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Old 20 Oct 2002, 07:51 AM   #1
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Wink-2 Lending a helping hand

Hi to everybody,

In all the downloadsections, magazine-articles, manuals on how to... etc. things can get quite complicated (f.i. nandub) with all kinds of parameters, switches, bitrates and more that you can set to get the best result when making that backup of your dvd.
Why make it so difficult? I have converted some movies to the divx 3.11 alpha in a quality equal to that of the original dvd and without all those bitrate-calculations etc. etc. etc....
So I thought, let me share my experiences with the rest of the community. I will try to sum up how I did it.

First of all you got to rip the movie to your harddisk, thats where it all starts.
Then use DVD2AVI and VFAPICONV to make a projectfile.
Next we will use Virtualdub with some filters for the video to compress it into divx low-motion.
The sound is compresssed into mp3 (96kbit) stereo and Voila, there you have it.


The clue lies in the use of the filters. Especially the general convolution filter. Using this filter can reduce the filesize up to 40%, depending on how strong you make the settings.

When You convert the movie try the following setup:

The first filter: Resize filter
Resize the video to 640x360 expand it to 640x480. This will give you the widescreen-format with the black area's above and below the movie. I keep the black area's since most of the films will be viewed on a 4x3 monitor-screen.
The black area below the movie is also usefull for placing the subtitles. I hate it when they are in the movie itself.


The second filter: Brightness/Contrast filter
Increase the brightness by 3%. This is done because, when viewing a movie on a monitor the image tends to be a bit darker. Another bonus is the fact, that a brighter image compresses a litlle bit better.


The third filter: General convolution filter
Now this is where our general convolution filter comes in. This filter blends a pixel on the screen depending on it's own value and that of the surrounding pixels. It is set up in a matrix of 3x3. This gives you 9 values that have to total 256.

f.e.

12 12 12
12 160 12
12 12 12


You cannot use just any values. If you use the wrong values, the image will show coloring-errors.
Good commbinations are:
208 for the center-value, 8 for the surrounding.
160 for the center-value, 12 for the surrounding.
128 for the center-value, 16 for the surrounding.
96 for the center-value, 20 for the surrounding.
64 for the center-value, 24 for the surrounding.

The lower the centre-value the higher the compression will be, but als the higher the blurring of the image will be.

A setting of 16 by 128 or 12 by 160 gives good compression without apparent loss of quality.

The fourth and last filter: Vobsub
Vobsub to put in the subtitles. I put them in the bottom black area, so that they are not in movie itself.


That's it, except for the bitrate. I would recommend divx-lowmotion, a key-frame every second, crispness at 80% and a bitrate of 3600 or higher. For a 100 minute-movie you will get a filesize somewhere between 600Mb and 1400Mb.
Using virtual-dub you can then split the file and burn it on 2 cd's.
(Using these settings with a general convolution of 16 by 128 compressed "The Others" to a mere 671Mb)

note: when compressing the audio it is a good idea to increase the volume to a 115%, since some of the dynamic is loat in the compression to mp3.


If you get a filesize that is higher than 1400Mb there are a number of options you can try to reduce the filesize.
1: reduce the audio to 48kbits mp-3stereo (you want here the difference)
2: resize to 512x288 expanded to 512x384.
3: increase the settings for the general convolution.
4: recompress the end-credits with divx fast-motion key frame every 3 seconds and bitrate 600. This can reduce the end-credits to 20% of its original size. Considering that end-credits can take up to 120Mb, you can gain a lot here.


That's really it.

I hope some of you find the information usefull and timesaving.


sincerely yours

Farscape
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Old 20 Oct 2002, 09:05 AM   #2
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Thanks for the tips, Farscape. I'll have a look into that General Convolution filter. It may just help me for a movie I'm having trouble compressing.

However, I find it hard to agree with you on the statement that you can get the same quality as the DVD, especially after you described your chosen method for compression. For one, 96 kbps MP3 is not 'quality' at all. Using ultra high bitrate (3600!!!) DivX does give you really good quality, without the need for doing 2-pass conversion. However, it defeats the purpose of doing DivX, which is to compress as much as possible without much loss of quality. I'd rather keep a 100 min movie in one CD, rather than 2 as a 3600kbps movie is bound to give.

Thanks for the tips again anyway. Your effort is well-appreciated.
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Old 20 Oct 2002, 07:50 PM   #3
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defenetly, most appreciated.

BTW - Enchanter, how are you doing? long time no c!
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Old 20 Oct 2002, 10:29 PM   #4
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As fine as always, though busier than usual.
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Old 20 Oct 2002, 10:31 PM   #5
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o right..in that sense lol....

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