Hi experts.
I have a questions regarding frame rates. I am very familar with converting DivX and Xvid avi files, with standard frame rates of either 25fps, 23.976fps and 29.97fps to dvd etc using TMPGEnc. Recently I have encountered a couple of DivX avi's with strange frame rates 23.975 and 29.969. Can anyone tell me how I can deal with these? Do I need to speed up the avi file with virtualdub for the video and BeSweet for the audio?
Eagerly waiting for advise.........
Archie
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Think Before You Do It
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I think you should be fine if you encode the avi's "as is" and let TMPGEnc correct the frame rate. More than likely they were encoded with Virtualdub and for some reason the audio was slightly shorter than the video. Vdub usually syncs the video to the audio in these situations. I honestly think your mpegs will turn out fine despite the avi's odd frame rates.
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I found that some versions of DVD2AVI (not 1.76) would give me the video at 23.975 instead of 23.976 which would lead to a few seconds of sync error by the end of a movie. Check the movie to see if it gradually loses sync. If so run it through Vdubmod, direct stream copy both audio and video and under Video -> framerate??? check a box that says something like "sync video to audio stream" (sorry at work so I can't open Vdubmod up to check if this is right)
Then you should be able to use it like normal. -
If the frame rate if off by .001 then you dont need to worry about the files going out of sync,its usually when the framerate is .005 out that you get sync problem,just encode and check near the end of he clip to see if the audio and video matches.What i do is change the framerate in virtualdub to the correct one and save as direct stream and then check.
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This is actually very common. This is a known problem with dvd2avi. DVD2AVI has a bug where it may lose up to a few frames if the source is encoded a certain way. The problem is exasperated by the fact that mpeg2dec (if you are using avisynth) also loses some additional frames when this happens. You can get the full description of the problem here:
http://neuron2.net/fixd2v/decodefix.html
You can get updated versions of both dvd2avi and mpeg2dec which totally fix this problem, but unfortunately there are alot of previous encodes out there which have been affected by this, and which have slightly off framerates.
As others have said its really a very minor issue if you are just re-encoding this to another format. By default, TMPGenc will duplicate frames to account for any fps changes. Since the change is so minute, you will never notice the repeated series of frames. Also since fps is being changed by frame duplication, the runtime remains the same which means the audio will still sync. Just encode it, you should be fine. -
Thanks all I'll give it a try....You have all been very helpfull
ArchieThink Before You Do It
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