DVD2SVCD - CCE luminance level adjustment

[mdavis]

Does anyone know how to set up DVD2SVCD such that it will use a luminance level of 16 to 235 with CCE?

From what I can tell the CCE control file is changed to set the levels as 0 to 255. This results in too dark a picture in some areas and too bright in others. I suppose one way around this problem may be to preprocess in avisynth, but I have yet to find a function that would compress the luminance range.

Thanks

[DJRumpy]

There isn't a setting for it in DVD2SVCD. I stopped using it too long ago. It breaks to easily.

Use AVISynth. You'll get it done faster, better, and with fewer problems.

In DVD2AVI ensure you have TV SCALE selected under
Video | YUV->RGB
This will fix your luma scale in the output.

The AVISynth command that you might also find useful is called LEVELS

(from the AVISynth docs)

Levels(clip, int input_low, float gamma, int input_high, int output_low, int output_high)

The Levels filter adjusts brightness, contrast, and gamma. The input_low and input_high parameters determine what input pixel values are treated as pure black and pure white; the output_low and output_high parameters determine the output values corresponding to black and white; and the gamma parameter controls the degree of nonlinearity in the conversion. To be precise, the conversion function is:

output = [(input - input_low) / (input_high - input_low)]1/gamma (output_high - output_low) + output_low

[adam]

You want a luminance level of 0-255. This is the correct scale for television and should be what your source has. If your source is DVD and properly handled then there is no reason to use 16-235, which is why DVD2SVCD doesn't even give you the option.

As DJRumpy said, using tv scale in dvd2avi and 0-255 in CCE should give you proper colors on your tv.

As for these color problems you are seeing...Make sure you are only making these evaluations on your tv, not your pc. More than likely this is just a problem with your dvd player, its actually quite common. If you want to ensure that you are using the right luminance level then make a test clip using a widescreen source Don't crop but add borders, but make the borders less than the black bars so that you see some of your borders you added and some of the ones that were existing in the movie. If your luminance level is off than the existing border should appear grey compared to your added borders. If its correct than you won't even see where one starts and the other begins.

Unfortunately I'm not sure how to do such a test encode in DVD2SVCD, you may have to do this manually.

[mdavis]

I thought that I had read somewhere that for TV you want 16-235, I probably just got that wrong.

I am doing my evaluations on the computer so maybe that is part of the problem, but in one test I did I took an AVI and converted it with avisynth and CCE using both the 0-255 setting and the 16-235. I noticed that the color levels were identical to the original with the 16-235 setting, but with the 0-255 setting the light yellows looked close to whites and the dark greens were getting close to black. Any ideas as to why the CCE encoding would do this?

DJRumpy, I noticed the levels setting but I am unsure how I would use it to achieve the effect I am looking for. Now that I look at it more closely I suppose that it may give the desired effect.

Thanks

[DJRumpy]

That was my understanding as well. A TV is only capable of displaying 16-235 (luminance), where a PC monitor has 0-255. If you keep you luminance setting in the 15-235 range throughout then entire process, then ideally, you would have no change, or 'squashing' effect to your levels when the finished project is displayed on a TV.

[wulf109]

I would agree with Adam. I've used CCE to transcode many DVd's and I find that the 0-255 range always results in DVD-R looking much closer to the original DVD. Your encodeing from an .avi? It may itself be improperly encoded.

[adam]

Sorry, I got the logic totally backward since I have just been using tv scale in conjuntion with 0-255 in CCE for so long, the result is the same though...

My confusion was because I equated a setting of 0-255 as preserving a source of 0-255, when actually this setting is used to prevent further compression of a 16-235 source.

What I should have said was that the source is 16-235 and that using tv scale keeps it this way. Using 0-255 in CCE prevents further luma compression or the "squasing" effect as DJRumpy describes it. So as long as you use tv scale in dvd2avi and 0-255 in your encoder than you are fine.

[adam]

I found a really good post about this, he seems to explain it pretty thoroughly.

http://forum.doom9.org/showthread.php?s=&threadid=28815&highlight=luminance+illumination

[jeremymiller]

Does the same hold true, if the source is an Avi file captured from cable/satellite TV?

[DJRumpy]

That would depend on your capture hardware/software. I would suggest you capture a sample, and view the histogram in Virtualdub as Adams link suggests.

Very nice find Adam btw...