Aspect ratios, correct true resolution to crop 1.66:1 DVD's?

[Sesam]

I'm in the process of converting several movies from DVD to MKV (x256+AC3). The goal is to not loose much quality in the process, as these are meant to be for archival.

Using anamorphic encodings, I have cropped movies so far according to the following table:
1.33:1 720 x 480 (4:3)
1.77:1 720 x 480 (16:9)
1.85:1 720 x 464
2.35:1 720 x 368
2.40:1 720 x 352

After much discussion and research I have come to the conclusion that these are the preferred values by purists (opinions?). If this looks reasonable lets move on to the real question.

How much should be cropped from a 1.66:1 anamorphic DVD. These puzzle me because they have black borders on all sides.

The best I have come up with so far is 614x432 (anamorphic). The result looks good, but I still want to know what is considered standard safe cropping for movies of 1.66:1 aspect ratio .

[XrayMind]

Form reading the wikipedia entry, the 1.66:1 is only use in some European countries. Is pretty confusion even reading the wikipedia entry. But looking at most rips of movie DVD , the resolutions are 640x356(1.8:1, close to 16:9[1.78:1] of HDTV) or 640x336(1.9:1, close the 1.85:1 use for 35mm US/UK film releases, or 640x272(2.35:1, close to the 2.39:1 use for 35mm anamorphic Panavision films).

[eye]

How much should be cropped from a 1.66:1 anamorphic DVD. These puzzle me because they have black borders on all sides.

Just crop the borders and ignore the display aspect ratio.

As long as you don't scale the image, the pixel aspect ratio remains constant. There are only four pixel aspect ratios defined in the DVD video standard (see http://en.wikipedia.org/wiki/Pixel_aspe ... eo_Formats):

10:11 = standard NTSC
40:33 = widescreen NTSC
12:11 = standard PAL
16:11 = widescreen PAL

After cropping the image, you can use these values to calculate the new display width and height. Here's an example:

original image dimensions: 720x576 (widescreen PAL)
cropped image dimensions: 704x432
new display width: 704 x 16:11 = 1024

When encoding this video, there are two things to do:

- specify a display width/height of 1024x432 in the MKV header.
- specify a custom sample aspect ratio of 16:11 in the x264 codec settings.

Storing the sample aspect ratio in the H.264 bitstream may seem redundant, but it will become useful later if you remux the bitstream into a different container (e.g. MP4).

[Sesam]

Thanks for the advice you two , aspect ratios always manage to confuse me .

Yea I realized that my original plan was flawed anyway, as the full 720 width is not usually used (there appears to be a few pixels of black or garbage on the sides on DVD's). So for a typical NTSC widescreen movie I'm going to crop 8 pixels from each side (so the video is 704x464, and then anamorphically stretched out to right proportions).

This way the end results should be rather good x).

Anyway to make my life easier I have resorted to ripping with Nero Recode. It saves me lots of steps and guesswork . The aspect ratios are always correct, subtitles ripped to vobsubs, chapters added, and it correctly detects frame rate and interlacing. All I then have to do is to convert to MKV container, and add srt/ass subs