BD3D2MK3D: Convert 3D BDs or MKV to 3D SBS, TAB or FS MKV - Support thread

[r0lZ]

Well, BD3D2MK3D doesn't change the frame rate of the original BD3D. As far as I know, all 3DBD are encoded at 23.976 fps (More precisely, at 24/1.001 fps. Don't ask me why that crazy NTSC frame rate has been adopted when the frame rate of the cinema has always been 24 fps and all modern equipments are able to play exactly 24 fps. It's a stupid american decision imposed to the whole world! Anyway, the fact is that we must live with 23.976 fps.) Of course, in frame sequential frame packing mode, there is twice the number of frames but when distributed to the two eyes, the frame rate is still 23.976.

Unfortunately, there is no support to change the frame rate in BD3D2MK3D. However, it is easy to modify the frame rate of the video stream by editing the text files produced by BD3D2MK3D before launching the encoding. The problem will be that the audio track will not be in sync any more. You will have te re-encode tha audio to adapt its frame rate. You can do that with eac3to (distributed with BD3D2MK3D, in its toolset folder) but wou will have to write the command in the Windows command prompt yourself. See here for more info. You will also have to change the file name in a text file.

In summary, you can select the Full-TAB mode in BD3D2MK3D, then edit __ENCODE_3D.cmd to change the --fps 24000/1001 to - - fps 24
At this point, you can launch the encoding. During the encoding, you should launch the eac3to commands to convert the audio strean(s), with something like this :

"path\to\BD3D2MK3D\toolset\eac3to.exe" "path\to\projects\movie\00001\InputAudio.ac3" "path\to\projects\movie\00001\OutputAudio.ac3" -changeTo24.000 -progressnumbers

Then, edit __MUX_3D_OPTIONS.json to change the frame rate below "--default-duration", from "0:24000/1001p", to "0:24p",
In the same file, change the file name of all audio track(s) at the end of each sections under // ### Audio stream(s)
If the muxing operation took place before you have finished everything, just relaunch the __MUX_3D.cmd file.

I have not explained what to do if you need to include subtitle streams in the final MKV. If it's your case, let me know...

Also, I don't know why the specs of your projector doesn't show SBS at 24fps. If it can play TAB at that frame rate, why not SBS? And the labels of the first formats, "(Frame Packing)", do not make sense. Frame packing is the generic name of all methods used to pack the two video streams in a single file, including SBS and TAB. I suppose they mean Frame Sequential. Anyway, a hardware claiming to support 3D video but unable to play the only official frame rate of the 3DBD format is certainly a bizarre hardware. But unfortunately, it's the case of many projectors. BTW, can I know if you live in NTSC or PAL land?

Sorry, I can' t help much more.

[r0lZ]

I forgot to explain that it is theoretically possible to avoid the audio re-encoding by just editing the mux options json file. But the result may not be perfect. I can explain how to do it if you want to try. That will be much easier and quicker. (The conversion of the subtitles to 24fps use the same method).

[VonHagenstein]

Allrightythen... First, I'm very grateful this forum exists, and for the creator of BD3D2MK3D. Wealth of info here. I'm still a relative noob at using it but not a complete noob to the world of working with video and audio, encoding etc. in general. Hopefully I'm following proper protocol with this post; if not someone set me straight.

I have a decently sizable collection of 3D Blu Rays that I am just getting ready to embark on ripping. Over 300. Yeah, I'll be at this awhile.
I'm currently using BD3D2MK3D to convert MVC 3D mkv files sourced from my 3D Blu Rays to Full SBS/TAB format.
Using FSBS as an example, this results in a 3840 x 1080 frame containing the full-res left and right eye images side-by-side.

What I want to end up with is a 3840 x 2160 frame with that same content. For FSBS this means the image would be stretched vertically from 1080p to 2160p. For FTAB it would mean stretching the images horizontally from 1920 to 3840.
I could take the resulting output file from BD3D2MK3D and load it into something else, stretch it, then re-encode it. That whole copy-of-a-copy/re-encoded-multiple-times thing with all the horrible generational quality loss it brings. Which leads me to question 1:

Q1: Is there an "Additional options:" command(s) I can add, or via other means, get BD3D2MK3D to output FSBS or FTAB stretched into a 3840 x 2160 frame, as opposed to the 3840 x 1080 / 1920 x 2160 frames I currently get? So that I can get files in the format I want in mostly one step instead of multiple, avoiding the pain and quality loss of having to re-encode multiple times?

Next questions are to help me understand all of this better.
Q2: Am I correct in thinking that BD3D2MK3D drives AVISynth for the (re)encoding portion, and that AVISynth in turn uses whatever it's configured to use (ffmpeg etc.) to do the actual encoding, or BD3D2MK3D is driving ffmpeg directly or...?

Q3: Looking at the [?] help for the "Additional options:" section on the [5: Options and Go!] tab of BD3D2MK3D leads me to think that the commands/parameters/switches entered there are related strictly to the encoding portion of the process, is that correct? If so, I'm thinking that's not going to be a path to what I'm trying to do (just a means to fine-tune the encoding process with advanced options etc.)?

Q4: If AVISynth is being driven "behind-the-scenes" so-to-speak by BD3D2MK3D, is there a way to "inject" or utilize additional AVISynth commands or functions into the process? Such as stretching, sharpening, other video-processing things etc. AVISynth is a deep tool in and of itself, and I haven't learned it yet, but surely it has features that would let me stretch my video to the desired height/width? I'm not sure where I would (if possible) utilize those commands with BD3D2MK3D, or whether any syntax would need to be modified for them.

I learn best by examples, so if anyone wants to point me to those or sources of info on the topics I'm happy to look at those. I've done a LOT of searching for these answers already but my Search-Fu has failed me thus far.
Appreciate any help.

[r0lZ]

Hello and thanks for your appreciation of BD3D2MK3D.

First, I would like to know why you want that strange output format, stretched in one direction but not both. With Full-SBS (or Full-TAB) option, you get a full-HD video. The horizontal resolution is due to the two views stacked together, hence its value identical to the horizontal size of an Ultra-HD 2D video. But it's not UHD! Resizing the height as you suggests means that you will obtain an hybrid mix between full and ultra HD. As far as I know, it's a format not supported by any hardware player, and even probably illegal. Note also that enlarging the video will not improve the overall video quality and may even degrade it somewhat.

Anyway, yes, it is possible to resize the video as you want it, although not with the GUI (because you are almost certainly the only person who wants that!) You are right about the way BD3D2MK3D uses avisynth internally. And avisynth itself uses several extensions to decode the source AVC video and to "hardcode" the subtitles over the video (if you have enabled that option). It doesn't use ffmpeg directly although some avisynth plugins are derived from ffmpeg (but BD3D2MK3D doesn't use them).

The avisynth magic is controlled by the __ENCODE_3D_MOVIE.avs script. It is generated by BD3D2MK3D with the commands necessary to decode the two video views, stretch them in one size if you have selected the Half-SBS/TAB option, optionally hardcode the subtitles and stack the two views together in SBS or TAB format. The resulting output is then sent to the x264 or x265 encoder. When the project is generated by BD3D2MK3D, the encoding is not launched automatically by default to let the user modify the content of the AVS script. It's why you can easily change the final resolution, without the necessity to encode the movie twice.

So, when the project is generated, edit __ENCODE_3D_MOVIE.avs with a text editor. In Full-SBS/TAB, you will notice that two lines (Even and Odd can be swapped, depending of the input format of the BD3D):

left  = SelectEven(interleaved)
right = SelectOdd(interleaved)

It's where the output generated by the MVC decoder is processed to isolate the two views. And, after that step, you can add any filter to modify the video. I assumes that you want a Full-SBS output resized vertically to obtain the hybrid output described above. You can simply add these two lines right atter the two lines above.

left  = LanczosResize (left, 1080, 2160)
right = LanczosResize (right, 1080, 2160)

Here, you have created that strange mixed format. Of course, the horizontal width is not modified, since the two images are still not stacked horizontally together. This will be accomplished later with the "StackHorizontal(Left, Right)" command, and after that command, you will obtain your 3840 x 2160 resolution. See here for the various resize filters available natively with avisynth.

Now, that modification is not sufficient to ensure a correct output by the player. You should also modify the values of the aspect ratios, so that the player will be informed that the format it has to play is not at all usual. Therefore, edit __ENCODE_3D.cmd to modify the sample aspect ratio included in the encoding command. In the normal Full-SBS format, the SAR should be 1:1, but it is probably 1:2 (or the opposite - honestly, I'm not sure). So, change --sar 1:1 to --sar 1:2.

Edit also the --aspect-ratio value in the __MUX_3D_OPTIONS.json file. In the // ### 3D video stream section, locate this:

	"--aspect-ratio",
	"0:32/9",

and change it to whatever your player may need to stretch the picture during the playback and obtain the correct display. This may be, for example:

	"--aspect-ratio",
	"0:16/9",

Or, maybe "0:16/18". Again, when playing with non-standard format, the correct aspect ratio values are difficult to determine, as they will depend of the interpretation by the player.
BTW, even in standsrd Full-SBS, the SAR and aspect ratios depend of the player. It's why there is a BD3D2MK3D option to modify them according to what your player needs. See Settings -> Full-SBS/T&B aspect ratio. With some luck, the aspect ratio values necessary to play your stretched video will be available via that menu, and you will not need to edit the two files to modify them.

I think I have replied to your Q1 and Q2 questions. For Q3, yes, the last tab deals mainly with the encoding options. You can perhaps replace the procedure described above with a resize option included in the Additional options field of the x264 parameters, like this:

--vf resize:3840,2160,method=lanczos

It's clearly easier (especially since you can save that option for later with Settings -> Save Tab Settings now), but personally I would prefer to do the resize operation with avisynth. And you will probably have to modify the aspect ratio values anyway.

For Q4, you know now how you can modify the avisynth script to include new commands. I have explained it for the resize, but you can add other commands as well. Just take in mind that the two views must be (almost) identical, as otherwise the effect on your eyes can be disastrous, so use only commands that will act on both views in a very similar way.

Good luck !

[VonHagenstein]

Thanks so much r0lZ for replying and for continued support of the tool. Stuff like that tends to be thankless job.
I kept digging after posting and was getting pretty close, but this should get me over the finish line.
I'm going to do a deep-dive soon to learn avisynth because I think that can only benefit me for other uses too.
As for the "Why" of this odd sounding format lol, I'll do my best to explain.
It's a "2 birds one stone" solution for my scenario. Maybe even 3 birds lol. And I'm overly-verbose, not on purpose, I just am for some reason, so I apologize in advance for that.

tldr; There are 2 types of displays I primarily view these files on: A VR headset and a large passive 3D television (approx. 85"). This "odd" format is the one I can most easily and universally use on both my VR headset and my 4K passive-3D TV via a media-server due to limitations my TV has on the type of formats for 3D content it can process. Doing it this way also allows for a single movie file I can view on both devices either directly (e.g. a computer connected to my TV via HDMI, or a file saved on the VR headset's storage) or via streaming from a media server, with no resolution loss and as little quality loss as possible other than what might occur due to compression etc.
Gory details follow...

As you already know, 3D Blu Rays normally contain frame-packed video with a separate 1920x1080 frame for each eye. If I take each of those 1920x1080 frames and "squeeze" them into an output video that is also 1920x1080 via the "Half" options, I am losing either half the horizontal resolution of each frame, or the vertical resolution, depending on whether I'm doing SBS or TAB. Which again, you're already aware of. Enter the "Full" options. Those do solve the resolution loss issues by stacking the full resolution frames next to each other, either horizontally or vertically to produce either a 3840x1080 or 1920x2160 video containing both the left and right eye images. Sorry again for "I'll take things I already know for $200 Alex..."

So the 3840x1080 or 1920x2160 frame sizes can work fine in my VR headsets. I have a variety of VR media "players" for those, the main one being "Bigscreen", which can simulate watching a movie in a theater with a large screen. It's quite convincing and I enjoy using it a lot. H-SBS, H-TAB, F-SBS, F-TAB, and even interleaved are all supported. So the regular presets in BD3D2MK3D do work just fine for that. For my LG 3DTV however things are more limited, unless I jump through some hoops.

Re. the 3DTV. It's a 4K passive display. 2D content can display at full 4K res with HDR. 3D content however is interlaced/interleaved with alternating rows of pixels for each eye. A polarized layer with rows of alternating polarization direction lets me use modern movie theater style 3D glasses that don't require batteries like active-3D (frame-sequential) displays use for viewing 3D content. The interleaved nature though means that, regardless of the display being 4K, the maximum vertical resolution ever available to me in 3D is going to be 1080p, although the horizontal resolution can still be 3840 (the display also supports the full 4096 spec.).

For 3D formats going into the TV, it can process frame-packed, H-SBS, H-TAB, or interlaced. Interlaced is problematic with it; it displays it, but there's some sort of processing that occurs and I've never gotten interlaced 3D content to line up 100% with the polarized lines such that no ghosting occurs. All other 3D formats are processed into the interleaved format by the TV itself for passive-3D-glasses viewing.

Formats that the TV cannot natively process however include F-HBS, F-TAB files, and frame-sequential. I wish it could. It would simplify things for me. I have to provide either 1920x1080 or 3840x2160 video (or frame-packed). With 1920p I'm going to lose either half the horizontal or half the vertical resolution of the image, since both the left and right eye images have to be "squeezed" into the image. With a 3840x2160 frame I can put both the right and left eye images into that with no resolution loss. But to accomplish that I have to provide a 3840x2160 frame to house the left and right eye images. As long as the full-res images are being stacked I don't lose any resolution but I still need to stretch or upscale them in the appropriate direction so that the fill the frame. My TV will not do that for me unfortunately, nor will it properly process a F-SBS/F-TAB 3840x1080 or 1920x2160 frame.

Using this format also solves another issue for me: Streaming 3D movies to BOTH my VR headset AND my TV without resolution loss.
If I didn't want to use a media server, I could play 3D movies from files on my TV simply by connecting a laptop/computer to it (or my original 3D Blu Rays via my 3D Blu Ray player).
Using Potplayer + "MadVR" and some plugins I can play nearly any format, even ".iso" rips directly. Interlaced and frame-sequential too.
With iso's or mvc-encoded mkv files that software combo can decode the individual left/right eye images into a variety of selectable formats and aspect ratios in real-time and it works great with fantastic visual quality. But I can't stream those formats to my TV with any current media server that I'm aware of. Plus those are quite large files, since they haven't been re-compressed to something more efficient.

Anyhow, I hope all that that explains the "why" part, if you or anyone else is curious. Even if I did use more words than needed to try and do that.
I'm a stereoscopy enthusiast of many years, having done stereo photography, videography, wrote my own anaglyph-conversion process that resulted in better looking color than any commercial processes I've seen, and continue to be interested in things like old stereoscope cards, View-Master reels, and obviously 3D movies lol. Always happy to meet others with similar interests. And there's not many people left still using a 3D TV (although there are still lots of 3D projectors in use). I may indeed be literally the only person that might want to use this formatting for 3D video lol.