Expanded 4K videos from YouTube are not clear on 4K TV

Discussion in 'Mac Basics and Help' started by hajime, May 16, 2018.

  1. hajime macrumors 601

    Joined:
    Jul 23, 2007
    #1
    Hello, I connected a MBP 2017 13" to a 49" TV. When viewing 4K videos on Youtube from a browser, the video images looked very nice and clear. However, when I expanded the videos to full size, the images did not look clear. Kind of fuzzy. How come? Shouldn't 4K TV display 4K video crystal clear even the videos are shown in full screen mode?
     
  2. chrismac2 macrumors regular

    chrismac2

    Joined:
    Jan 14, 2008
    Location:
    Seattle, WA
    #2
    Have you tried watching them in Chrome? I know Safari does not support the VP9 codec that Youtube uses for 4k videos. But I believe Chrome does. So when viewing in full screen on Safari, you'll only get 1920x1080 resolution (HD)

    Also, are you sure you Mac is being detecting your TV display resolution, and outputting the same?
     
  3. hajime thread starter macrumors 601

    Joined:
    Jul 23, 2007
    #3
    Thanks. Just tried Chrome but it is still the same. After some searching, it seems that there may be a possible reason.

    When I was at Apple Store, I told the guy that I wanted to connect a MBP 2017 to a 4K display. I told him that I want 4K@60Hz with Chroma 4:4:4. He mentioned other adapters had problems and strongly recommended me to use the USB-C Digital AV Multiport Adapter. He said that he is sure it would work. However, I just checked the specs of this adapter on Apple's website. It states "this adapter allows you to mirror your Mac display to your HDMI-enabled TV or display in up to 1080p at 60Hz or UHD (3840 by 2160) at 30Hz." So, this guy sold me an adapter that does not do 4K at 60Hz?

    Do you think this could be the reason behind my problems?
     
  4. chrismac2 macrumors regular

    chrismac2

    Joined:
    Jan 14, 2008
    Location:
    Seattle, WA
    #4
    I'm still curious to see what resolution your Mac says it's outputting. But yeah, that adapter won't do 4k at 60Hz. But I would think your tv would still accept 4k at 30Hz, and upscale it to 60Hz
     
  5. hajime, May 17, 2018
    Last edited: May 17, 2018

    hajime thread starter macrumors 601

    Joined:
    Jul 23, 2007
    #5
    Under Display, I can choose different resolutions. I chose 3840x2160. I pressed the Display button on the remote controller of my Sony 49X900E TV. It shows that 3840x2160p 4K, 16:9 on the screen. So I think the Mac is outputting 4K. I am using this cable:

    https://www.amazon.ca/gp/product/B002U38E9O/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

    I have also tried another HDMI cable (bought many years ago. not sure if it is 2.0 or 1.0) but there is no change in my situation.

    I have 3 questions:

    1. That adapter outputs 30Hz so it causes the lags in dragging the mouse pointer and windows. Does a 4K@30Hz adapter leads to some unclear video images when expanding the youtube playing window? It is like watching things with a glass that is not completely clean.

    2. Under Display, what color display profile should I choose? I just use HD 709-A by default. Not sure that that means.

    3. Sometimes big dark images (e.g. black or dark suit people are waring) shows up like blocks of dark images. Very ugly. Does not matter if the videos are in 1440p HD or 1080p HD.
    For example:

    (1st image, 0.44/2:48, 1440p HD)
    (2nd and 3rd image, 1080p HD)

    How come?
     

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  6. Unami, May 17, 2018
    Last edited: May 17, 2018

    Unami macrumors 6502a

    Joined:
    Jul 27, 2010
    Location:
    Austria
    #6
    afaik some adapters - like apple‘s - are limited to 30hz. you need a hdmi 2.0 compatible adapter, tv and cable. even then it‘s probably easier to do this via displayport (and adapter, if necessary).

    @ refresh rate - there should be no difference in sharpness between 60hz and 30hz, but if your tv interprets the refresh rate (in combination with the resolution) wrong, or one point (cable, tv) is not compatible this could result in a blurry picture.

    rec 709 is the color space for hd - if you want 4k hdr, you need to set something different (eg. bt2020). but most youtube videos are in 4:2:0, 8 bit chroma-sampling anyway, rec709 should work fine, i guess.

    those blocks are compression artifacts - youtube’s compression reduces the original file by a factor of - i don‘t know 100? - in comparison to an uncompressed 444 stream - so something‘s got to give. remember, one already heavily compressed blu-ray 4k movie has about 66-100gb, whereas a youtube video of the same length has about 6-10 gb. you could lower the black level of your tv, so you don‘t see those artifacts in the dark areas. almost all tvs are factory-set to a much to high brightness-level (also called „torch mode“, to stand out in the shop) anyway, so you‘ll see a different picture than the producer of the movie color-graded for.
    --- Post Merged, May 17, 2018 ---
    btw., turn off all the „noise reduction, motion smoothing, contrast optimization, probably even „upscaling“,... crap on your tv. that puts you at the mercy of the software in the tv - e.g. samsung is famous for it‘s crappy sw - and shows you the pictures not as they were intended to show. this could also be the cause of your problems.
     
  7. hajime, May 17, 2018
    Last edited: May 17, 2018

    hajime thread starter macrumors 601

    Joined:
    Jul 23, 2007
    #7

    Thank you. So I should not expect crystal clear 4K viewing of videos on youtube?
    What suggestion do you have at this stage? Getting sharp text and smooth movements is the first priority followed by nice looking 4K videos.
     
  8. hajime thread starter macrumors 601

    Joined:
    Jul 23, 2007
    #8
    Hello, I came across this:

    https://www.macrumors.com/guide/4k-5k-displays-buyers-guide-mac/

    I don't know much about USB-C and Thunderbolt.

    Under HDMI, it states that "The latest Macs have HDMI 1.4, which can only drive one Ultra HD display at 30 Hz or one 4K display at 24 Hz with no mirroring. Apple has not released any Macs with HDMI 2.0, which can drive a 4K display at 60Hz."

    Then: "Bottom Line: Thunderbolt is better than HDMI because it can drive 4K and 5K displays at up to 60Hz, whereas HDMI is limited to 30Hz or 24Hz on current Macs."

    Does that mean it is better to use Thunderbolt? Given that my Sony 4K TV has no thunderbolt port nor displayport port, I can only use HDMI 2.0 port.

    Does that mean I need a Thunderbolt to HDMI 2.0 adapter rather than an USB-C to HDMI 2.0 adapter if I want to have 4K @ 60Hz on the external 4K TV?
     
  9. hajime thread starter macrumors 601

    Joined:
    Jul 23, 2007
    #9
    Just tried the Anker USB-C to HDMI 2.0 adapter. I still have poor image quality issues with the Mission Impossible videos. Could it be that although they said the videos are 4K, they are not in reality? Could those with a big 4K screen 40"+ try the videos and let us know if you also have poor image quality?
     

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