480i Inverse Telecine - Audio Falling in/out of Sync

[ThaKarra]

Hi all,

I just want to start off by saying, I'm VERY new to this so please forgive me if I use the wrong terminology or I'm doing something completely wrong. I'm trying to learn as I go along and I'm probably making very obvious mistakes.

So I have some 720x480 cartoon episodes I'm ultimately trying to restore and upscale. However the episodes are interlaced in a "weird way". When I skip through the episodes in VLC only certain parts of the video are visually interlaced.

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                     : Variable
Format settings, picture structure       : Frame
Codec ID                                 : V_MPEG2
Codec ID/Info                            : MPEG 1 or 2 Video
Duration                                 : 22 min 37 s
Bit rate mode                            : Variable
Bit rate                                 : 4 584 kb/s
Maximum bit rate                         : 9 800 kb/s
Width                                    : 720 pixels
Height                                   : 480 pixels
Display aspect ratio                     : 4:3
Frame rate mode                          : Variable
Frame rate                               : 24.222 FPS
Original frame rate                      : 29.970 (30000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Interlaced
Scan order                               : Top Field First
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.548
Time code of first frame                 : 00:59:59;00
Time code source                         : Group of pictures header
Stream size                              : 742 MiB (96%)
Language                                 : English
Default                                  : No
Forced                                   : No
Original source medium                   : DVD-Video

I was very tempted to run them through Handbrake or VirtualDub and just apply a deinterlace filter but lately I've been learning about basic inverse telecine using AvsPmod.

This is the script I'm using (I'm probably doing something majorly wrong here):

MPEG2Source("G:\Encode\0102.d2v")
tfm()
tDecimate()
bilinearResize(720,540)
vinverse()
crop(0,0,720,538)

So far everything is working perfectly. I import the script into VirtualDub and the video looks perfect. The interlacing is visually gone and the frame rate is fixed 23.976.

Where is starts to fall apart is the audio. I cant attach the source video file as audio because VirtualDub doesn't like using .mkv files as source audio and it throws an error. So I used Kirara to convert the source video file into a .WAV file (which VirtualDub will happily accept as an audio source).

Now when I play everything back within VirtualDub, everything seems fine at first, everything appear to be in-sync.. But as I start skipping through into the middle of the episode I notice its slightly fallen out of sync. Then suddenly after a few minutes it'll be okay again and then back out. It's like certain areas are falling in and out.

Would appreciate any help. Please keep in mind that I'm a total noob when it comes to this kind of stuff. So if you could please kindly ELI5, I would appreciate it.

[davexnet]

Do you want to re-encode the audio or use the existing audio as-is?

If you want to use the existing audio, create your new video then mux the old audio
in mkvtoolnix GUI

[ThaKarra]

Do you want to re-encode the audio or use the existing audio as-is?

If you want to use the existing audio, create your new video then mux the old audio
in mkvtoolnix GUI

Honestly at that point I would have been happy with any audio that was in-sync.

However I think I've fixed it now.

I've stopped using DGIndex and:

MPEG2Source("G:\Encode\0102.d2v")

I installed L-SMASH-Works and now I'm using:

LWLibavVideoSource("G:\Encode\0102.mkv")

Seems to give me better results now.

[manono]

I've stopped using DGIndex...

Don't.

Now when I play everything back within VirtualDub, everything seems fine at first, everything appear to be in-sync.. But as I start skipping through into the middle of the episode I notice its slightly fallen out of sync.

Means nothing. VDub can't be used as a player to check audio synch. Have you played the script itself? Have you encoded the video and checked the audio synch?

An IVTC doesn't change the length of the video. If it was in synch before, it'll be in synch afterwards. The only thing that might affect that is if there was an audio delay in the initial video, a delay not taken into account in the reencode. DGIndex, when demuxing the audio, tells you if there's an audio delay. Also, rarely, a different Cell ID might have its own audio delay that's taken into account in the DVD but not in your reencode. Rarely. You can check for that using PGCDemux.

[jagabo]

Make sure DgIndex is set to Video -> Field Operation -> Honor Pulldown Flags. Then rebuild your index.