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  1. hi i have been banging my head on my desk all day

    working on xvid file that gspot reports as being 25 FPS and audio at 48000Hz CBR. after extracting the audio and getting ready to convert.... CCE says the file time length for video is 45.01 min @ 29.97 FPS whereas the audio remains at the correct time of 54.02 min. synch probs galore..so i used goldwave to time warp the audio, now i get perfect synch but the audio is now at alvin and the chipminks range of sound.

    what can i do to remedy this problem?
    thanks

    edit: would running CCE at the same framerate as the file then authoring it in tmpgenc dvd author remedy this for compliant NTSC dvd?
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  2. Member Krispy Kritter's Avatar
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    why are you converting from 25fps to 29.97fps? NTSC is 23.976fps.

    There is more info in the HOW TO / CONVERT section. Look for PAL to NTSC conversion guides.
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  3. from this site

    NTSC (NTSC Film)
    Video:
    Up to 9.8 Mbps* (9800 kbps*) MPEG2 video
    Up to 1.856 Mbps (1856 kbps) MPEG1 video
    720 x 480 pixels MPEG2 (Called Full-D1)
    704 x 480 pixels MPEG2
    352 x 480 pixels MPEG2 (Called Half-D1, same as the CVD Standard)
    352 x 240 pixels MPEG2
    352 x 240 pixels MPEG1 (Same as the VCD Standard)
    29,97 fps*
    23,976 fps with 3:2 pulldown = 29,97 playback fps (NTSC Film, this is only supported by MPEG2 video)
    16:9 Anamorphic (only supported by 720x480)
    what difference in quality is there between 29,97fps and 23.976fps?
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  4. Standard definition NTSC TV always runs at 59.94 fields per second. Anything that feeds it must provide that signal. You never actually see a full frame on TV. By the time a field is being drawn the previous field has faded away.

    Film normally runs at 24 frames per second. When it is broadcast on TV it is slowed down to 23.976 frames per second. The frames are then sent to the TV one field at a time as the TV expects them. Half film frames are sent as two fields, half are sent as three fields (one field is sent twice). On average each film frame becomes 2.5 fields. 23.976 * 2.5 = 59.94. This introduces a very fast jerkiness which most people don't notice.

    film frames: 1 2 3 4 5 6...
    video fields: 1t 1b 2t 2b 2t 3b 3t 4b 4t 4b 5t 5b...

    (t = top field, b = bottom field, NTSC TV always alternates between top and bottom fields.)

    DVDs can contain the video with progressive frames at 23.976 frames per second. Then the DVD player will perfrom the 3:2 pulldown to make 59.94 fields per second for the TV.

    Alternately, the 3:2 pulldown can be performed prior to creating the MPEG/VOB file for the DVD. This will result in a 29.97 frame per second video. Each video frame contains two video fields that the DVD player sends to the TV one field at a time. Using the example above the fields are packed in frames as follows:

    video frames: (1t+1b) (2t+2b) (2t+3b) (3t+4b) (4t+4b) (5t+5b)...

    The simplest way to convert 25 fps material to 23.976 fps is simply to throw away 1 out of every 25 frames (with the occasional addition dropped frame to go from 24 to 23.976). This leads to a slightly jerky result -- one little jerk every second. This is what a lot of software does.

    The best way to convert 25 frame per second material to NTSC is to slow it down to 23.976 frames per second progressive MPEG2/VOB and let the DVD player perform the 3:2 pulldown. This will leave you with audio that's out of sync unless you compensate for the slower frame rate.

    There is a third method which uses a different pulldown pattern (3:2:3:2:2) to create 59.94 fields per second directly from 25 progressive frames per second. The benefit is that you don't have to adjust the audio. Look into DGPulldown if you want to consider this.
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  5. WOW thats the most in-depth answer i have ever gotten...anywhere. thanks i understand what you are saying as i use CCE and see the dropdown you are speaking of.

    in VSO DivxtoDvd, when it sees a framerate of 25 it automatically calls it PAL, so you can understand my confusion. playing with settings and some freeware apps i am able to keep video in synch now.
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  6. Member Krispy Kritter's Avatar
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    good job junkmalle...damn, even I understand it now. : )
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  7. I'm glad you guys found my post useful. I tried to include enough information to get the principles across, but not so much as to overwhelm you!
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