PAL -> NTSC questions

[dg_phillips]

Some basic Conversion 101 questions I have here:

1. In ALL the guides and instructions when converting PAL to NTSC we must invariably demultiplex the audio and video. When I use a tool like BeSweet to convert the audio from 25.000 fps to 23.976 fps, at the very end a page is displayed by BeSweet that has imbedded in it the fact that the audio conversion included a frame rate conversion from 25 fps to 23.976 fps. Now in ALL the guides and instructions, the next step is usually converting the video with TMPGEnc...great, this stuff seems to make sense up until here. Now we check one box on the Advanced tab in TMPGEnc that says "Do not frame rate conversion" (bad English)...now it seems to me that logically following these instructions would put me really out of sync...ie audio - frame rate converted already...video - DO NOT FRAME RATE CONVERT...why would we frame rate convert one but not the other???

2. VIRTUALDUB guru needed here...I have started with a PAL MPEG-1 episode of my television series...I, then, seperated the audio and video with TMPGEnc to produce both a .mp2 and a .m1v. I have tried to frame rate convert the video with VIRTUALDUB following the instructions under FRAMERATE CONVERSION - Section 1c. FRAMESERVE WITH VIRTUALDUB and when I Start the Frameserver...it does absolutely nothing but just sit there...why is this? Am I missing a plugin from VIRTUALDUB? Does VIRTUALDUB not handle MPEG-1? I have tried with both the original .mpg AND the .m1v and in both cases, VIRTUALDUB just sits there and does nothing. What am I missing here?

Dan Phillips

[bugster]

I will try and answer your two quastions.

1. If you provide TmpGenc with a (for instance) 25fps video source and tell it to encode at 23.97fps, it will attempt to ensure that the resulting movie is the same length as the original. It does this by removing frames (or duplicating frames in the reverse case). This will result in slightly jerky playback. When you tick the box 'do not framerate convert', TmpGenc will not do this. It will instead treat the source video as if its framerate was that which you require. So the video will be slightly longer (or shorter in the reverse case) but playback will be smooth. Its a matter of what anyone person means by 'framerate conversion'. In this case I agree that it is confusing.

2. I have never frameserved mpeg with vdub, but what normally happens is that you get a small dialog box with, amonst other inf, something liek 'Number of AV requests'. You should also have craeted a .vdr file. OPen this .vdr (or .vdr.avi if you want to call it that) with your favourite encoder (Tmpgenc?) and when you start encoding, this number will increase for each frame 'served' from vdub.

Hope this helps.

[dg_phillips]

Bugster:

Oh, I think I am understanding you to say that VIRTUALDUB is waiting for me to start TMPGEnc and access the two placeholder files he (VIRTUALDUB) has created to actually start the frameserving...this would totally explain why it just sits there...okay then...I will proceed accordingly...thanks, Bugster...

Dan Phillips