4 ms·

Even with DRM, if you can see it, it's decoded somewhere along the line. There will always be a way to get the raw video out of it if you're committed enough.

perching_aix 1y ago
That's actually an important distinction. You can recapture the DRM protected (and then decoded) video pretty much always indeed, but then you degrade the quality by having to encode it again. Well, not important to some, but for enthusiasts and people looking to actually archive things, it is very important. Case in point, hilariously, the last time I used YouTube's video download feature bundled with their Premium offering, I got a way worse quality output than with yt-dlp, which actually ripped the original stream without reencoding it. I think I saw an idempotent h264 encoder at some point, where you wouldn't suffer generational loss if you matched the encoder settings exactly from run to run. But then you might need the people mastering the content (in this case YouTube) to adopt that same encoder, which they're not going to be "interested" in.
- kuschku 1y ago
  Even with DRM video you can fetch it losslessly. At some point, some part of your system requires access to the raw, decrypted video stream. As long as that's the case, you can get bit-perfect netflix rips.
  - Marsymars 1y ago
    The problem is that if you have the raw data, you’ve lost the original compression information, so you can’t get it back to a sensible size without double compressing. e.g. Think about what you get when you save a jpeg as a bitmap.
    - kuschku 1y ago
      You can get the original compressed h264/h265/etc stream back out, that's the entire point. Even DRM media is using regular accelerated video decode.
      - perching_aix 1y ago
        The "entire point" of contemporary lossy-media DRM [0] is to prevent you from doing that. You can only do so if the DRM scheme is circumvented or unsound [1]. That is not what we're talking about - the working assumption here is that the DRM scheme is sound and effective. In which case your only possible but also guaranteed stage of recapture is at the analog hole, by which point the media encoding is already undone, incurring a generational loss. [0] I consider presently existing and historical DRM implementations deeply flawed and misguided; they severely overstep their boundaries implied by the name "DRM", in certain cases quite disgustingly - hence the many added adjectives for clarification [1] puzzlingly, any access control will actually get you in the same legal situation, regardless of whether the access control mechanism is effective or sound, so this is actually a design decision; but it's pretty universally taken afaik.
        kuschku 1y ago
        > That is not what we're talking about - the working assumption here is that the DRM scheme is sound and effective. Lol. That is not possible. If I'm able to watch something, my device must be able to decrypt the DRM. If my device can decrypt the DRM, I can take my device apart and figure out how it does this, and do it myself. The most DRM encumbered format is DCP, used my cinemas. Each projector has a unique key burnt into it, the decryption, decoding and watermarking happen on the same piece of silicon, and the entire device is built like an HSM, opening it wipes the keys. There are bit-perfect DCP rips on the high seas, with the original compressed data. HDCP is meant to prevent me from copying HDMI signals. Every conference center and lecture hall has cheap Chinese devices that remove it. Regarding the analog hole, with a properly calibrated professional video camera recording in RAW, with both camera and monitor genlocked and color calibrated, and the proper postprocessing, you can capure the original pixel values exactly. I've done that part more often than I'd like... And worst case, you can then brute force which parameters the original encode used to re-encode your data without generation loss.
dylan604 1y ago
circumventing the DRM is what will land you in legal hot water. storing the DRM encrypted media isn't the same offense

perching_aix 1y ago

That's actually an important distinction. You can recapture the DRM protected (and then decoded) video pretty much always indeed, but then you degrade the quality by having to encode it again. Well, not important to some, but for enthusiasts and people looking to actually archive things, it is very important. Case in point, hilariously, the last time I used YouTube's video download feature bundled with their Premium offering, I got a way worse quality output than with yt-dlp, which actually ripped the original stream without reencoding it. I think I saw an idempotent h264 encoder at some point, where you wouldn't suffer generational loss if you matched the encoder settings exactly from run to run. But then you might need the people mastering the content (in this case YouTube) to adopt that same encoder, which they're not going to be "interested" in.

kuschku 1y ago
Even with DRM video you can fetch it losslessly. At some point, some part of your system requires access to the raw, decrypted video stream. As long as that's the case, you can get bit-perfect netflix rips.
- Marsymars 1y ago
  The problem is that if you have the raw data, you’ve lost the original compression information, so you can’t get it back to a sensible size without double compressing. e.g. Think about what you get when you save a jpeg as a bitmap.
  - kuschku 1y ago
    You can get the original compressed h264/h265/etc stream back out, that's the entire point. Even DRM media is using regular accelerated video decode.
    - perching_aix 1y ago
      The "entire point" of contemporary lossy-media DRM [0] is to prevent you from doing that. You can only do so if the DRM scheme is circumvented or unsound [1]. That is not what we're talking about - the working assumption here is that the DRM scheme is sound and effective. In which case your only possible but also guaranteed stage of recapture is at the analog hole, by which point the media encoding is already undone, incurring a generational loss. [0] I consider presently existing and historical DRM implementations deeply flawed and misguided; they severely overstep their boundaries implied by the name "DRM", in certain cases quite disgustingly - hence the many added adjectives for clarification [1] puzzlingly, any access control will actually get you in the same legal situation, regardless of whether the access control mechanism is effective or sound, so this is actually a design decision; but it's pretty universally taken afaik.
      - kuschku 1y ago
        > That is not what we're talking about - the working assumption here is that the DRM scheme is sound and effective. Lol. That is not possible. If I'm able to watch something, my device must be able to decrypt the DRM. If my device can decrypt the DRM, I can take my device apart and figure out how it does this, and do it myself. The most DRM encumbered format is DCP, used my cinemas. Each projector has a unique key burnt into it, the decryption, decoding and watermarking happen on the same piece of silicon, and the entire device is built like an HSM, opening it wipes the keys. There are bit-perfect DCP rips on the high seas, with the original compressed data. HDCP is meant to prevent me from copying HDMI signals. Every conference center and lecture hall has cheap Chinese devices that remove it. Regarding the analog hole, with a properly calibrated professional video camera recording in RAW, with both camera and monitor genlocked and color calibrated, and the proper postprocessing, you can capure the original pixel values exactly. I've done that part more often than I'd like... And worst case, you can then brute force which parameters the original encode used to re-encode your data without generation loss.

dylan604 1y ago

circumventing the DRM is what will land you in legal hot water. storing the DRM encrypted media isn't the same offense