VCDs/SVCDs at 23.976 fps

Introduction

Some NTSC videos are telecined, which means that they have been converted from 24 fps to run at 29.97 fps on standard NTSC televisions.  Running this type of video through an inverse telecine program restores the original ~24 fps video and increases the video quality.  (See my article about Telecining for more information.)  In general, it's always a good idea to inverse telecine a video if it has been NTSC telecined.  However, when producing video for a VCD or SVCD, certain issues arise.

The Problem

Unfortunately, many SVCD/VCD players can't handle discs that have been inverse telecined to run at 23.976 fps.  This is strange because 23.976 fps VCDs are definitely included in the VCD standard and 23.976 fps SVCDs are very likely supported by the SVCD standard.  (The SVCD standard only supports an NTSC frame rate of 29.97 fps, but the frame rate of a 23.976 fps MPEG-2 video encoded with the 3:2 pulldown option technically is 29.97 fps.)  Because of possible incompatibilities, you have to be careful when trying to inverse telecine video for a VCD/SVCD.

What Should I Do?

The first thing you should do is determine whether or not your player can handle VCDs or SVCDs at 23.976 fps.  One way to do this is to create a 23.976 fps VCD/SVCD and test it out for yourself.  Another option is to head over to www.vcdhelp.com and check their DVD player compatibility list or post a question in their forum.  There's a chance that someone with the same player as you will have tested it out.

If you discover that your player does support VCDs/SVCDs at 23.976 fps, then you can inverse telecine your video as described in Step #2 of my High Resolution Video Processing page.

If you find out that your player does not support VCDs or SVCDs at 23.976 fps, then you have a couple of options:

A)  You can specially inverse telecine your video to remove the interlacing artifacts but retain a video that plays at 29.97 fps.  The output video will be just like a video that has been properly inverse telecined, except that it will have 1 duplicated frame for every group of 5 frames.  The duplicated frame will be very easy to compress, so the quality will be relatively high.  However, the frame duplication will make movement in the video appear more jerky.

B)  If you're making a SVCD, then you don't have to inverse telecine your video at all.  SVCDs, which use MPEG-2 compression, fully support the interlacing found in a telecined video.  By choosing to leave your video as interlaced, the movement in your video will be as smooth as possible.  However, since the interlaced video will be harder to compress, the image might not look as good, and there may be more blocking artifacts.

Option A:  To carry out option A, do the following instead of Step #2 in my High Resolution Video Processing page.

1)  Click on Video -> Filters -> Add and double-click 'telecide' in the list.  (The Telecide plug-in is available from my VirtualDub Plug-ins page.)  You can leave the settings at their defaults, which should look like the image below:

Click OK twice to return to the main VirtualDub window.

2)  Since the Telecide filter introduces a one-frame delay in your video, the audio will be desynchronized by one frame.  To fix this, first click on Audio -> Interleaving.  Then change the "Delay audio track by" option to 33 since your video is NTSC (29.97 fps).  You do not need to alter any other options, so just click OK when you are finished.  The settings should look similar to this:

3)  Continue with Step #3 on my High Resolution Video Processing page.

Option B:

Simply ignore Step #2 on my High Resolution Video Processing page and do not carry out any inverse telecine.  Just go on with Step #3.