Interlacing or deinterlacing or Film etc experts explain ?

[tokyootaku]

Say for example the source AVI file is in 23.97 something does that quantify it as being a file that needs to be deinterlaced or interlaced then. Can someone explain. I notice that there are some AVI files I have are 23.XXX fps NTSC. If I 2 were to make a VCD out [for example] from this file.. using say TMPGENC.. do I need to maintain it at 23.97 fps or deinterlace it, interlace it.. can some explain this thingy to me ? Thanks...... from memphis tn

[Macros746]

Actually the frame rate has nothing to do with interlace/deinterlace. Interlace/Deinterlace has to do with whether or not the .avi in question was captured from Television. Broadcast television projects 'half frames' each second that the television is on (so basically half the lines on the television) whereas on computer when playing a DVD each frame is a whole picture. This is called a 'progressive' image. Interlacing can be very noticable when you are watching a captured TV show on your computer (so watching an interlaced image on your progressive monitor) especially during action sequences. So the questions you want to ask yourself about interlacing/deinterlacing is this: Are you going to watch the captured TV show primarily on the Television? If so, then deinterlacing is just a waste of time because it is going to be reinterlaced when it is projected on your TV anyway (unless you have a very high end progressive TV) If however, you are going to watch captured TV shows primarily on your Computer, then Deinterlacing in VirtualDub is probably worth your time. If you aren't capturing from the TV at all this is all probably a waste of your time. The whole NTSC film thing is a different can of worms. Some believe that if you are taking a progressive source that was taken from film such as a DVD, that encoding to 23.97 fps (what they would play it at in the theatre) provides a smoother picture quality. Others say that it makes no difference and occasionally causes problems (though I haven't run across any) and you should simply encode ntsc videos to the TMPGenc ntsc template. That is going to have to be a personal choice for you. I recommend you encode a few short samples and see which you prefer. I hope this has answered some of your questions.

Macros

[cuervo]

i'm not sure what 23.97 fps is. I do know that 24fps is the standard frame rate for the film NTSC standard, as opposed to the TV NTSC standard , which is 29.97fps. The frame rate has absolutely nothing to do with whether it's interlaced or not. For a good paper on interlacing go to:
http://www.geocities.com/lukesvideo/interlacing.html
Interlaced video is meant for viewing on a TV monitor and looks like crap on a computer monitor. Conversely, de-interlaced video is meant for final viewing on a digital or computer monitor.
Hope this helps.

[tacosalad]

The decision to deinterlace or not is pretty subjective, but there are some rules of thumb. If your recording is 240 or 288 lines (like 320x240 or 352x28 then it probably isn't interlaced. There are rare exceptions, usually because the video was badly prepared.

But the best test is a visual one; step through a dozen or so frames where there's a lot of motion. If the video is interlaced you'll see thin horizontal stripes around moving objects.

As to 23.976 fps, it's a film frame rate that's designed to convert easily to 29.97 during playback or transmission. Telecine machines are often designed to play film 24 fps movies at 23.976 fps for conversion to NTSC. Trivia: the exact values are (24 / 1.001) and (30 / 1.001), respectively.

-tacosalad