Broken lines when capturing via pc

[Galif]

Hi to everyone!

First of all sorry for my english!
In the picture, on the left, is a magnified screenshot of video which was captured to dvd whereas on the right side of the photo is the outcome when I captured the same vhs tape via pc (the hardware consists of vhs player jvc hr-dvs2, blackmagic mini converter analog to sdi and an internal blackmagic video card). I cannot understand why there are these broken (only horizontal!!) lines when the vhs is captured via pc and blackmagic internal card.
It seems an interlaced problem;
[Attachment 71531 - Click to enlarge]

[jagabo]

https://www.videohelp.com/glossary?I#Interlace,%20Interlaced,%20Interlacing,%20non-progressive

It's not a problem. It's the nature of analog video. Note that your player/editor is automatically deinterlacing the DVD video. It's hard to tell from your image whether it's still interlaced or was poorly deinterlaced. Upload a short video sample.

[Bwaak]

Seems that only one field is used for the deinterlaced video instead of two, and deinterlacing itself is a simple line doubling.

It's not a problem. It's the nature of analog video.

Well, it is a hack invented in the 1930s, which has been a nuisance ever since.

[Galif]

Thank you for your reply jagabo.
I uploaded a short video, showing the two different ways of capturing the same vhs videotape.Compare Capturing via DVD or PC.mp4

[jagabo]

The problem is poor deinterlacing. But you should upload an original capture, not a processed video so I can tell if the problem is in the cap or your processing.

[Galif]

The software I used to capture the videotape is OBS and I also upload the settings I have set to OBS when capturing.
I cut the video through davinci resolve because it is too big to upload but I export (MediaInfo program) the settings that original capture file has.
[ATTACH]OBS Settings_Original capture file settings.7z[/ATTACH]

Moreover, the deinterlacing method was Yadif 2X Top Field First.

[jagabo]

I believe OBS is your problem. The video has already been deinterlaced and encoded progressive. It should have been left interlaced and encoded interlaced. Best practice is to use traditional video capture software and capture 25 fps 720x576 interlaced YUV 4:2:2 (YUY2, YUYV, etc.) and compresses with a fast lossless codec. Then later encode with a high compression codec like x264 and encode 25 fps interlaced. Or use a high quality deinterlacer like AviSynth's QTGMC and encoded 50 fps progressive. See the attached videos of what to expect.

https://web.archive.org/web/20051215123131/http://www.fourcc.org/

I don't know what capture device you're using but try capturing with VirtualDub or AmarecTV.

[Galif]

Thank you very much. I think you have right!
I made some tests and one of them is to capture with obs with deinterlacing method disabled. The capture has broken lines (interlaced) and is awful but I deinterlaced it afterwords. I render it with davinci resolve and deinterlace it with davinci feature. The video became just perfect! Much better than capturing with deinterlaced method checked (Yadif 2X Top Field First).

Thank you again!!! You were very helpful.

[jagabo]

Find some colorful video with significant motion and verify that the chroma isn't blended. That's a very common problem with improper handling of interlaced video.

[lordsmurf]

FYI, OBS is not suggest for capture software.
Lots of loss, odds errors (since not actually analog capturing software).

You have a great VCR there, the DVS2, so don't reverse quality by using the wrong software. Use VirtualDub.

[Alwyn]

I made some tests and one of them is to capture with obs with deinterlacing method disabled. The capture has broken lines (interlaced) and is awful but I deinterlaced it afterwords.

Don't be worried by the jaggies after the capture. This is absolutely normal when you do an interlaced capture. You have to use another program/process to deinterlace it (as you have done with Resolve).

[Galif]

I had tried VirtualDub in the past, but it can capture only huge avi files. Am I wrong;

[Alwyn]

I had tried VirtualDub in the past, but it can capture only huge avi files. Am I wrong;

Depends on the definition of "huge". If you capture with Virtual Dub using no codec, then yes, the files are huge (>100gb per hour). But what is recommended is to capture with the Lagarith or HUFFYUV codecs. This results in compressed but lossless files of around 30-40gb per hour. You would have to check Resolve can import Lagarith or HUFFYUV AVIs.

[Galif]

Thanks Alwyn. I will try to.

[Alwyn]

Once you've installed the codecs, open Virtual Dub, get into Capture mode, then on the Video menu, right down the bottom, Compression, and choose one of them.

[Galif]

Dear Alwyn. I tried to capture via virtualdub with lagarith codec but the captured file is in slow motion and with no sound (only noise). I tried to alter the parameters but I am still confused about what is going wrong. Am i virtual du(m)b;
Basket VirtualDubLagarithNEW5.avi

[jagabo]

The timestamps are all messed up. If one ignores the video timestamps and assumes 25 fps the video plays smoothly. Audio problems in VirtualDub often manifest as video timing issues. Try capturing (not converting) the audio as 16 bit integer, not 32 bit floats.

LWLibavVideoSource("Basket VirtualDubLagarithNEW5.avi", cache=false, prefer_hw=2) 
AssumeTFF()
QTGMC()
Crop(6,0,-10,-0)

[Alwyn]

Players on a go-slow for more pay?

You've got the LAGS video codec working. Good job!

In VDub, when you're in Capture mode and your digitiser is plugged in and ready to go, on the Audio menu, choose "0 Capture device".

Other than that, there is another setting, depending on what version you have. The preferred VDub for capturing is v1.9.11. There's a copy here.

If you keep having trouble with VDub, we're moving to AmarecTV for capture. VDub can be a nightmare and there are no quick-start guides for it. AmarecTV is a "flat" program, with a few simple screens and is easy to set up.

On your captured video, you'll notice the interlacing (your "broken lines"). We'll get rid of that with a filter (ironically, with VDub!! ) after you get a good capture. It might not be quite as good as Jagabo's excellent effort, but we'll try.

[Galif]

Thank you Sagabo!

I did it!!! The sound is perfect (RAW AUDIO FORMAT: PCM 48000Hz, stereo, 16-bit) and I changed the video format from "AUTO" to "625p50PAL-8 bit YUV".

Thank you again for your help.
Basket VirtualDubLagarithNEW6.avi

[Galif]

Hello Alwyn!

Thank for the info.
I had in mind to deinterlaced via AviSynth (yes, I think it's really a nightmare this script-program) but I could try your idea with VDub.

[Alwyn]

Glad you're underway.

I could try your idea with VDub.

Try the Deinterlace filter, set to YADIF, double frame rate, Top field first. It's not quite as good as QTGMC but...

[jagabo]

Thank you Sagabo!

I did it!!! The sound is perfect (RAW AUDIO FORMAT: PCM 48000Hz, stereo, 16-bit) and I changed the video format from "AUTO" to "625p50PAL-8 bit YUV".

Thank you again for your help.

[Attachment 71697 - Click to enlarge]

The new cap looks good. Video and audio.

[Galif]

Hello out there!
After testing your ideas I did 4 completely different captures with the same video and afterward I made one video to compare them.
The left two columns regards capture with OBS and the right two with VirtualDub. The deinterlaced method is different in every one of them and I think that capturing with VirtualDub and deinterlacing the video with QTGMC is the best method by far.

Thank you all for sharing your knowledge with me and helping me find the root of the problem.
Compare File.mp4

[jagabo]

I don't now why that video is 23.976 fps with bt.709 colors. QTGMC with a 25 fps source should give you 50 fps (much smoother motion). Standard definition video is normally bt.601 colors. But for comparing the four deinterlacing methods it's adequate. You can see that QTGMC gives you far fewer aliasing artifacts.

[Alwyn]

@Galif, There seems to be an excessive of interlace jaggies on the Virtual Dub capture/Yadif deint. Did you use Yadif Double Frame Rate, TFF?

[Galif]

The fps is my mistake while rendering in Davinci. I use to set 701 color space when capture VHS but you have right...it is useless because is sd.
I am not sure if I use the right setting when deinterlace via virtualdub. I upload a photo for sure.
[Attachment 71746 - Click to enlarge]

[Alwyn]

My understanding is Vdub Deinterlace would be better as Yadif, Double frame rate Top Field First.

[jagabo]

Yes, for smoothest motion you want to use Yadif and "double frame rate". Your video is top field first, so you pick "Double frame rate, top field first". If you pick the wrong field order you will get "two steps forward, one step back" type motion when you step through frames.