DVD quality

Discussion in 'Digital Video' started by Supernerd, Jun 20, 2012.

  1. Supernerd macrumors member

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    #1
    I have a 1920x1200 pixel iMac, and I watch a heck of a lot of movies on it, often by DVD. It was this iMac that showed me how different DVD quality is from 1080p. However, I just watched Rise of the Planet of the Apes on DVD, and the quality of the DVD was extremely good, at least 720p or better, or at least seemed to be. I know it wasn't 1080p, but from a distance of about three feet, it was beautiful. How high can DVD quality go? Can you even put 1080p on a DVD and does anyone do this?
     
  2. simsaladimbamba

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    #2
    Video DVDs are limited to 720 x 576 pixel at maximum, 720p is 1280 x 720 pixel.
    Maybe the software you used to play the video DVD is that good at upscaling.
     
  3. floh macrumors 6502

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    #3
    This also just shows that to get an image that looks great, you can't rely on 1080p to do the task. A movie looking great is about lighting, lenses and camera work.

    I am always surprised at how much better commercial DVDs look than when I try to do something with a camcorder at the exact same resolution. :)

    That being said: You can pack BluRay folder structures on a DVD (if it's a very short movie), but it won't play back on a normal DVD player, just on a BluRay player.

    The DVD standard does not allow for anything but the aforementioned resolution (I think it differs slightly for NTSC norm in the US, this is European PAL...), everything better than that will have to be a different format (although not necessarily a different medium as I stated). The DVD Player in MacOS does the upscaling, and it does a very decent job at that.
     
  4. Supernerd thread starter macrumors member

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    #4
    Well, I have noticed that it is different than any other DVD I have watched, and 720p always seems fuzzy to me. I compared it to two DVD's, the same DVD's ripped via Handbrake, a 720p movie from iTunes, and Apes looked best to me. Maybe it's just how they shot it, or something about the compression. The 720p movie didn't have a single day scene either, and day scenes always look sharper. Maybe it's just me. Anyway, at this point, I don't think I am going to buy a DVD ever again, preferring iTunes movies, of which more and more are getting 1080p added, and boy, is iTunes 1080p sexy.

    Also, I am using plain old DVD player app to run them.
     
  5. arjen92 macrumors 65816

    arjen92

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    #5
    DVD player also upscales.

    Movies on a DVD have a size that's about 7GB. I'm not sure about itunes, but I can't imagine you're downlading 7GB in one hour for just one movie. (I can imagine it, but not from a service you're paying for like iTunes). So I assume the video is more compressed. Perhaps this compression loses more information. So even though you have more pixels, other aspects of video might be worse. (bit rate, color information etc).
     
  6. Supernerd thread starter macrumors member

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    #6
    Well, when I rip movies with Handbrake, I get a file that is usually around 1.3 GB, but I usually don't notice a difference between the rip quality and the DVD. I did once, on the DVD of X-Men First Class, the DVD had slightly better quality than the rip. Interestingly, that movie is from the same year as Rise of the Planet of the Apes, the DVD that appeared to have really good quality. That's what i thought at first; that Planet of the Apes looked better because it was a newer DVD. I really want to rip Apes to see what that's like, but it's not mine, and I rip legally. however, I do think this effect could have something to do with the compression of something besides the resolution, or something, like color... I don't know, but I do know that a red caution tape in the movie appeared really pixelated as opposed to the rest of the movie. I would love to know what causes this DVD seem better quality, because I would like to be an independent filmmaker and I would love to work this into DVD's, because I have ho idea how to burn Blu-rays. And I don't have a Blu-ray player anyway.
     
  7. TyroneShoes2 macrumors regular

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    #7
    If you are ripping a 7 GB movie to 1.3, that means you are discarding about 82% of the information that was remaining when it was compressed to 7 GB originally, during that transcode. So yes, that will be a compression level that will be noticeable from the DVD, especially on motion.

    Broadcast TV in HD can discard 99% of the original information (1.485 gbps to 14.85 mbps or less) and still look pretty darned good, but when you compress a file secondarily that is already compressed greatly, the concatenation means rounding errors accumulate significantly. It's similar to trying to create a 128 kbps MP3 from a CD quality file. That works pretty good, but if you try to do that starting with a 256 kbps file, the resulting 128k file will not be nearly as good (which is why Apple is trying to get record companies to supply original 192 kHz 24-bit masters for them to make their 256k library copies from).

    One of the things that most folks don't realize is that even if your compression level is severe, if you have enough bits, it will not create artifacts at all.

    Also, where compression breaks down is usually only on motion. Still shots even in compressed video have few if any artifacts.

    Quality also depends on how well the deinterlacing from 1080i or 480i is done to 720p. 1080i, 1080p, and 720p all have essentially the same perceived resolution, all else held equal, surprisingly enough, but if the source is 1080i and is converted to 720p and the deinterlace is done badly, that image will suffer.

    1080p will have slightly better dynamic perceived resolution (when objects move or the camera pans or trucks or dollys) than 1080i, but on still images it will look exactly the same as 1080i. Also, most 1080p is 1080p24, meaning the motion artifacts on 1080p are actually greater than on 1080i (motion will be sharper, but it will be jumpier from the slower flicker frequency).

    And SD these days does look pretty darned good. One of the reasons is that most of the signal chain is now HD, and this preserves the quality all the way to the final downconvert, where in the past there was an increase in fuzziness and a loss of color and an increase in noise for every step in the chain, and there are a lot of steps so the cumulative effect was crappy SD.

    The only thing that HD has (other than usually a wider aspect ratio) over SD is increased sharpness. Every other aspect is exactly the same as SD. The color gamut and color space is the same, the audio is the same, the contrast ratio is the same (again, all else held equal).

    Also, the distance you view from makes a huge difference; we can't even see HD resolution from the distances that most folks view HD from in their homes; it's better than SD, but not as good as it would be if they sat closer. You have to sit less than 7.8 feet away from a 1920x1080 image on a 60" screen to fully resolve HD, and most folks sit 10-15 feet away from a 50-55" image. If you are viewing from a distance that keeps you from resolving the sharpness of HD, it really might as well be SD, because sitting that far away removes the single thing that distinguishes HD from SD.
     
  8. Supernerd thread starter macrumors member

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    #8
    TyroneShoes2, you equally know what you are talking about. I was wondering why DVD video is about 7gb. If DVD is SD, then, at least by iTunes compression, it should be about 2gb. What else is there that makes it so much memory? ITunes compression can't be that legendary...

    Ok, maybe it can. If they can make really good-looking 1080p be almost the same size as 720p, that's impressive. But what is iTunes cutting to make it like that?
     
  9. blueroom macrumors 603

    blueroom

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    #9
    DVD video uses a pretty old codec MPEG2
    Very modern codecs MPEG4 layer 10 have some amazing qualities and can compress with very little perceivable loss in quality.
     
  10. NewbieCanada macrumors 68030

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    #10
    If the original poster is American, Canadian or from another country using NTSC, DVD is limited to 720x480.
     
  11. mBox macrumors 68020

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    #11
    Sim was correct though, he referred "limited to 720x586 at max...".
     
  12. Supernerd thread starter macrumors member

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    #12
    Ok, blueroom, so my original topic, Rise of the Planet of the Apes DVD seeming to have really good quality, could it have just been compressed onto the DVD with a higher level of MPEG? Would that make a difference in how it looks?
     
  13. floh macrumors 6502

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    #13
    Nope, sorry. :)

    If it's a DVD, it is restricted in resolution and also codec. It is even restricted in the bitrate it can have. If a DVD does not follow these standards, it can most likely not be played on a standard DVD player. The DVD standard is very precise and you can read it here for example.

    The codec is fixed, and so is the resolution. The only thing you can play with is the bitrate, which (as far as I remember) has to stay below 11 Mbps including audio. If you want to, you can check the bitrate of your DVD if you place it in your optical drive and open the "main" file with MPEG Streamclip. Then you press Cmd-I to open the stream information window and you can read the video bitrate there, it looks something like this:
    Bildschirmfoto 2012-06-25 um 21.36.54.png

    When it came out, I bought a package of "Rise Of The Planet Of The Apes" that contained the DVD, the BluRay and a digital 720p version from iTunes. So far, I have only watched the BluRay, but if you are really interested, I can check out the difference in looks.

    Have you compared this with other movies that are well known for their "great look" on the same player setup? I'm pretty sure there are homepages out there that are comparing the quality of mastering on published DVDs. Maybe they have some information...? You can certainly do a lot that is not related to the codec or the resolution that will make the final film look better. But neither codec nor resolution are open to experiments, and the bitrate is also very restricted.
     
  14. Supernerd thread starter macrumors member

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    #14
    Do you know any examples of this? I would love to look into that...
     
  15. floh macrumors 6502

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    #15
    Well, I know some German sites that review DVDs and a google search mostly delivered me those (they know where I live...). A first search got me dvdtalk.com, which describes (at the very bottom of the page) the image quality of "Rise of the Planet of the Apes" as very good but not outstandingly great.

    Just like this page, most DVD reviews usually contain a few remarks on image and audio quality of the reviewed DVD. At least that's what I'm used to. So I would suggest to search for a normal DVD review site (yeah, those get rarer...) that is to your personal liking.

    Making a direct quality comparison between DVDs is very difficult, since no two movies look the same, and some movies' look is just better suited for DVD than another. And, as I've said before, a lot of things go into how good a movie looks beside the final DVD render. In case of "Rise of the Planet of the Apes", it is probably very beneficial that the movie is not too contrasty and dark and overall has bright and light flooded images. DVDs are not very good at contrast and dark areas and something like Ridley Scotts "Alien" will most likely have more noticeable artefacts.

    Sorry I can't be of better help here.
     
  16. LethalWolfe macrumors G3

    LethalWolfe

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    #16
    While the pixel resolution, codec, and data cap all provide limitations there still is a surprising amount of room to work with. Not all encoding engines deliver the same quality (even when the codec is the same), edge enhancement and noise reduction need to be handled gracefully, and multi-pass and variable bitrate encoding allow compressionists to really fine tune how many bits each shot gets so that simple shots (like basic credits) aren't hogging too many bits and complex shots (like a car exploding) don't break apart from being bit-starved.


    Check out a site called The Digital Bits. Many times when they review movies they talk about image and sound quality and not just how good/bad the movie is. For example, check out this review of the Alien Quadrilogy from a few years ago.


    Lethal
     
  17. TyroneShoes2 macrumors regular

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    #17
    There is much of your answer, right there.

    For general video, you can use a MPEG-4 bit rate of half that of MPEG-2 and get equivalent quality. In practice the yield is more like a 30% reduction in bit rate. An equivalent bit rate for the same quality for 1080i30 as for 720p60 is that the 720p60 version can be about 7/8ths that of 1080i30. 1080p24 can run at 4/5ths the rate of 1080i30, which is even lower, and may be why it is becoming the de facto standard for streaming.

    DBS takes MPEG-2 from local TV stations broadcast at about 11-14 mbps, and crosscodes it to MPEG-4 at about 7.5 mbps for delivery, but they do it without a downconvert and with high-end transcoders, and with help from statmux, which yields a sat-delivered image quality that is virtually indistinguishable from the original broadcast.

    But I have recently been informed that iTunes uses 720p30, or at least that is what older AppleTV boxes are doing. This means a bit rate half that of normal 720p60, because every other frame is basically tossed away. This would then require a bit rate only 7/16ths what 1080i30 requires, for "equivalent" freedom from compression artifacts (traded in for increased motion artifacts and lower resolution).

    The delivered pixel rate of 1080i30 is about 4.5 times that of conventional SD, so an SD bit rate for equivalent quality can be about 22% that of HD. That's how cable TV can get 10 SD channels into a single QAM channel, but only 2 HD channels in a single QAM channel.

    And good SD is not really all that different from HD. The only thing HD is, is sharper; the color gamut, contrast ratio, and audio quality are exactly the same. We are so used to SD being associated with analog delivery, where every one of the numerous links in the delivery chain compromises sharpness, color fidelity and noise which cumulatively means a virtual mess by the time it gets to the TV, that it is really surprising how good SD can be, and not surprising at all that SD DVDs ruled the day for so long.
     
  18. Magrathea macrumors regular

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    #18
    All about resolution / data rate + camera.

    It all has to do with the cameras they are using and the resolutions and how much data they capture. The best HD cameras in the world only resolve 860 lines or so of resolution. All other cameras are less. DVD is what, 720 lines or so . So if you use a $50 / $100k camera that can actually get that much clean nice looking resolution and a big data rate into a DVD it'll look great.

    I have a hacked GH2, this ups the bit rate from 24Mbps to 150Mbps, it has amazing resolution. When I crunch it down to a DVD, wow it looks great. The noise actually looks like film grain - all from an $800 (minus lens) camera.

    That's my theory, but DVDs still have an inferior codec from the 80s or so.
     
  19. Supernerd thread starter macrumors member

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    #19
    My TV is probably from the 80's or so. I just bought an Apple TV, but figured out on the way home that I would need a 250$ converter to get it to work with my TV because it's so old. I probably won't even get a Blu-Ray player, I'll just watch movies on my iPad and iMac until I get a new TV.
     
  20. mBox macrumors 68020

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  21. LethalWolfe macrumors G3

    LethalWolfe

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    #21
    It's true that if you are using a 1920x1080 sensor you are never going to resolve 1080 lines which is why the trend is to go to oversized sensors so, if done properly, you can pull a clean 1920x1080 image from them. So the best, and even the not-so-best, HD cameras can resolve 1080 lines (not to mention the bigger than HD cameras like RED and Alexa). NTSC DVD is only 480 lines.
     
  22. Supernerd thread starter macrumors member

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    #22
    Possibly. If anyone knows anything about the rumored Apple TV, it's that it won't be 3D, Apple hates that kind of stuff, and I kinda want a 3D TV. I looooooooove 3D.:cool:
     

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