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Extreme pixel distortion in mp4


jfraze
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I'm suddenly noticing that quite a few of my mp4 files saved from VP have large regions of extreme pixel distortion. I'm not even sure how to describe it. Giant block-sized pixels, colors completely blown out or changed, enormous compression artifacts... the video is unrecognizable and unwatchable. (Is there a way to post a screen shot here?)

So far I haven't found it in any of the DVDs I've burned from the same projects, but I haven't watched them all through end to end. I normally make a backup mp4 file to my PC so it can be watched directly from the computer (on the assumption that one day DVDs, practical as they are for archiving video material, will be too denigrated to play anywhere). By accident I discovered this error on one video, and in checking a number of others found large regions with the same problem. It's oddly inconsistent... the video will play fine for a while then reach a messed up spot which can go on for minutes at a time. I've tried viewing the same video on different computers, and the ruined sections are in the same spot each time, and identical pixel-by-pixel, so clearly this is a problem with the saved file itself, not a playback issue. The problems did not appear in the original videos: only in the exported file out of the VP project.

Obviously this is a major concern. Most of my mp4 files turn out to be unwatchable, and I'm concerned I'll find this problem in my DVDs as well.

Why should I be getting such bad results from exporting to video file as opposed to burning directly to DVD? Is there a setting I need to be aware of? Should I just give up on "Export/Video File"? Use a format other than mp4? Could something be wrong with my workflow?

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What VP version produced these video files?  What export resolution was used?

To share a screen shot, upload the image to a free server, such as Google Drive or MS OneDrive, get a shared (public) link, copy the link and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum.  It will appear as a clickable link.  If using Google Drive, verify that "anyone with link can view" - not "restricted."

A sample PROJECT would be most helpful.  Share it and someone will take a look.  The process is easy, quick and can be done privately.  Just follow these steps...

  •     Back up --- With your project on the timeline, click on MENU at the top-left.  Click FILE|BACK UP PROJECT FILES TO FOLDER.  Choose a folder and SELECT FOLDER.
  •     Upload ---  Use a free server - Google Drive, MS OneDrive, etc.* - to upload the saved, numbered FOLDER.    Do NOT upload the individual VPJ or export file. 
  •     Get link --- Get a public link.  If using Google Drive click GET SHAREABLE LINK. If necessary change "restricted" to "anyone with the link can view" 
  •     Share ---     Click COPY LINK | DONE.  Paste that link here, or click the folder at the top-right of this forum to message it privately to me.  It won't be shared.

          *    Before uploading, right-click the folder, click PROPERTIES.  Look at the File Size to confirm that it's not too big for the free space on the server.

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It's set to auto-match resolution, but it hasn't anything to do with selected resolution: the video is fine on DVD, and fine through large portions of the project. Then it suddenly randomly goes bad for a while, and comes back, goes bad again, and so on. It would all be bad if I'd selected a low resolution. And this is WAY worse than a mere resolution issue.

If it helps, I was using default settings for export: Compressor was H264, Video Quality/Bitrate was set to Default, Lossless Export was set to Auto Detect. I can trying upping those settings, but I certainly can't imagine that this is the expected result of the default settings.

If this link works, this is what I'm ending up with for large stretches. And keep in mind the original video is fine, looks perfectly normal at 720 x 480. Only the exported files have these stretches of corruption.

https://drive.google.com/file/d/1RMQNIAJfuBDeIEJ-Pelvg0uuAP0cGGCE/view?usp=sharing

I'm attempting to let the computer run the export with no other applications running. Again, so far it has seemed that the DVD burns I've done are fine. This has apparently only happened on Export/Video File.

A lot of the original files have been deleted by now. All I have are the DVDs and the corrupted mp4 file. I don't suppose there's a fairly easy way to convert the DVD back into a mp4 video file?

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You didn't state the version used on that project.  What was the format of the source files? 

The distortion has been seen, rarely, in older VP versions.  It may be related to source file format.   For Lossless export settings, choosing RE-ENCODE instead of AUTO DETECT is worth a try.

Upgrade to the latest.  For licensed users upgrades are free for up to six months from purchase date.  After that, VP will continue to fully function but a fee will be required in order to register the newest.  Retain your old install file and registration info.

In lieu of missing source files - a project we can check out per the above instructions - use a DVD ripper to make an mp4.  A screen recorder should also work.

Check out these possibly related threads...

https://nch.invisionzone.com/topic/32559-video-artifactingblurring-on-import-of-file-and-remains-post-export/?tab=comments#comment-87578

https://nch.invisionzone.com/topic/35715-blurry-distored-and-pixelated-outputs/?tab=comments#comment-95323

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I just purchased it a little earlier this year so I'd assume it is the most recent version. It's v 9.09 (Mac). Source files were mp4 files captured with Debut. Again, the source files have been fine. I play them through (repeatedly) as I edit, add bookmarks, etc. and would absolutely NOT have missed distortion to this degree. The one or two that I still have source files for show no distortion at all in the sections that are ruined in the exported projects.

I could use Debut to capture the video from the DVD, but in that case I might as well go back to my original source tapes and start each project from scratch again. I'm hoping to avoid that, obviously. I'll check out HandBrake. That looks like it might save me some of that effort?

There's no artifacting or blurring on import, only on export. So the links don't apply to this issue.

I'm still mystified as to what has been causing this. I tried exporting one video with higher settings last night (instead of default) and that one came out OK. I'm doubtful that's the fix, though. If you saw the screen shot I'm sure you'd agree those are not the expected results from the default settings! Something went wrong, probably on my computer's end, I guess. I was hoping this might be a familiar problem that people had a ready fix for. I guess until I figure something out I'll just have to visually check my video files immediately after export, and attempt to re-do if they show corruption.

Thanks for looking into this. Hopefully HandBrake might save some work in restoring my already-bad files.

 

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Let's take a look at one or two of the files - so we can try to replicate what you see..  Please upload them to a free server, such as Google Drive or MS OneDrive, get a shared (public) link, copy the link and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum.

Using Google Drive, if necessary change "restricted" to "anyone with link can view."

The latest Mac release is 10.12.

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I don't think it would be practical to post the project file and all the original source files. Would it help just to post an effected section of an exported file, and the same section of the original file? I'm pretty sure the distortion happens randomly so I don't expect that if I export the same file via the same process that we'd end up with the same results each time.

Like I said, I was hoping it might be a familiar issue with a known solution. I don't know if it will be much use to put you through any further effort on trouble-shooting this. Thanks for the offer. Is it worth posting the samples?

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I uploaded a folder to Google Drive. I included the processed file just for comparison, so you can see when and where the distortion begins and ends in this particular clip. (Right in the middle of the clip, no transitions or scene changes.) That may be useful information.

I have my doubts the process is replicatable. If I re-do it now, just from this clip, it comes out differently. I suspect something is happening on my computer locally. As I'd said, I posted the question in the hopes that others have had similar issues, and maybe they might know what caused it, and know how they fixed it. If you can't replicate it on your system I think I'm out of luck. Thanks again for trying. If it doesn't work, c'est la guerre.

https://drive.google.com/drive/folders/1bG-kvp0Yhr_uREF8-Bc5Yj7_6wKJqjVF?usp=sharing

 

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Hi jfraze. I tried the uploaded original video in the latest v9.09 Mac release and the resulting mp4 files were good. Tried multiple times with lossless mode enabled and disabled. Does it only happen in mp4 format? How about using mov, flv, or avi? Please also try using H265 format in mp4 or mov format.

What is the macOS version and model of your Mac? What is its GPU?

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3 hours ago, borate said:

Thanks for sharing.  After those experiments you might enjoy this.

 Thanks for the effort.

Just FYI at this point, HandBrake works, but it takes longer to convert the DVD than just to re-record from the tapes, or re-record from the edited DVD. Then it changes a 2.5 GB file into a 16 GB file in the process, so I then need to import it into VP and spend another hour and a half re-exporting from VP to get the file size back down to something reasonable. I'm probably better off just re-capturing. At least if I did a lot of editing I have the DVD to capture from (Maybe there's a way to get a smaller file from HandBrake without losing quality that I don't know about.)

Nice video clip, thanks for sharing🙂. My samples were of my wife and I (and others) dancing with Erik Robeson and Sylvia Skylar back in the day. Back in the '90s-'00s they were sort of superstars of the swing revival. And nice people.

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13 minutes ago, macfly said:

Hi jfraze. I tried the uploaded original video in the latest v9.09 Mac release and the resulting mp4 files were good. Tried multiple times with lossless mode enabled and disabled. Does it only happen in mp4 format? How about using mov, flv, or avi? Please also try using H265 format in mp4 or mov format.

What is the macOS version and model of your Mac? What is its GPU?

Mac Mini running Mojave. 16 GB RAM, 2.3 GHz processor. I'm not sure what a GPU is but I'm guessing that's the video card: Intel HD Graphics 4000 1536 MB.

It's not the most powerful machine in the world, but it handles these files better than my 2-month old Windows machine. And please note it has shown no problems burning DVDs, just exporting to video file.

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16 minutes ago, jfraze said:

Mac Mini running Mojave. 16 GB RAM, 2.3 GHz processor. I'm not sure what a GPU is but I'm guessing that's the video card: Intel HD Graphics 4000 1536 MB.

It's not the most powerful machine in the world, but it handles these files better than my 2-month old Windows machine. And please note it has shown no problems burning DVDs, just exporting to video file.

Thanks. My Macbook also runs Mojave although its GPU is Intel Iris Pro. Please also try setting the frame rate to Constant 30 and in the mp4 encoding settings check Maximum key frame interval and set to 30. 

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40 minutes ago, macfly said:

Thanks. My Macbook also runs Mojave although its GPU is Intel Iris Pro. Please also try setting the frame rate to Constant 30 and in the mp4 encoding settings check Maximum key frame interval and set to 30. 

Thanks, I'll give that a try.

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1 hour ago, borate said:

Considering the archival VHS quality, a Debut capture might be the quickest route.

Yeah, some of the videos are in better shape than others, but they're all pretty old by now.

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