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[wer]

I'd like to request a reconsideration of the "Aggressive" deinterlacing default in ROHQ/LAV.

The Aggressive deinterlacing setting in LAV has been an issue for quite a few users for many years.  Back in 2015 it was agreed to change the default to "Auto" for certain types of content, in order to better handle DVDs.

Quite a few years have gone by.  Hard drive space is cheap.  New purchases are bluray, unless the title is only available on DVD.  But I'm not using discs anymore.  All my DVD's are ripped lossless to files.  Almost all are MKV, but some of the older ones might be VOB or MPG.

The vast majority of them are progressive.  And Red October HQ with LAV detects all those progressive rips as interlaced.
That means they get played back at 29.97 with deinterlacing turned on instead of 24p.  So they have some cadence issues, etc. 

Mediainfo has no trouble identifying them as 23.976FPS progressive, but MC plays them back with deinterlacing anyway.  I also have a number of files that lack both the progressive or interlaced flags, and have FPS of 29.97, that play fine with interlacing forced off, indicating they are actually progressive.

Since RO HQ is for High Quality, it would seem like playing back progressive as progressive would be a good thing.

Red October is all about handling things simply for the user.  Getting progressive content to play should be simple.

If extending the "Auto" default to MKV/MPG/VOB files is considered too drastic a change, could we please at least have an option the user could check to relax the deinterlacing, so that MC with Red October HQ can play back progressive DVD rips correctly?

[Hendrik]

The vast majority of them are progressive.  And Red October HQ with LAV detects all those progressive rips as interlaced.
That means they get played back at 29.97 with deinterlacing turned on instead of 24p.  So they have some cadence issues, etc. 

This happens because they are in fact not proper progressive. DVDs don't even allow progressive video. Progressive content on DVD is either Telecined to 29.97 (in the US) or using PsF (for PAL), both of which appear as interlaced video until deeper inspection.

"Aggressive" deinterlacing won't make progressive video into interlaced, it has to detect interlaced video to begin with to even do anything - which DVDs are.
It exists to fix broken TV broadcasts, which are still as relevant today as the day the option was introduced, unfortunately.

If the video is actually properly marked as being Soft-Telecined, which many DVDs are, LAV and madVR might tell you that the content is interlaced, but there is not actually any deinterlacing happening, since the individual frames are marked as progressive within an interlaced stream.

[wer]

Thanks for your reply, Hendrik.

I believe the content on a DVD can be stored as soft-telecine, in which the frames are stored progressive at 23.976 and flags are inserted to instruct the player to duplicate frames as needed to get to 29.97.  You told me that once, too.   The correct playback rate for these is 23.976.  Other tools identify the content as such, but not MC.

I've read before that the DXVA deinterlacer doesn't reveal what it's doing, so fair enough that there's no way to tell if actual deinterlacing is applied.

But the madvr OSD says deinterlacing is on(upstream) and the refresh rate is set to 59.94 to accommodate the 29.97 framerate, and visual stuttering occurs.  And that's not good.

Moreover, the deinterlacing being on still interferes deleteriously, and I can prove it.  Here's what happens you you play movies like this (mediainfo readout below) in MC at different refresh rates: (Case 1 is ROHQ Default)
Case 1:  29.97  Deint on:         Stutters
Case 2:  29.97  Deint forced off: Stutters
Case 3: 23.976  Deint on:         Stutters worse
Case 4: 23.976  Deint forced off: PERFECT

The difference between cases 3 and 4 is deactivating deinterlacing.  In order to get to Case 4, and correct playback, currently several manual tricky things must be done that lots of people don't know how to do.  That shouldn't be necessary since this is such a common case.  Changing the FPS can be done through the MC interface, but forcing the deint off cannot, and both actions are required for correct playback.

What I'm saying is that we should let people playback their 23.976 progressive DVDs at the correct framerate without stutter, without making the user jump through a lot of hoops.

------------------
Video
ID                                       : 224 (0xE0)
Format                                   : MPEG Video
Format version                           : Version 2
Format profile                           : Main@Main
Format settings                          : CustomMatrix / BVOP
Format settings, BVOP                    : Yes
Format settings, Matrix                  : Custom
Format settings, GOP                     : M=3, N=12
Duration                                 : 1 h 39 min
Bit rate mode                            : Variable
Bit rate                                 : 5 445 kb/s
Maximum bit rate                         : 7 500 kb/s
Width                                    : 720 pixels
Height                                   : 480 pixels
Display aspect ratio                     : 4:3
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Scan order                               : 2:3 Pulldown
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.657
Time code of first frame                 : 00:59:58:00
Time code source                         : Group of pictures header
GOP, Open/Closed                         : Open
GOP, Open/Closed of first frame          : Closed
Stream size                              : 3.79 GiB (95%)

[Hendrik]

What I'm saying is that we should let people playback their 23.976 progressive DVDs at the correct framerate without stutter, without making the user jump through a lot of hoops.

And what I am saying is that there is no such thing as a "23.976 progressive DVD" without some liberal interpretations that apparently MediaInfo took to stop users asking about it, I suppose. Instead, what you have is a 29.97 video with some frames "missing", which does happen to have 23.976 frames per second, but in a different manner then a proper 23.976 video would.

That those videos are being detected as 29.97 is entirely correct, since without some in-depth inspection you cant really tell that those frames are "missing". It is in fact a 29.97 FPS DVD, with what basically is an optimization to avoid coding a bunch of frames (instead, metadata to tell it which ones to repeat).

In short, DVDs were a terribly short-sighted format - at least in NTSC. PAL DVDs have different issues, but at least 25/50 fps are just clean multiples and not a 3:2 factor.

Anyhow, what I can probably do is disable the aggressive deinterlacing when the FPS is 23.976 or 24, since those frame rates should never be interlaced. You would still have to manually change them to 23.976 if you remuxed them without fixing the timestamps/frame rate, but at least they should avoid any surprises then.

[wer]

I understand and agree with your point about DVD video.  I'm a neophyte with it compared to you, but when I first started learning about the intricacies of it I was appalled at the contradictions and general sloppiness that goes on.  It's a real hodgepodge.

But this is the world we live in, and given the laxity of what goes on with DVD video, perhaps liberal interpretations are the only ones that make sense.  If there is video encoded on a disc that must be played to 23.976 and without deinterlacing to be played correctly, the distinction between that and a stricter definition of progressive is at best of academic interest to an end user. They just want their video to play right.

Just deactivating the interlacing would be a good step, and shouldn't cause any harm.  People would still need to know to manually change [FPS], but at least they have access to that.

But couldn't MC detect the needed 23.976 framerate, either when the video is imported, or during audio analysis?  I don't know exactly what Mediainfo is doing to derive its information, but it does it in a fraction of a second; it's certainly not looking at the entire file.  I also tried the Gspot utility, and it says 23.976 too.

If MC could do the same detection during import or audio analysis, the whole experience would be seamless for the end user.  "Detect pseudo-progressive DVD video" could be an option, just like HDCD detection, if for some reason you think it's too dangerous to be the default.