Correct procedure for sync'd dvd from 23.976 source

[DarkShadow]

I am tv capturing and need some help to get a sync'd final dvd file.

I capture with Virtualdub with the following settings
720x480res 23.976fps video
PCM 48000hz stereo audio

Convert audio/video with cce 2.66 with default settings except turn on dvd compliance

Then a pulldown with dopulldown default settings

Then when checking mp2 audio is correct length but video is 7 minutes short

mplexing gives unsync'd video

[FulciLives]

Hello

You can't capture at 23.976fps

Assuming your source is NTSC you should capture at 29.97fps

You can always try doing IVTC (inverse telecine) AFTER the capture. Most (well at least many) NTSC sources can be inverse telecined back to 23.976fps unless it was originally shot-on-video or is animation (in which case GOOD LUCK trying to get it to 23.976fps).

HOWEVER ...

In my opinion when you take a 29.97fps source and inverse telecine to 23.976fps the picture is usually very "soft" looking. I would only recommend doing that if you intend to watch it on a progressive only display (such as a computer monitor). Otherwise the image will be better if you just leave it at the original 29.97fps

- John "FulciLives" Coleman

[DarkShadow]

Hello

You can't capture at 23.976fps

Assuming your source is NTSC you should capture at 29.97fps

You can always try doing IVTC (inverse telecine) AFTER the capture. Most (well at least many) NTSC sources can be inverse telecined back to 23.976fps unless it was originally shot-on-video or is animation (in which case GOOD LUCK trying to get it to 23.976fps).

HOWEVER ...

In my opinion when you take a 29.97fps source and inverse telecine to 23.976fps the picture is usually very "soft" looking. I would only recommend doing that if you intend to watch it on a progressive only display (such as a computer monitor). Otherwise the image will be better if you just leave it at the original 29.97fps

- John "FulciLives" Coleman

Actually capturing @ 23.976 works fine and is 20% smaller and my only problem is with cce since tmpgenc uses these files fine but is slower and doesn't give the same picture quality

[Vejita-sama]

Well you can capture at any resolution and framerate that you want. But if you capture at say 8fps from a 29.97fps source you have to expect some sync problems; after all you just changed the framerate.

Also the size of a encoded MPEG file is based on the bitrate (and runtime), NOT the framerate. I think you might be confusing the often mention 'idea' that encoding at 23.976fps gives a '25% increase in bitrate for the same file size.'

Anyway, the bottom line is that your sync problems are caused by capturing at a framerate different from your source. You need to capture at 29.97fps (since it appears that that is the framerate of your source: VHS, DV, etc).

IF your source is telecided, you can run an IVTC process to get a 23.976fps video to work with. But more than likely if it's VHS it's a true interlaced source and should be left at 29.97fps.

[DarkShadow]

You have to realize I have been using 23.976 for a long time and it worked perfect and there are no sync problems when the file is converted to dvd using tmpgenc.

The 20% smaller file is the source not final.
example with real numbers:
90 minutes 23.976 source is 35gb
90 minutes 29.976 source is 42gb
which is a 7 gb difference

[FulciLives]

You have to realize I have been using 23.976 for a long time and it worked perfect and there are no sync problems when the file is converted to dvd using tmpgenc.

The 20% smaller file is the source not final.
example with real numbers:
90 minutes 23.976 source is 35gb
90 minutes 29.976 source is 42gb
which is a 7 gb difference

If the source is 29.97fps then you can't capture at 23.976fps
I'm not aware of any capture device (at least not any common consumer level capture devices) than can accept a progressive 23.976fps source. So my guess is that your source is 29.97fps and that you MUST therefore capture at that frame rate. As I said you can always IVTC after the capture to 23.976fps but please remember that not ALL NTSC source material (that is 29.97fps) can be properly IVTC'ed down to 23.976fps

Also I understand that encoding at 23.976fps takes up less space than encoding at 29.97fps but if the original source is 29.97fps I find that even if you CAN do a proper IVTC the result is "soft" looking ... not nearly as sharpt as say a true progressive NTSC DVD which has a 23.976fps format (with 3:2 pulldown for 29.97fps playback). I'm sure other people have noticed this and those that have will most likely agree with me that you should leave a 29.97fps source at 29.97fps unless you NEED it to be progressive (23.976fps) for your display (i.e., a computer monitor).

- John "FulciLives" Coleman