not been rendered with Blender or has been re-encoded at some point.

When looking into the working files I saw that for this specific project I used blender to render the picture and audio separately. Making some post production to the audio and then putting picture and audio together using VLC Mediaplayer. I did this only for this one project and forgot about it. I am Sorry! (If you want I still can upload the rerender)

Thanks for info. In this case you can report a bug to VLC if it's still reproducible. You said, that you have other broken files so I can have a look at them, but best would be to create new report for that. For example the file from your camera I would need to clarify steps to reproduce, because I can't replicate any issue there.

Just a tip: when Blender fails to seek to exact timestamp, it emits a red log line where it says something like "scan unhappy". To see it you have to run Blender with --debug-ffmpeg argument. The logs are quite noisy, but the red line usually pops up and it is easy to spot.

So if you can include a log like this

[mov,mp4,m4a,3gp,3g2,mj2 @ 00000193b5c43640]   FRAME DONE: cur_pts=85738, guessed_pts=85738
[h264 @ 00000193d14fea80] nal_unit_type: 9(AUD), nal_ref_idc: 0
[h264 @ 00000193d14fea80] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 3
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000193b5c43640] DECODE UNHAPPY: PTS not matched!

I would know where to look for bad frames (cur_pts=85738 tells me the position)

> In #100495#1407178, @Michael-47 wrote: >> My current understanding of this problem is, that file you have provided is broken, and I am 90% confident, it has either not been rendered with Blender or has been re-encoded at some point. > When looking into the working files I saw that for this specific project I used blender to render the picture and audio separately. Making some post production to the audio and then putting picture and audio together using VLC Mediaplayer. I did this only for this one project and forgot about it. I am Sorry! (If you want I still can upload the rerender) Thanks for info. In this case you can report a bug to VLC if it's still reproducible. You said, that you have other broken files so I can have a look at them, but best would be to create new report for that. For example the file from your camera I would need to clarify steps to reproduce, because I can't replicate any issue there. Just a tip: when Blender fails to seek to exact timestamp, it emits a red log line where it says something like "scan unhappy". To see it you have to run Blender with `--debug-ffmpeg` argument. The logs are quite noisy, but the red line usually pops up and it is easy to spot. So if you can include a log like this ``` [mov,mp4,m4a,3gp,3g2,mj2 @ 00000193b5c43640] FRAME DONE: cur_pts=85738, guessed_pts=85738 [h264 @ 00000193d14fea80] nal_unit_type: 9(AUD), nal_ref_idc: 0 [h264 @ 00000193d14fea80] nal_unit_type: 1(Coded slice of a non-IDR picture), nal_ref_idc: 3 [mov,mp4,m4a,3gp,3g2,mj2 @ 00000193b5c43640] DECODE UNHAPPY: PTS not matched! ``` I would know where to look for bad frames (`cur_pts=85738` tells me the position)

Michael commented

2022-08-22 19:54:19 +02:00

Ok, taking a step back from this. I reported a bug because I had problems with glitches in the Preview with different files. I chose a file that was most problematic/easy to reproduce. It turned out to be broken or at least not straight from blender. But I experience problems with other files, too. Its better in the alpha (when refreshing often). Now I do not know, should I investigate more into other video files or is it a known issue that the preview is not perfect?

Michael commented

2022-08-28 11:41:36 +02:00

Thanks for investigating. Looking at your video files leaves me asking if this is a render output? I have problems with the preview. I use this overlaying method to find frames where the preview of the edited original (buttom layer) is different to the upper layer (render result). If I find one I refresh and see if it helps, often it doesn't. Rendering the composition of the two layers as video however does not show a difference, which suggests to me that the preview is off. Here is a screenshot of the preview + render result (right after refreshing, using currrent alpha version)

I just file another bug report #100672. I did not include the file from the camera because it is 2gb and re-uploading it takes forever. In the quoted comment above I tried to further explain what I experience (preview glitsches, not differences in rendered result). Maybe you want to look at it again.

> Thanks for investigating. Looking at your video files leaves me asking if this is a render output? I have problems with the preview. I use this overlaying method to find frames where the preview of the edited original (buttom layer) is different to the upper layer (render result). If I find one I refresh and see if it helps, often it doesn't. Rendering the composition of the two layers as video however does not show a difference, which suggests to me that the preview is off. Here is a screenshot of the preview + render result (right after refreshing, using currrent alpha version) I just file another bug report #100672. I did not include the file from the camera because it is 2gb and re-uploading it takes forever. In the quoted comment above I tried to further explain what I experience (preview glitsches, not differences in rendered result). Maybe you want to look at it again.

Richard Antalik commented

2022-08-29 11:10:23 +02:00

Changed status from 'Confirmed' to: 'Archived'

Richard Antalik closed this issue

2022-08-29 11:10:23 +02:00

Richard Antalik commented

2022-08-29 11:10:23 +02:00

Sorry for delay, and thanks for new report, will check it out. This one I will close since other media players have trouble processing it too.

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BlenderVSE: Seeking/Scrubbing issue #100495