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  1. Member
    Join Date: Apr 2014
    Location: Nederland
    Search Comp PM
    hi everyone,

    I'm a real 3d movie fan and I try to have the best quality for movies. I am dutch, so that means i have subtitles under my 3d movies. for that I use stereoscopic player with the FFDShow plugin. I have a 5.1 surround system, so I also really care about good sound. For 3d I use a 1080p 3d lg screen with passive 3d. I notice, when i play half-SBS movies the quality is not as good as a usual 2d 1080p movie. This is because the pixel quality is 960x1080p. but because we have 2 eyes, there have to be 2 images on a 1080p screen, so every horizontal pixel-row is for the left or right eye. this means that each eye gets a video with a 960x540 pixel quality. there are ways to solve this problem. most people use the half-SBS (left first) view as video output. in stereoscopic player you can also chose the "row interlaced (left first)" view. when you play a half-sbs video file, this doesn't help the quality but when you use a full-sbs (3840x1080) the horizontal rows have 1920 pixels in stead of 920 pixels. I compared this and i've run some tests on this, and the difference is really amazing. I think that if decoders start uploading full-sbs in stead of half-SBS (or maybe both) people will notice that they have been watching low quality 3d movies. there aren't many 3d full-sbs movie online right now, but it is still posible to convert AVC 3d bluray rips to full-sbs, because there the left and right image have a 1920x1080 quality. I hope this will convince people for uploading new 3d movie formats.

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  2. This is why Blu-ray use MVC encoding. One stream is encoded as the full 1920x1080 frame, the other only the differences between the left and right frames. Since there is a lot of similarity between the left and right views this takes less biterate than two full frames.
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  3. Member
    Join Date: Apr 2014
    Location: Nederland
    Search Comp PM
    Originally Posted by jagabo View Post
    This is why Blu-ray use MVC encoding. One stream is encoded as the full 1920x1080 frame, the other only the differences between the left and right frames. Since there is a lot of similarity between the left and right views this takes less biterate than two full frames.
    just did some research on MVC. but i don't think that those 3d video files have to be higher than 25mbs. and i'm talking about already encoded video files (around 20gigs), so no direct blu-ray rips.

    thnx for the response, really helpfull!
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  4. Member Cornucopia's Avatar
    Join Date: Oct 2001
    Location: Deep in the Heart of Texas
    Search PM
    I would like to give you some info that might set you straight on a few things.

    There are a number of ways to input & output stereo3d video, but the choice of which to use depends much on what are one's priorities.

    You want to use full SbS (3840x1080) as that standard. That might seem good to YOU right now, but it isn't always good to other elements of the system. Full SbS is:
    #1 Not even close to backward compatible with 2D. Other than SP or via AVISynth processing (or converting it with SMM, NLEs, etc), you cannot filter one view out to see a normal 2D view. Regular player apps will always show it with both images, unless they are already "stereo-aware".
    #2 Way beyond the max resolution that many media apps (encoding, playing, processing) can deal with (1920-2048 is usually the tops). This will change in the future with the transcendence of 4k+ video, but until those are ubiquitous, many apps will be playing catch-up and will remain unable to work with this at all. This includes lots of hardware, too.
    #3 Not efficient, bitwise (always uses 2x the bitrate of its equivalent quality 2D material, known as "simulcast").
    #4 Just trying to view this on a standard monitor is fraught with problems: it is so wide (32:9 or 3.555:1) that it requires zooming out and making the whole thing smaller just to see it - on even the widest of available screens

    If bitrate savings (with equivalent quality, or better quality with equivalent bitrate) was your priority, you should use MVC as storage format. It still provides Full HD quality to both views in 3D, it is backwards compatible with 2D, and it really does save bits: usually ~1.3x-1.6x vs. 2x for "simulcast" formats.
    If backwards-compatibility was your priority, MVC, or dual-mux files (Cineform 3D, SP's StereoWMV, Fuji3D AVIs, my DualMux AVI/QT/MPG) are preferrable, as those remain self-contained (so nothing is ever un-paired) and works (usually automatically) with both standard players (as 2D) or enhanced, stereo-aware players (as 3D).
    If encoding ease (using current 2D encoders) was your priority, you should use regular squeezed SbS or TaB. They work with mod16 and mod4 macroblock size constraints, respectively, and within the already-mentioned max resolution constraints.
    If broadcast versatility was a priority, using the 3DZ format would probably be preferred.

    Notice that in none of those scenarios is FullSbS the 1st choice. Even Full TaB might be preferrable because, since the Horizontal is the resolution that is the main limiting factor in apps, and the great majority of shows are already much wider than tall, a doubling of the vertical proves to still be within the range of many current apps.

    But I'm guessing the main reason YOU use FullSbS is for 4 considerations:
    A) You want to keep Full HD as much as possible
    B) You want to get the best possible outcome on your Passive screen, so you want to send it a full (non-compromized already) resolution horizontal. (This is laudable because the horizontal is the dimension that provides the parallax cues to give you 3D, so the better the H, the better the roundedness & naturality of the depth).
    C) You need something that is easily - and Freely - encodeable & decodeable (which often removes MVC).
    D) You have found out by trial & error that Full SbS gives you a good image (compared to Half/Squeezed SbS).

    You must remember that your passive screen ALREADY has 1/2 vertical resolution. You have worked through this, but have come to the consideration of converting to Field/Line interlaced. In general, this is NOT such a good idea: most 3D TVs do not include this as one of their accepted 3D input formats. The only ones GUARANTEED and REQUIRED/MANDATORY to be accepted are "FramePacking" (which is only an HDMI transmission format, not a storage format), HalfSbS and HalfTaB. That means ONLY FramePacking provides FullHD quality in both dimensions to both eyes (which is why MVC gets converted to FramePacking in 3DBD players). If you got this Field/Line interlace to work with your TV, you just happened to luck out, and only with that TV, not future one(s) you might get.
    Notice, though, that you will still get a Full quality/resolution Horizontal dimension by using the HalfTaB. It is both compatible with your quality needs, doesn't lose any other resolution (compared to your Passive's output) AND is HDMI 1.4-compatible MANDATORY. So, unlike the choice of Field/Line interlaced, it is guaranteed to work (possibly automatically) with your TV or any HDMI 1.4a-compatible 3DTV, for that matter.

    I also have to disagree with you regarding your statement about maximum necessary bitrate for 3D videos. 2D Blu-rays already have a max video stream bitrate of 40Mbps (with max muxed combined all-streams of 48Mbps). For many titles, this high of a max is necessary to realize the full quality potential of the title (because it is so visually complex). Just as the addition of color adds to the richness of the image - and needs corresponding increases in bitrate to accommodate this additional information, so too does 3D. Certainly not LOWER than regular 2D, which is what you are suggesting. 3DBDs limits have been upped to include single stream/single view max of 48Mbps, with a combined all-stream+all-views mux of 64Mbps. And you would need every "bit" of that available increase in headroom. 3D greatly adds to our perception even of 2D resolution, and because of the comparative capability of the interocular differences, your eyes/brain notices quality disturbance even more than in 2D.
    Ok, so you are talking re-encodes, but then all the talk about "full rez quality" might as well be thrown out the window, if you are 1) re-encoding (using a non-3D-optimized codec) and 2) encoding to a bitrate almost half of what was originally on the BD.

    Last edited by Cornucopia; 9th May 2014 at 01:08.
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