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Old 30th September 2002, 23:16   #1  |  Link
ripsaw8080
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Converting to MPEG-4 from a problematic DVD source

I have recently set about trying to encode a movie from DVD onto 1 CD that has proven to be more difficult than I imagined. Chinese Ghost Story, a classic of HK cinema, on an NTSC DVD from Media Asia. After some inspection, it seems to be pure NTSC video material, all frames interlaced. I attempted to determine if there was a way to recover film frames, but in examining the individual fields there is a heavy motion blur there, suggesting the original video was field-blurred even before being converted to NTSC! Anyone seen this kind of thing before? Well, it seems I'm not going to be able to obtain original film frames; and at ~1.5 hours long, leaving the frame rate at 30fps with 25% more frames than I usually encode with, and strongly motion-blurred frames with not even clean scene changes (they're blurred, too), and the video isn't very clean even when there isn't a lot of motion... I'm finding it difficult to encode this onto one CD with a decent resolution. I've already gone with an Ogg soundtrack to conserve as much data for the video as possible. So far, Divx 5 seems to be able to compress it better than XviD, I guess because of its tendency to smooth-out some finer details. Anyone know of any tricks I could employ to make something like this compress better?
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Old 1st October 2002, 02:38   #2  |  Link
midiguy
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perhaps try the convolution3d filter for avisynth, with low settings?
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Old 1st October 2002, 03:09   #3  |  Link
manono
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Hi and welcome to the forums-

Don't you just love Media Asia for wrecking a perfectly good movie (and there are many more like that)? I decided that it was impossible to do for 1 CD without taking the resolution lower than I was willing to go. So I did it for 2 CDs at 608x304 with VBR 192 MP3 audio using XviD. DivX5 is a good way to do it though, because of the greater compressibility afforded by B-Frames.

It's interlaced, comes from a badly scratched source, and they cheated on the bit rate by keeping it a single layered DVD. A very difficult movie to compress. You have to keep it at 29.97fps and choose your deinterlacer of choice. I think I may have smoothed it a bit to help with the compressibility and the appearance, but I can't really remember (and midiguy's suggestion about using C3D is a good one). Also, the subs are atrocious, and I cleaned them up a bit. If you'd like them, I'd be happy to pass them to you. Too bad though, since it's a very fine movie.
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Old 1st October 2002, 05:11   #4  |  Link
midiguy
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also, external subs. subtitles burned in the video stream can really hurt compressibility. use external subs!
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Old 1st October 2002, 05:39   #5  |  Link
ripsaw8080
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Yep, 608x304 is what I've been trying to work with, as anything smaller seems sub-par. I could do a crop-after-resize 640x320, but I decided I had to crop off the nasty edges that just consume bitrate while looking ugly. If I resigned myself to using 2 CDs, I wouldn't have any trouble, of course.

I thought about using C3D, but came across a dilema: decomb.dll's FieldDeinterlace(), even with blend=true, leaves a great many artifacted lines in the result, so I've been using VDub's deinterlace:blend filter, which takes out all the lines and leaves no artifacts (and also does a very gentle smoothing which helps compression, I think)... and I really need to run C3D *after* the deinterlacing, and as an avisynth plugin I can only run it *before*. Too bad there isn't a .vdf version of it. Oh well, it seriously increases my processing time, anyway.

Thanks for the offer of your cleaned-up english subs; I thought about making the really obvious repairs to spelling and grammar, but I'm going to leave them as they were on the DVD. They're so bad, they're funny in places... what www.hkflix.com calls "flubtitles"

Thanks for your help, guys.
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Old 1st October 2002, 05:58   #6  |  Link
manono
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Hi-

I can't remember what I used for Deinterlace settings, but if FieldDeinterlace() isn't doing it for you, then try and tighten up the comb detection, like maybe:

FieldDeinterlace(Threshold=10,Dthreshold=5)
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