Capturing from VHS - dropped/repeated fields - how to fix?

[bergqvistjl]

I'm capturing from a VHS tape using VirtualDub with the following configuration

• Player: Panasonic NV-HS860 (Built-in TBC switched on, 3D DNR turned off) via S-VIDEO
• Card: Magewell Pro Capture HDMI

I'm saving this as an uncompressed AVI file, then running it through an avisynth script like so:

SetFilterMTMode("QTGMC", 2)
FFmpegSource2("Test.avi", atrack=1)
AssumeTFF()
QTGMC(Preset="Placebo", FPSDivisor=1, Edithreads=4)
Lanczos4Resize(768,576)
Prefetch(18)

My CPU has 10 cores & 20 threads.

Then opening that avisynth file back up in VirtualDub, and encoding the output via H264. However every now and then in the video, I get random parts where it looks like the de-interlacing has failed, or i'm seeing repeated/out of sequence frames. You can see this from around 55 - 120 secs into the attached file. When capturing, VirtualDub shows zero dropped frames. Is there anything i'm doing wrong, either something I need to check when capturing, or is my AviSynth script wrong? This has happened on every single video i've captured so far, across a variety of tapes.

[poisondeathray]

To rule out script problems (maybe with QTGMC, prefetch), check the original file with AssumeTFF().SeparateFields() only

Then check again with FFmpegSource2(threads=1) , and another source filter like LWLibavVideoSource . It's unlikely to be a source filter issue with an uncompressed source, but check anyways

[bergqvistjl]

To rule out script problems (maybe with QTGMC, prefetch), check the original file with AssumeTFF().SeparateFields() only

Then check again with FFmpegSource2(threads=1) , and another source filter like LWLibavVideoSource . It's unlikely to be a source filter issue with an uncompressed source, but check anyways

Nope, the issue is still occuring when trying all of those

[lordsmurf]

You lack a frame TBC. That's the problem.

Magewell (and Blackmagic) are terrible cards at SD capture, and are known for excessive dropped frames (reported or not).

What is happening here is entirely expected. Bad, but expected.

Get a TBC, better capture card, case closed.

[dellsam34]

Are the artifacts found in the lossless capture files? If not then you know it's filter related. I have a feeling that this is an encoding problem.

[bergqvistjl]

You lack a frame TBC. That's the problem.

Magewell (and Blackmagic) are terrible cards at SD capture, and are known for excessive dropped frames (reported or not).

What is happening here is entirely expected. Bad, but expected.

Get a TBC, better capture card, case closed.

Darn. This is the 3rd capture card i've bought, and they're all rubbish it seems. What capture card do you use?

[poisondeathray]

Darn. This is the 3rd capture card i've bought, and they're all rubbish it seems.

What were the other 2 models ?

[dannyboy48888]

Never could get obs or virtualdub to capture properly without doing odd stuff or losing sync. Now I use ffmpeg and don't have issues. Such example for my 955q s-video:

ffmpeg -f dshow -video_size 720x480 -framerate 29.97 -crossbar_video_input_pin_number 2 -crossbar_audio_input_pin_number 4 -i video="Hauppauge Cx23100 Video Capture":audio="Hauppauge Cx23100 Video Capture" -c:v ffv1 -c:a flac -t 01:05:00 test.mkv

[dellsam34]

Assuming a component is at fault and just keep buying more components is not a good strategy, You have to narrow down your problem like I mentioned in Post #5. And as Dannyboy mentioned, try another capture software, vdub is filled with options and if you get some of them wrong your capture will have problems.

[bergqvistjl]

Darn. This is the 3rd capture card i've bought, and they're all rubbish it seems.

What were the other 2 models ?

Hauppage Colossus 2, and Avermedia CE3210B. So far the magewell has had the far superior picture quality & reliability, just a shame about the dropped frames.

Colossus 2, I couldn't capture without using their own encoders, which I didn't like - and the card kept locking up, losing its colour & requiring me to reboot all the time.

The Avermedia had just awful blurry picture quality. The Magewell is perfect aside from the badly dropped frames every now and then.

[bergqvistjl]

Assuming a component is at fault and just keep buying more components is not a good strategy, You have to narrow down your problem like I mentioned in Post #5. And as Dannyboy mentioned, try another capture software, vdub is filled with options and if you get some of them wrong your capture will have problems.

I've checked and the dropped/dodgy frames are definitely in the source AVI file, so yeah i'm pretty sure it's the capture card now.

[dellsam34]

Do you know that the card has a setting menu that you can access from the Magewell application (not for capturing, just settings). If you haven't done so install it and see what you got under the default settings.

[johnmeyer]

I think there is a good chance that some of these replies are off the mark. If it were a capture card problem, you'd see that immediately after capture, before you performed any work with AVISynth.

Looking at your script, the answer seems obvious to me, and it is easy to test if this is true: multi-threading failure.

I have seen frames get out of order when using AVISynth multithreading. To test this theory, run the script again, using the same exact input that results in out of sequence fields and/or frames. However, before running, comment out the Prefetch line. I'll bet this fixes the problem. If it does, read up on the RequestLinear command, and also look at what version of AVISynth you have. You may also need to modify the SetFilterMTMode parameters.

So, re-do the work with multi-threading disabled, and then try again with different SetFilterMTMode settings. If that doesn't work, try different versions of AVISynth. You may also need to specify MVTools2 directly in a second SetFilterMTMode line. You might also see if there have been any posts about using multithreading with QTGMC.

Another thing to try is to use a much simpler deinterlacer.

[dellsam34]

I think he said in post #11 the problem is in the captured footage before any AVIsynth work. While the card is decent and might have some sort of stabilization I think the only way to find out for sure where the problem is, is to access the card menu.

[lordsmurf]

If it were a capture card problem, you'd see that immediately after capture,

Yes and no.

- See it immediately? Not necessarily. In fact, not likely. This is only noticed farther into processing the captures.
- But still present? Absolutely, this is a known defect of these two brands of HD cards. The SD sucks, and is an apparent afterthought feature.

Years ago, almost a decade ago, I had actually suggested the BM card as a potential game-changer card. Early tests looked good. But then users saw the flaws. And I wasn't even the one that found the flaw. But I was able to replicate it easily. Even with a quality TBC, the SOB card would drop and dupe frames -- and do it WITHOUT REPORTING! That's really bad.

I have seen frames get out of order when using AVISynth multithreading.

And garbled frames. This is why I no longer use any MT. (But this is unrelated to the OP issue here.)

[bergqvistjl]

Do you know that the card has a setting menu that you can access from the Magewell application (not for capturing, just settings). If you haven't done so install it and see what you got under the default settings.

I only have the capture application - where can I download the settings application?

On the subject of settings - is this right for the capture timing options in VirtualDub, and are my DirectShow options correct here?

[Attachment 56153 - Click to enlarge]

[bergqvistjl]

If it were a capture card problem, you'd see that immediately after capture.

When viewing the raw AVI file straight after capture, I can see it there too unfortunately. So I'm ruling out something wrong with my AviSynth config

If it were a capture card problem, you'd see that immediately after capture,

Yes and no.

- See it immediately? Not necessarily. In fact, not likely. This is only noticed farther into processing the captures.
- But still present? Absolutely, this is a known defect of these two brands of HD cards. The SD sucks, and is an apparent afterthought feature.

Years ago, almost a decade ago, I had actually suggested the BM card as a potential game-changer card. Early tests looked good. But then users saw the flaws. And I wasn't even the one that found the flaw. But I was able to replicate it easily. Even with a quality TBC, the SOB card would drop and dupe frames -- and do it WITHOUT REPORTING! That's really bad.

I have seen frames get out of order when using AVISynth multithreading.

And garbled frames. This is why I no longer use any MT. (But this is unrelated to the OP issue here.)

What PCI-E capture card would you recommend instead of my Magewell one?

[dellsam34]

The control application can be downloaded from the manufacturer website. It should have all the setting for the frame, in and outs and procamp.