What's Going On with the Interlacing Here?

[koberulz]

Not sure how to cut the MKV file losslessly, so I've made a lossless AVI of it. It was originally created from a DVD via MakeMKV.

It lists with no interlacing information at all, so I pulled it into VDub and bobbed it TFF to check that TFF was correct...but it isn't. Every fourth frame of the resulting file jumps backwards. BFF doesn't work either. What's going on here?

Here's the MediaInfo for the original MKV:

General
Format                                   : Matroska
Format version                           : Version 4 / Version 2
File size                                : 7.04 GiB
Duration                                 : 2 h 48 min
Overall bit rate mode                    : Constant
Overall bit rate                         : 5 997 kb/s
Encoded date                             : UTC 2020-01-11 14:04:32
Writing application                      : mkvmerge v40.0.0 ('Old Town Road + Pony') 64-bit
Writing library                          : libebml v1.3.9 + libmatroska v1.5.2

Video
ID                                       : 2
Format                                   : MPEG Video
Format version                           : Version 2
Format profile                           : Main@Main
Format settings, BVOP                    : Yes
Format settings, Matrix                  : Default
Format settings, GOP                     : M=5, N=8
Codec ID                                 : V_MPEG2
Codec ID/Info                            : MPEG 1 or 2 Video
Duration                                 : 2 h 48 min
Bit rate mode                            : Constant
Bit rate                                 : 5 800 kb/s
Width                                    : 720 pixels
Height                                   : 576 pixels
Display aspect ratio                     : 4:3
Frame rate mode                          : Variable
Frame rate                               : 50.000 FPS
Original frame rate                      : 25.000 FPS
Standard                                 : PAL
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.280
Time code of first frame                 : 00:00:00:00
Time code source                         : Group of pictures header
GOP, Open/Closed                         : Open
GOP, Open/Closed of first frame          : Closed
Stream size                              : 6.81 GiB (97%)
Writing library                          : TMPGEnc 2.524.63.181
Default                                  : Yes
Forced                                   : No
Color primaries                          : BT.601 PAL
Transfer characteristics                 : BT.470 System B, BT.470 System G
Matrix coefficients                      : BT.601

Audio
ID                                       : 1
Format                                   : AC-3
Format/Info                              : Audio Coding 3
Mode extension                           : CM (complete main)
Format settings, Endianness              : Big
Codec ID                                 : A_AC3
Duration                                 : 2 h 48 min
Bit rate mode                            : Constant
Bit rate                                 : 192 kb/s
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 31.250 FPS (1536 spf)
Bit depth                                : 16 bits
Compression mode                         : Lossy
Delay relative to video                  : 520 ms
Stream size                              : 231 MiB (3%)
Title                                    : Dolby Digital 2.0
Language                                 : English
Default                                  : Yes
Forced                                   : No

[babygdav]

Plays fine on my laptop running mphc and vlc.

https://m.dvdfab.cn/resource/video/mkv-editor
Avidemux might edit mkv free.
https://mkvtoolnix.download/doc/mkvextract.html

[koberulz]

Plays fine in VLC for me too, but the Emby web player doesn't deinterlace it which is why I started investigating.

[manono]

Cut out your M2Vs using DGIndex and don't create useless MKVs.

Why did you create a 50fps interlaced video for upload, with every other frame a duplicate? You didn't bob it. You only duplicated every frame. With the dupes removed it's just a normal TFF interlaced video.

[koberulz]

I didn't do anything to the attached AVI, I disabled the bob after testing in VDub.

No M2V ever existed, I created an MKV using MakeMKV, as I said.

[davexnet]

Is it possible the conversion to Lagarith duplicated the frames? A simple script can restore fluid movement:

LWLibavVideoSource("C:\Users\davex\Downloads\inter lacing.avi")
selecteven()
assumetff()
bob() # or qtgmc

[koberulz]

No, the duplicated frames are in the original. Never saw it because I skipped straight to testing the field order. Throwing out either the odd or even frames and then bobbing still leaves a lot of combing though.

And doesn't explain why there are duplicated frames in the first place. I was hoping to handle this without re-encoding anything, seeing as it's originally from a DVD and therefore should be DVD-compliant.

[DB83]

Not really my subject but.....

The original mkv might have had 50 fps yet the original dvd would have had 25 fps (even the mediainfo report states that). So the interlaced dvd became a progressive mkv with the duplicate frames.

[manono]

No M2V ever existed, I created an MKV using MakeMKV, as I said.

It was originally created from a DVD via MakeMKV.

You created the MKV from the DVD? If so, my original statement remains; extract the M2V using DGIndex. The DVD wouldn't have been 50fps. If you didn't use the DVD, then extract the M2V from the MKV and use DGIndex to cut the sample.

The reason neither TFF nor BFF worked for you was because you were "bobbing" the already ruined interlaced 50ps video. This whole thread is a waste of time. Have you learned nothing from your time here?

Throwing out either the odd or even frames and then bobbing still leaves a lot of combing though.

No, it doesn't.

[koberulz]

It does for me. Specifically the edges of the red sign.

I created the MKV from the DVD using MakeMKV, as I've said twice now. I'm backing my discs up onto a media server. I'm not actually trying to do anything with the video files, editing-wise, so why would I create an m2v? MakeMKV doesn't edit or convert or anything so the files should be identical.

As for creating and M2V from the MKV, I don't know how to do that. tsMuxer gets me an MPV file, which DGIndex can open, but it won't let me cut a sample (the start/end buttons are greyed out).

[poisondeathray]

It's the way makemkv is packaging the mkv and timestamp handling.

Some programs misinterpret the field rate as the frame rate, and you get these sorts of problems. It looks like vdub or whatever decoder you're using in vdub is having this issue, so the AVI has the duplicates.

The original does not. I repeat - the m2v or original will not have that problem, and most programs will handle the original properly - you can be almost certain. This is a well known, and common problem with makemkv with interlaced mpeg2 in mkv container

You can use mkvextract or some gui for it like gmkvextractgui to extract the .m2v , then use DGIndex

DGIndexNV can properly read m2v in mkv container, but not free

I'm not actually trying to do anything with the video files, editing-wise, so why would I create an m2v? MakeMKV doesn't edit or convert or anything so the files should be identical.

Because of the messed up timestamps . Because of the problems with interleaced MPEG2 in MKV. A large % of programs/hardware will not handle it properly. Like you're seeing right now.

[manono]

...so why would I create an m2v?

To create a usable sample.

I'm backing my discs up onto a media server.

If that's the crap you put into your media server, better might be to giive it MPGs, if it'll play those okay.

It does for me. Specifically the edges of the red sign.

I don't know what you're seeing but it's almost - by definition - impossible for bobbed videos to display interlacing. Aliasing, maybe, or chroma bleed. Using this script:

ChangeFPS(25)
AssumeTFF()
Yadif(Mode=1)

I see nothing unusual around that red sign as the wrestler passes by.

[koberulz]

Because of the messed up timestamps . Because of the problems with interleaced MPEG2 in MKV. A large % of programs/hardware will not handle it properly. Like you're seeing right now.

TBH it seemed okay on my TV, it just played back combed on the web and when I had a look at Emby's Media Info section it specifically says it's 50fps progressive. I was thinking I just needed to change a flag somewhere in the header or something.

[poisondeathray]

Because of the messed up timestamps . Because of the problems with interleaced MPEG2 in MKV. A large % of programs/hardware will not handle it properly. Like you're seeing right now.

TBH it seemed okay on my TV, it just played back combed on the web and when I had a look at Emby's Media Info section it specifically says it's 50fps progressive. I was thinking I just needed to change a flag somewhere in the header or something.

I bet the interlace flag is there in the original. If it's a retail DVD it should be.

But "Writing library : TMPGEnc 2.524.63.181" suggests it is not, and it might not be a properly made DVD

You can try restream or dvd patcher to flag it (but neither work on a MKV, you need ... surprise, surprise, a m2v)