4 ms·

I would think you could hook into X11 to do this quite nicely.

algesten 10y ago
Problem is that grabbing the last frame buffer would mean you're doing it post decompression. To distribute something you grabbed like that you'd need to recompress it and then have a generation degradation of lossy compression.
- braveo 10y ago
  That's not how that works. It's one thing if you're converting from one compressed format to another, or recompressing an already compressed file. It's another to simply grab the pixels off of screen and compress those. You won't get as good of a shot because of the original decompression, but your description of why is inaccurate.
  - jshmrsn 10y ago
    algesten's comment seems entirely accurate to me. He's not claiming that the captured frame buffer will be of lower quality, but that in order to distribute it afterwords, you would need to recompress the captured frames. That recompression is where the quality reduction would occur. Everything I just said is rephrasing what is already in algesten's comment.
    - braveo 10y ago
      Because it has nothing to do with the original compression. Think of it like this. If you compress and distribute someone's wavy hand-cam pirating of a movie, the poor experience isn't due to the compression, but the way the move was recorded in the first place. likewise, recording a stream and then compressing it later, the quality isn't because of the original compression, it's because of the quality of the original stream. Now that poor quality may partially be the result of the initial compression, but recompressing it isn't why the quality isn't great.
      - azernik 10y ago
        Recompression matters because most video compression is lossy. Every compress/decompress cycle introduces noise and artifacts.
        braveo 10y ago
        right, which means by definition any compression is going to lose quality, even if done directly off the original, lossless versions. that's the point, it's the quality of the input that matters, not the fact that it's been compressed previously.
        rbutcher 10y ago
        Netflix sends you a video that has been lossy compressed once. If you lossy compress that lossy compressed video, then you will have a video of worse quality than the video that was only lossy compressed once. Original source video > Netflix video stream (1 level of lossy encoding) > Recompressed video stream (2 levels of lossy encoding)
        braveo 10y ago
        I think you'll find if you record and compress a netflix 4k video, the resulting quality will be just fine, especially if you're recording it and compressing it later (rather than doing it realtime). That's because, while it may have been compressed going over the wire, it's 4k and the quality is pretty stinkin' good. what you don't do is try to simply recompress the signal that netflix is sending you, you uncompress and then compress. At which point you're not "recompressing", what you're doing is compressing a stream that may not be as high quality as the original, uncompressed form, but it's a truckload better than sneaking into the theater and recording that way.
        rbutcher 10y ago
        Nobody has said that the quality would be bad, just that some amount of generation loss [1] will occur when you use a lossily compressed [2] video (the netflix stream) as input for the creation of another lossily compressed video (the "recompressed" video file). The "recompressed" video would be slightly worse than the streamed video, which would be slightly worse than the original video. An approximation of an approximation of a video is going to be worse than an approximation of a video. 1: https://en.wikipedia.org/wiki/Generation_loss https://en.wikipedia.org/wiki/Generation_loss 2: https://en.wikipedia.org/wiki/Lossy_compression https://en.wikipedia.org/wiki/Lossy_compression

Problem is that grabbing the last frame buffer would mean you're doing it post decompression. To distribute something you grabbed like that you'd need to recompress it and then have a generation degradation of lossy compression.

braveo 10y ago
That's not how that works. It's one thing if you're converting from one compressed format to another, or recompressing an already compressed file. It's another to simply grab the pixels off of screen and compress those. You won't get as good of a shot because of the original decompression, but your description of why is inaccurate.
- jshmrsn 10y ago
  algesten's comment seems entirely accurate to me. He's not claiming that the captured frame buffer will be of lower quality, but that in order to distribute it afterwords, you would need to recompress the captured frames. That recompression is where the quality reduction would occur. Everything I just said is rephrasing what is already in algesten's comment.
  - braveo 10y ago
    Because it has nothing to do with the original compression. Think of it like this. If you compress and distribute someone's wavy hand-cam pirating of a movie, the poor experience isn't due to the compression, but the way the move was recorded in the first place. likewise, recording a stream and then compressing it later, the quality isn't because of the original compression, it's because of the quality of the original stream. Now that poor quality may partially be the result of the initial compression, but recompressing it isn't why the quality isn't great.
    - azernik 10y ago
      Recompression matters because most video compression is lossy. Every compress/decompress cycle introduces noise and artifacts.
      - braveo 10y ago
        right, which means by definition any compression is going to lose quality, even if done directly off the original, lossless versions. that's the point, it's the quality of the input that matters, not the fact that it's been compressed previously.
        rbutcher 10y ago
        Netflix sends you a video that has been lossy compressed once. If you lossy compress that lossy compressed video, then you will have a video of worse quality than the video that was only lossy compressed once. Original source video > Netflix video stream (1 level of lossy encoding) > Recompressed video stream (2 levels of lossy encoding)
        braveo 10y ago
        I think you'll find if you record and compress a netflix 4k video, the resulting quality will be just fine, especially if you're recording it and compressing it later (rather than doing it realtime). That's because, while it may have been compressed going over the wire, it's 4k and the quality is pretty stinkin' good. what you don't do is try to simply recompress the signal that netflix is sending you, you uncompress and then compress. At which point you're not "recompressing", what you're doing is compressing a stream that may not be as high quality as the original, uncompressed form, but it's a truckload better than sneaking into the theater and recording that way.
        rbutcher 10y ago
        Nobody has said that the quality would be bad, just that some amount of generation loss [1] will occur when you use a lossily compressed [2] video (the netflix stream) as input for the creation of another lossily compressed video (the "recompressed" video file). The "recompressed" video would be slightly worse than the streamed video, which would be slightly worse than the original video. An approximation of an approximation of a video is going to be worse than an approximation of a video. 1: https://en.wikipedia.org/wiki/Generation_loss https://en.wikipedia.org/wiki/Generation_loss 2: https://en.wikipedia.org/wiki/Lossy_compression https://en.wikipedia.org/wiki/Lossy_compression