@emmrecs

Hi Jeff

Try this link

@AAProds

Hi Al

I have fixed the link in your comment - there was a missing l from html in this section of the URL

net/avidemux.html#xl_HeadingAnchor

John EB

@johnebaker @emmrecs

Arrgh. I had a combination of htms and htmls on my site so I thought I'd standardise, not realising that all my old links would be blown up. Sorry about that.

If one doesn't work, try the other! 😂😂

@emmrecs @johnebaker

Change of plan, I'm back to "htm" files until I think the "html" change through more thoroughly. So Jeff, for the foreseeable future, use:

https://www.aaproductions.net/avidemux.htm#xl_HeadingAnchor:589YYny

@AAProds @johnebaker

Hi Al, Hi John,

Sorry for the delay in creating the requested snippet but it can now be downloaded from https://we.tl/t-AkN9kkKndc

This is taken from a "new" transfer to computer from the source VHS tape, using my Canopus ACEDVio Capture Card. The resulting file is DV AVI.

Bizarrely, the AviDemux snippet clearly shows the picture tearing-and ghosting that plagues this video but playback of the file in VPX/MMS does NOT, even at full screen. Why?? If this problem had affected all the recent transfers from VHS that I've done, I would at least begin to suspect the Magix Capture app but it is only this tape.

Thankfully the client for whom this work is being undertaken is being very patient but I really would like to get to the bottom of this, if possible!

Jeff

@emmrecs

Hi Jeff.

I think my copy of VPX is dropping frames at normal speed playback. Try reducing the speed of the clip to 12.25 frames per second. Also right clicking the file and looking at properties I have never seen a third section of shooting data before. I'm intrigued.

Ray.

@emmrecs

Hi Jeff

. . . . snippet clearly shows the picture tearing-and ghosting that plagues this video but playback of the file in VPX/MMS does NOT, even at full screen . . . .

Same here it is bad.

. . . . Why?? If this problem had affected all the recent transfers from VHS that I've done . . . .

See the 3rd post here, counting Google ad as no 2, is very detailed analysis.

VPX export tested:

• 3 different progressive formats including AVI, all play OK - I think the deintelacing is fixing the issue.
   
• 2 different interlaced formats MPEG2 (BFF) + AVCHD (TFF) show the tearing / combing.

HTH

John EB

@johnebaker

So the conclusion is that tape was recorded on a different machine?

Ray.

@CubeAce, @emmrecs

Hi Ray, Jeff

. . . . the conclusion is that tape was recorded on a different machine . . . .

It may have however there are other possibilities eg if the tape is in a poorer condition than the other 3, there may be adhesion between the layers causing momentary sticking, sometimes called stiction, which causes the timebase error described in the 1st paragraph of the quote in 3rd comment.

John EB

@johnebaker

Hi John.

I suppose there are lots of possibilities but I'm sure @emmrecs is experienced enough to ffw/rw a tape before attempting to play it after storage. Another possibility is tape thickness. A long play tape as opposed to a standard play tape. I'm not convinced that VHS tapes always go back into shape after being stretched. One reason open reel tape later got the choice of being matt backed was to help prevent such deformation. Did you try slowing the playback to half speed? All those problems show up that don't playing back at normal speed. So what is being binned in VPX/MMS during normal playback?

Ray.

@emmrecs

Eeek. Looking at it in VDub and discarding the fields, the problem is with the top fields. Some are "kept", way after the scene moves on. A good example is when the fellow on the right passes the structure walking slowly towards the other fellow. One of the top fields gets stuck for a few frames. Here's a screen cap showing the issue. Here, I'm tapping through the video manually; watch the frame number advance and note how many frames the field sticks for.

Magix does indeed seem to play it OK, but when you drag the play marker through it, the jerkiness (field hang) can be seen. H264 export is fine, but MPEG 2 is borked because it is interlaced and jerks because of the top field problem.

What to do about it?

Are you running the video through some sort of stabiliser (TBC or specific DVD recorder) before the digitiser? That might smooth out the field stream.

Run another capture of the same area and compare: that will isolate the issue to the tape (or a quirk in your capture card).

Do an analogue capture with your Magix dongle, either using the Magix analogue capture feature or AmarecTV

If your final format is DVD, then if all else fails, deinterlace it in VDub, discarding the top field, save as an AVI and import that into Magix and burn. Handbrake can also deinterlace but it seems as though you can't pick a particular field to discard. You might have to experiment with that.

Here's an AVI with the top field discarded. Still looks OK and exports to MPEG 2 correctly.

https://drive.google.com/file/d/1PPGXRTgYk3MjLt8dCXknJDgYT-3-QHB1/view?usp=sharing

@emmrecs

Re the Magix smoothness, it must be discarding or merging the fields somehow. If you set 50fps in the move settings, Magix will, in effect, put each field in it's own frame and you can see the field error, with the video jumping about as each field is displayed.

Now I remember. 😂 If you have a 25fps timeline and insert a 25fps interlaced file (ie 50 fields per second) and then, in the Video object properties choose bottom field first or top field first, that's all you'll get, not the other field. If you choose full frame, you'll get both fields together.

So, in Jeff's case, because the dodgy field is the top field, and DV is bottom field first, on import, you'll only see the (good) bottom fields, never the top fields.

If you're interested, have a play with this file (a Lagarith AVI with numbered fields):

https://drive.google.com/file/d/106wF-XGbjVHb_F_Vb5IB2b7Lt-wCf0RR/view?usp=sharing

@AAProds

Hi Al,

Thanks again for all your help!

Do an analogue capture with your Magix dongle, either using the Magix analogue capture feature

The first capture, the one that lead to creating this thread (and with the earlier examples attached), was with the Magix dongle; this latest is yet another attempt to find a solution, now with the Canopus card.

Re the TBC; I created both captures with an external TBC, an AVT-8170, in circuit. Based on the article that @johnebaker linked yesterday I'm minded to try something wholly counter-intuitive and bypass it! It might be worth at least a try!

I will also try the deinterlace suggestion in VDub.

Jeff

@emmrecs

I'm minded to try something wholly counter-intuitive and bypass it! It might be worth at least a try!

Yes, absolutely.

At least you're homing in on the issue; it can now only be the tape, the VCR or the 8710.

@AAProds @johnebaker

I think I'm beginning to get somewhere!

The Deinterlace in VDub did not work to any great extent, but removing the TBC from the input chain did! I now have a capture whose export and burn to DVD is not plagued by ghosting and duplicated frames.

Now, I have to determine whether the TBC is "faulty" (the other 4 tapes for this client were all digitised using it, without problem) or whether there is something very strange about this particular tape.

Thank to all who contributed ideas; your support/advice is very much appreciated, @AAProds @johnebaker @CubeAce @ericlnz

Jeff

Hi Jeff

. . . . I have to determine whether the TBC is "faulty" . . . . .

Does the VHS player have TBC and is it turned on or off / set to pass through.

@AAProds

Hi Al

If TBC is applied twice, once in the player and again in a TBC correction device is there a conflict?

John EB

@johnebaker

Hi John,

No, no TBC in the player.

Jeff

@johnebaker

John, not a whizz on TBCs; however my understanding is that you switch off the VCR's internal line TBC fi you're using an external stabiliser such as a DVD recorder. As for proper TBCs like Jeff's, or the TBC-1000, I don't know. I am not in the exalted TBC-owner's club. I chug along with a Panny DVD recorder.