Quick, simple guide to QTGMC deinterlacing (for newbies)

[pm-s]

QTGMC is best deinterlacing algorithm i know, but not many people know how to use avisynth. that's the reason im making this.

1. Install Hybrid
2. Insert your footage into the program (by dragging it to the first textbox or selecting it with the icon next to it)
2.5. select passthrought all on audio dropdown menu
3. go to x264 tab. on the bitrate (kbit/s) change it to at least 7000 for standard definition video or 18000 - 20000 for 1080px or 13000 for 720px
4. go to the filtering tab and "Deinterlace/telecine" sub-tab
5. be sure "use" is selected and "qtgmc" is chosen
6. change preset to "very slow" or placebo.
7. if you want the double framerate (50fps as opposed to 25fps, for example) also check "bob"
8. go back to the first base tab and after default container choose the output place
9. click the man with shovel and wait from all green lines to complete
10. thats it

[Barrythecrab]

That's a nice qwik-start.
Please note: on my system Lagareth codec was not being recognized to properly BOB the video from 60i to 60P.
Please note: I get choppy stuttery video unless I tick LIBAV video source.
Your results may differ.

[magnu]

Thanks so much for doing this! One question. If I want to double framerate you say about selecting Bob. I assume what you are saying here is to use other software to double the framerate after using Hybrid, or does Hybrid do it too?

I found the answer and just came across this video which explains how to do it:- https://www.youtube.com/watch?v=-uihfyMxuHs

[Barrythecrab]

Hybrid does it all.

[magnu]

The settings in the video would be different obviously when combining those two conversions, or should they be done separately?

[magnu]

Two quick questions:-

To change the Framerate, etc., I need to change the Support Setting from VapourSynth to AviSynth. When I do this it doesn't do Deinterlacing. Is there any way I can do all in one?

Does Hybrid have a Save Settings type of option?

[Alwyn]

Using Hybrid version 2021.04.12.1

My video (a LAGS interlaced AVI from a Vdub VHS capture) is coming out Interlaced. It seems as though QTGMC isn't running, because my processing speed is much faster than I expected. I'm getting around 25fps processing time whereas I was expecting around 5fps at the most.

Mediainfo is saying my Hybrid output is progressive but opening it in VDub definitely shows it's interlaced, and applying a deinterlace filter removes the jaggies.

Here are my settings:


[Attachment 58789 - Click to enlarge]


[Attachment 58790 - Click to enlarge]


[Attachment 58791 - Click to enlarge]

My VHS capture audio is PCM so I had to set the audio to "Custom" on the Base page, then this on the audio tab:

[Attachment 58792 - Click to enlarge]

Output is Interlaced. Any corrections to what I've set would be gratefully accepted.

[Alwyn]

I then gave it a progressive AVI (deinterlaced with VDub; definitely no jaggies) and Hybrid says it is Bottom Field First when I click the ? mark next to "QTGMC (Vapoursmith)".

[pm-s]

Thanks so much for doing this! One question. If I want to double framerate you say about selecting Bob. I assume what you are saying here is to use other software to double the framerate after using Hybrid, or does Hybrid do it too?

I found the answer and just came across this video which explains how to do it:- https://www.youtube.com/watch?v=-uihfyMxuHs

no thats frame intrepolation, and it tries to predict nonexistent frames.

see, bob uses both fields and gives the footage its original high framerate.
normal setting deletes every odd (or even) frame.

this is how the easiest type of bob works https://www.100fps.com/why_bobbing.htm giving 288p50 footage

QTGMC is way more advanced. what it does is it uses odd fields to predict even ones (or vice versa), and it gives near perfect full resolution output.

[pm-s]

Using Hybrid version 2021.04.12.1

My video (a LAGS interlaced AVI from a Vdub VHS capture) is coming out Interlaced. It seems as though QTGMC isn't running, because my processing speed is much faster than I expected. I'm getting around 25fps processing time whereas I was expecting around 5fps at the most.

Mediainfo is saying my Hybrid output is progressive but opening it in VDub definitely shows it's interlaced, and applying a deinterlace filter removes the jaggies.

Here are my settings:


[Attachment 58789 - Click to enlarge]


[Attachment 58790 - Click to enlarge]


[Attachment 58791 - Click to enlarge]

My VHS capture audio is PCM so I had to set the audio to "Custom" on the Base page, then this on the audio tab:

[Attachment 58792 - Click to enlarge]

Output is Interlaced. Any corrections to what I've set would be gratefully accepted.

probably your capture card problem

try setting sensitivity to 100 it may help with interlaced videos save progresive

[Alwyn]

try setting sensitivity to 100 it may help with interlaced videos save progresive

Didn't work, Hybrid is encoding into MP4 but not QTGMCing.

What codecs (video and audio) are your files that you are using in Hybrid?

[Alwyn]

5. be sure "use" is selected and "qtgmc" is chosen

Out of interest, exactly what does your dropdown say here? Mine says "QTGMC (Vapoursynth)".

[Barrythecrab]

You will see in image 58791 the input and output frame rate is the same. Output should be twice the input for bobbing.

[Alwyn]

probably your capture card problem

No.

On the Deinterlacing tab, bottom right, one must set "Avisynth" from the "Support:" dropdown (the defualt is Vapoursynth)

and then back up to top left, choose "QTGMC (Avisynth)" from the dropdown.

Then it works.

Also, I set the field order on the Filtering tab (top right): my VHS AVIs were being analysed as Progressive ("Input scan type:") when in fact they are TFF (I assume everybody else's VHS captures are as well), which I set in the drop-down below.

Thanks for getting me going with this though; I really struggle with Avisynth. The image quality is great but there is an ugly colourisation which I'll post about in a new thread.

You will see in image 58791 the input and output frame rate is the same. Output should be twice the input for bobbing.

That ties in with the scan type issue above; leave it on Progressive and you'll get 25 with bob. Change it to TFF you'll get 50 with Bob.

[Selur]

Mediainfo is saying my Hybrid output is progressive but opening it in VDub definitely shows it's interlaced, and applying a deinterlace filter removes the jaggies.

Hybrid won't apply deinterlacing/ivtc-filters if the input scan type is progressive.
If your content isn't properly flagged i.e. when it's flagged as progressive, but really is interlaced you should overwrite the detected scan type (Filtering->(De-)Interlace/Telecine->Deinterlace/Telecine Settings->Overwrite input scan type to') to the proper value.

Does Hybrid have a Save Settings type of option?

-> [INFO] About profiles and saving settings,....

Cu Selur

[Alwyn]

If your content isn't properly flagged i.e. when it's flagged as progressive, but really is interlaced you should overwrite the detected scan type (Filtering->(De-)Interlace/Telecine->Deinterlace/Telecine Settings->Overwrite input scan type to') to the proper value.

I then remembered a post where Jagabo explained how to use the Bobdoubler filter in VDub to work out the interlacing. All my Lagarith VHS captures are TFF so I set that.

Thanks for Hybrid, Selur! I'll make a donation.

[brockway]

Much appreciate the steps above for getting started. In case it helps others, I thought I'd post the steps I found worked for me after reading through this thread and doing a bit of troubleshooting.

0. Install Hybrid
1. Audio: select passthrough on the audio dropdown menu.
1B. If you get an error of "Error in audio job creation Format adpcm is not allowed for mp4 output." (https://forum.selur.net/thread-27.html) when attempting to encode at the end of the steps, then:
- Set Base > Processing > Audio> 'Auto add (all)'
- Enable 'Audio > Main > Audio Encoding Options'. Set audio format & bitrate appropriately.
2. Insert your video into the program (by dragging it to the first textbox or selecting it with the icon next to it)
3. go to x264 tab.
4. For the encoding mode, select "Constant Rate Factor" (CRF), to ensure constant quality. Suggestions include CRF 18-22 (18 for 480p, 20 for 720p). For more discussion see: this thread.
4B. If you have size constraints, then consider choosing "specific filesize/bitrate (2-pass)". Use google to determine bitrate for your resolution.
5. for AVC Profile/Level, set the version appropriately. https://en.wikipedia.org/wiki/Advanced_Video_Coding#Levels
6. go to the filtering tab and change Support to "AviSynth" VapourSynth in bottom right hand corner.
6B. [edit] Selur recommends using VapourSynth over AviSynth (see details below). However Alwyn mentioned that deinterlace was only successful using AviSynth.
7. Go to "Deinterlace/telecine" sub-tab.
8. be sure "use" is selected and "QTGMC (Avisynth)" is chosen
9. change the preset to something between "slower" and "faster" (inclusive). Note that lordsmurf recommends "faster" in this thread post, but the best preset may be specific to your video.
10. if you want the double framerate (50fps as opposed to 25fps, for example) also check "bob"
11. Click the checkbox next to "Overwrite input scan type to". Set it appropriately. Selur wrote "Hybrid won't apply deinterlacing/ivtc-filters if the input scan type is progressive."
11B. Hybrid can perform interlace detection on the video and recommend a setting for scan type. Press the "?" next to "QTGMC (Avisynth)". For VHS footage, it is usually "Top Field First" (TFF).
12. go back to the first base tab and after default container choose the output place
13. click the man with shovel and wait from all green lines to complete

[Selur]

Why are you using Avisynth? (Vapoursynth is faster,...)

[brockway]

Why are you using Avisynth? (Vapoursynth is faster,...)

To be honest, I'm a newbie. I'm not familiar with Vapoursynth, just Avisynth and that knowledge is minimal.

I was just going based on what the user Alwyn wrote above:

On the Deinterlacing tab, bottom right, one must set "Avisynth" from the "Support:" dropdown (the defualt is Vapoursynth)

[Selur]

To be honest, I'm a newbie.

Then at least I would not recommend Hybrid.

That said, the only (to me 'valid') reasons that come to my mind why one should use Avisynth is:
a. you are already familiar with Avisynth and you want to write your own custom Avisynth code
b. you are already familiar with Avisynth and you want/need to use a filter that isn't available (or properly ported) in Vapoursynth
(c. your system is a dual core cpu with <=4gb ram or you Window OS is so old that you can't use current Vapoursynth, but then Hybrid probably won't run properly either )

Cu Selur

[brockway]

To be honest, I'm a newbie.

Then at least I would not recommend Hybrid.

That said, the only (to me 'valid') reasons that come to my mind why one should use Avisynth is:
a. you are already familiar with Avisynth and you want to write your own custom Avisynth code
b. you are already familiar with Avisynth and you want/need to use a filter that isn't available (or properly ported) in Vapoursynth
(c. your system is a dual core cpu with <=4gb ram or you Window OS is so old that you can't use current Vapoursynth, but then Hybrid probably won't run properly either )

Cu Selur

I've noted that the legendary Selur has recommended I go back to using Handbrake

I do very much appreciate your input (and all the amazing work you do). I'll do some research into Vapoursynth - thank you!

[abolibibelot]

4. on the bitrate (kbit/s) change it to at least 7000 for standard definition video or 18000 - 20000 for 1080px or 13000 for 720px

Choosing a specific bitrate is not an efficient method to reach a target level of quality, using a CRF setting should be preferred unless there is a size constraint.

9. change preset to "faster" as per lordsmurf: http://www.digitalfaq.com/forum/video-restore/12192-how-make-vhs.html#post80019

With all due respect, this highly respectable member with a wealth of practical knowledge and proficiency may not be the best authority when it comes to the strict “computing technique” aspect of video things — I've read statements from said member on such aspects which were almost certainly wrong, provably wrong (for instance : lossless encoders are not actually lossless). So what was stated in that post may be true, but I would rather have someone with a consistent track record of reliable in-depth knowledge on those matters confirm the validity of that advice before commiting to it.

I've noted that the legendary Selur has recommended I go back to using Handbrake

Handbrake is supposed to be “fool proof”, but I've seen enough botched encodes made with that tool to come to the conclusion that using said program is like giving a proof that you are a fool.

[brockway]

Thank you for the input! Changes made to original post above.

4. on the bitrate (kbit/s) change it to at least 7000 for standard definition video or 18000 - 20000 for 1080px or 13000 for 720px

Choosing a specific bitrate is not an efficient method to reach a target level of quality, using a CRF setting should be preferred unless there is a size constraint.

I edited my post to say:

4. For the encoding mode, select "Constant Rate Factor" (CRF), to ensure constant quality. Suggestions include CRF 18-22 (18 for 480p, 20 for 720p). For more discussion see: this thread.
4B. If you have size constraints, then consider choosing "specific filesize/bitrate (2-pass)". Use google to determine bitrate for your resolution.

9. change preset to "faster" as per lordsmurf: http://www.digitalfaq.com/forum/video-restore/12192-how-make-vhs.html#post80019

With all due respect, this highly respectable member with a wealth of practical knowledge and proficiency may not be the best authority when it comes to the strict “computing technique” aspect of video things — I've read statements from said member on such aspects which were almost certainly wrong, provably wrong (for instance : lossless encoders are not actually lossless). So what was stated in that post may be true, but I would rather have someone with a consistent track record of reliable in-depth knowledge on those matters confirm the validity of that advice before commiting to it.

I edited my post to say:

9. change the preset to something between "slower" and "faster" (inclusive). Note that lordsmurf recommends "faster" in this thread post, but the best preset may be specific to your video.

[Selur]

lossless encoders are not actually lossless

Example? All lossless encoders I know of are lossless.
In the color spaces (and scan orders) they support of course, so if you compress a 4:4:4 source with a lossless encoder that only supports 4:2:0 it's clear that you will only get a lossless copy of the 4:2:0 representation of the source. I did test this for at least x264, x265, ffhv1, huffyuv and vp9, but I would be surprised if this wasn't true for av1 and ut video and other losselss video formats. (not prores&co which are not lossless, but something they like to call 'visually lossless')

[abolibibelot]

Example? All lossless encoders I know of are lossless.

I was referring to this which I quoted here (and possibly another instance where the same member contested the very notion that any lossless encoder — beside x264 which is not primarily known as such — is actually lossless, which I remember finding quite puzzling considering how competent said member is otherwise, but I couldn't find the discussion in question so I can't guarantee that I did read it).

[Selur]

You are aware that lordsmurf clarified his statement, to that he meant:

Not for capture.

source: https://forum.videohelp.com/threads/393998-VHS-capturing-without-VirtualDub-under-Linux#post2557679

Since Hybrid doesn't do live captures this is not relevant here at all.
Also I'm not sure this is really true if your system is fast enough capturing lossless with x264 should be possible (unless you mess with the color space or scan type, like mentioned before).
That said I never do live captures, so there might be some theoretical restriction I'm not aware of that really hinders lossless live captures, but I really doubt it.

-> from my understanding that statement is simply wrong, problem is with live captures it's hard to prove unless you capture the source twice.

Cu Selur

[ElmoRocks05]

What lossless video codecs do you recommend for better quality compression? I'd like to have the quality to be distinguishable from the original and I prefer not to use H.264 as it's lossy. Or is there a way to use H.264 but keep it lossless?

[poisondeathray]

What lossless video codecs do you recommend for better quality compression? I'd like to have the quality to be distinguishable from the original and I prefer not to use H.264 as it's lossy. Or is there a way to use H.264 but keep it lossless?

h264 can be lossless with x264 encoder using --qp 0

[Selur]

What lossless video codecs do you recommend for better quality compression?

don't use a lossless codec if you want high compression

[ElmoRocks05]

What lossless video codecs do you recommend for better quality compression? I'd like to have the quality to be distinguishable from the original and I prefer not to use H.264 as it's lossy. Or is there a way to use H.264 but keep it lossless?

h264 can be lossless with x264 encoder using --qp 0

How do you do this in Hybrid?