[HN Gopher] Why Can't We Screenshot Frames from DRM-Protected Vi...
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Why Can't We Screenshot Frames from DRM-Protected Video on Apple
Devices?
Author : ingve
Score : 45 points
Date : 2025-03-01 21:42 UTC (1 hours ago)
(HTM) web link (daringfireball.net)
(TXT) w3m dump (daringfireball.net)
| dTal wrote:
| Because you don't own the device, and the real device owner
| (Apple) is not working in your best interests. If you resent this
| kind of thing, put a penny in a jar every time software that
| you've paid for makes your life worse; when the jar is full, find
| a copy of Linux and install it. Spend the jar on whatever you
| want - it's free :)
| bigyabai wrote:
| Yup, case closed. If enough people cared about this then they
| wouldn't buy iPhones anymore. The market is speaking, and Apple
| is listening with rapt attention.
| walterbell wrote:
| Apple devices will happily play non-DRM content.
| what wrote:
| The reality is nobody cares. I don't think I've ever tried to
| take a screenshot of a movie and I'm sure most people haven't
| either.
| dghlsakjg wrote:
| You can't extrapolate your needs to everyone's needs. I've
| never needed to use a wheelchair for mobility, most people
| haven't. But that doesn't mean that we shouldn't consider the
| use case.
|
| What if you need to use a screen reader or magnifier for the
| text at the beginning of star wars. You would be pretty
| pissed if it was blocked by DRM. Hopefully pissed enough to
| sue under the ADA.
| kingo55 wrote:
| I would assume Linux wouldn't implement this but has this been
| verified somewhere?
|
| It's my understanding this limits the quality of content
| streamers permit to run on Linux:
|
| https://linuxcommunity.io/t/drm-the-final-barrier-to-linux-d...
| 827a wrote:
| I can confirm that screenshots are totally fine on Apple TV+
| on Firefox + Pop OS. I don't know what the quality is, but it
| looks at least 1080p and as great as I would ever want to my
| eyes.
| gruez wrote:
| Your suggestion for not being able to screenshot movies is to
| install linux, which doesn't support DRM (or does, but only at
| the lowest qualities)? Sounds like a pyrrhic victory to me.
| jsheard wrote:
| > I think Windows still offers easy screenshotting of frames from
| DRM video not because the streaming services somehow don't care
| about what Windows users do (which, when you think about it,
| would be a weird thing not to care about, given Windows's market
| share), but because Windows uses a less sophisticated imaging
| pipeline.
|
| The anti-screenshot mechanism also exists on Windows, but it's
| only enforced by stronger forms of DRM like Widevine L1.
| Typically streaming services mandate L1 or equivalent to watch
| HD/4K streams, so you can't easily screenshot those, only the
| lower resolution versions with weaker protection. The easy
| workarounds like disabling hardware acceleration really just
| disable strong DRM support so you get served a weakly protected
| low res stream instead.
|
| I guess Apple applies the same restrictions to all DRM protected
| content, even if the service only demands a weak form of DRM.
| ack_complete wrote:
| It's simple to enable on Windows, any surface with
| DXGI_SWAP_CHAIN_FLAG_DISPLAY_ONLY set will get excluded from
| screen capture APIs. No DRM is required.
|
| DRM isn't always the reason for video not being capturable,
| though. Efficiency optimizations can also get in the way, such
| as hardware video overlays. Back when overlays were first
| introduced, attempting to capture the screen would often omit
| the video because it would only capture the chroma key in the
| primary surface. Even today, the DWM has to undo multi-plane
| optimizations and specifically composite the screen when screen
| capture is requested.
| ChocolateGod wrote:
| Doesn't macOS also use this for power savings, rather than only
| DRM? This is something that Linux is also starting to pick up,
| and is probably one of the biggest reasons for Apple Silicon Macs
| having superior battery life.
|
| The GPU is the thing decoding the video stream and putting it
| directly on the display (via hardware planes). It doesn't need to
| send it back (aka copy) to the main CPU. Screenshots can't see
| what's there because the CPU has no knowledge of whats there.
|
| Rather than the GPU decoding the video, sending it back to the
| CPU which then will send the frame back to the GPU as part of
| composition, and wasting power.
| walterbell wrote:
| If the user requests a screenshot, the CPU can request a frame
| from the GPU.
| sxp wrote:
| > I think Windows still offers easy screenshotting of frames from
| DRM video not because the streaming services somehow don't care
| about what Windows users do
|
| This is incorrect. The DRM on Windows varies based on the
| browser. Trying playing Netflix in Edge vs Chrome and take
| screenshots. The video will be black on Edge but visible on
| Chrome. If you use Ctrl-Alt-Shift-D on Edge or Chrome to bring up
| the stats or view their test videos at
| https://www.netflix.com/watch/80164785, you can see that Edge
| plays 4k HDR but Chrome only plays 1080p SDR. Netflix allows
| 1080p with weak DRM but requires strong DRM for 4k.
|
| There are similar restrictions for mobile devices, VR headsets,
| etc. where the resolution is limited on certain devices and
| browsers because of their DRM configuration.
| perching_aix wrote:
| This even extends to screensharing on Teams. If I recall
| correctly, DRM protected content is completely black even when
| using Chrome.
| jandrese wrote:
| Yep, it's super annoying to pull up a movie on your machine
| and want to cast it over to the TV to watch and only getting
| a black screen because you didn't do the DRM dance correctly.
| giancarlostoro wrote:
| Pssst disable hardware acceleration.
| jsheard wrote:
| That works in a pinch, but the catch is that most streaming
| services will restrict you to watching at lower resolutions
| if you disable HW acceleration. The stronger DRM schemes
| they demand for high res playback require HW acceleration
| since they involve offloading decryption to the GPU.
| int_19h wrote:
| Coincidentally, this kind of thing is why you'll get 4K
| streaming on some browser/platform combinations but not the
| others. For example, Netflix will only give you 4K on Windows
| if you're using Edge or their own app.
| ViktorRay wrote:
| Yeah not many people know about this.
|
| https://help.netflix.com/en/node/30081
|
| This Netflix support page shows that 4K streaming is only
| available in the Edge web browser on Windows devices and in the
| Safari web browser on Mac devices.
|
| If you use Chrome or Firefox you get locked in to a lower
| resolution when using Netflix even if you are paying for 4K
| streaming.
| freehorse wrote:
| Can you trick it with a different user agent? Most of the
| times websites put arbitrary restrictions like this, it works
| by changing user agent for me.
| walterbell wrote:
| _> imposes a massive (and for most people, confusing and
| frustrating) hindrance on honest people simply trying to easily
| capture high-quality (as opposed to, say, using their damn phone
| to take a photograph of their reflective laptop display)
| screenshots of the shows and movies they're watching._
|
| Legally, public screenshots accompanied by text/audio/video
| commentary are fair use. When shared on social media, reviews, or
| fan sites with influencer commentary, they are unpaid marketing
| for video creators.
|
| Censorship of free advertising is against the economic interest
| of rightsholders. Is this checkbox compliance theatre, e.g. does
| everyone in the distribution chain mindlessly click a DRM button?
| Can Apple differentiate between DRM screen recording and DRM
| screenshots? Can Apple differentiate between 30-second
| promotional clips and longer recordings, or rate limit N captures
| per M wallclock time? Can rightsholders add metadata to enable
| screenshots on a per-title basis?
| bilalq wrote:
| This same issue prevents AirPlay from showing DRM video content
| on TVs. It's incredibly frustrating since Samsung TVs don't
| support Chromecasting.
| hapticmonkey wrote:
| The irony here is that despite all these DRM efforts, piracy
| groups upload 4K HDR (or Dolby Vision) atmos mkv files within
| hours anyway.
|
| Meanwhile watching these shows the legal way on unsupported DRM
| chain gives you 720p SDR with worse audio.
| t0mas88 wrote:
| This irony already existed in the good old DVD age. If you
| bought one legally you had to sit through several unskippable
| videos, usually also one about piracy, before the movie starts.
| If you had pirated that same movie would play immediately, so
| the user experience was better.
| crazygringo wrote:
| > _No one is going to create bootleg copies of DRM-protected
| video one screenshotted still frame at a time -- and even if they
| tried, they'd be capturing only the images, not the sound._
|
| I'm not defending Apple here, but -- yes they definitely would?
| And then they'd get sound on a second pass at regular speed.
|
| If pirates couldn't access the underlying Netflix etc. bitstream
| like they've figured out, they'd absolutely be reading the
| desktop video buffer, which is all a screenshot is.
| p0w3n3d wrote:
| That's not an argument. There is no law that prevents me from
| taking screenshots therefore I should be able to do it
| crazygringo wrote:
| Did you see where I started with "I'm not defending Apple
| here"?
|
| I'm just pointing out that one of Gruber's points doesn't
| really hold water.
| kuschku wrote:
| DRM isn't about release groups, and it never was. Actual
| pirates have a million different methods to capture video.
|
| DRM is a panic reaction to VHS, designed to making copying so
| inconvenient that casual users won't bother anymore.
| busymom0 wrote:
| A friend of mine who was taking a few Udemy courses last year ran
| into this issue when he needed to take screenshots for important
| things he was learning in the course. Ended up working around it
| by disabling GPU acceleration in chrome.
| freehorse wrote:
| It is annoying but not that tragic. Browser built-in
| screenshotting works fine (I use firefox) as does OBS. Only the
| builtin macos screenshotting tool gives black frames, which again
| is annoying and should not be the case, but there are
| alternatives that are ok at least.
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