[r0lZ]

Not hard. Nearly impossible.

The 3D blu-ray frame rate is 23.976 fps. Dot. If DLP projectors cannot support that frame rate, that means that they cannot show the output of blu-ray 3D players, and "3D ready" is obviously a lie.

You can try to remux the streams at 24 fps (for a total frame rate of 48 fps) or 30 fps (total 60). The sound will not be in sync, but at least you will be able to test if the 3D MKV files are really supported.

To do that, simply edit _MUX_3D_OPTIONS.txt, and change --default-duration 0:48000/1001p to 0:48 (or 0:60) in the 3D video stream section. Then launch _MUX_3D.cmd to create the MKV file at the specified (wrong) frame rate.

If that works, you can manually re-encode the audio files for 24fps and remux again (at 48 fps instead of 47.952). With some luck, you'll be able to see the movie with properly synced audio. (I don't know what is the best free way to convert the audio rate. I use Adobe Audacity for that kind of jobs, but it is not free. You may probably use eac3to, with one of its GUIs.)

Converting to 60fps is much more complicated. That requires to apply pulldown (or telecine) to the video stream. In other words, you must convert a movie shot for the cinema to the old NTSC format, but not exactly because 30 (or 60) fps is not the standard NTSC frame rate. That's really strange, since all 3D movies of all times have been shot for the cinema at 24 fps, and as far as I know, never for the NTSC TV. Anyway, although you can try to do the pulldown conversion, that will be slow and introduce many artefacts, and I can't guarantee that the 3D effect will be preserved. However, if you really want to do that, you will have to edit the AVS script to convert the two views. I can explain how to do that later, but do simple tests first.

In all cases, you will need to convert the subtitles files as well, and you'll lose the chapter points.

BD3D2MK3D can't output in 24 or 30 fps, and I will certainly not implement that. It converts a BD3D to MKV, and doesn't invent fancy frame rates, because some hardware players or projectors cannot play the standard 3D frame rate. Sorry.

[EDIT] The tutorial to convert video to 60fps (pointed to by your last link) is not at all what you need. It explains how to convert a 2D video at 24fps to 48fps to improve the quality and avoid flickering. You need to convert TWO video streams at 23.976 to 24 (or 30) fps each, and that gives a total of 48 (or 60) fps. And for 24 fps, there is no need to encode the video again. The change in speed is small enough. You can simply change the frame rate info when you mux the file. The problem is that small speed change is sufficient to create progressively a de-synchronisation with the audio. Therefore, you must re-encode the audio, not the video. As explained above, unfortunately converting from 23.976 to 30 fps is very different, and you cannot just change the frame rate, because your movie will play too fast, like the very old b&w films. I can only hope that your hardware supports 24 fps. 30 fps is a total nonsense in the 3D world.

Another thing. Some peoples convert a 3D movie taken from a BD3D (always at 23.976 fps) to 25p, because 25 fps is the PAL frame rate, and therefore it is possible to use the audio from a PAL DVD with the video of the 3DBD. That's really easy (if you don't need the chapters and subtitles). It is sufficient to use the frame rate 25 instead of 24000/1001 in the mux options, and to replace the original audio track with the audio of the DVD. But that's 25 fps, not 24 or 30. And NTSC DVDs are at 29.97 fps, not 30. And since the speed change is too important, you cannot simply change the frame rate value. You must telecine and re-encode the video stream.