50 ms·

I wonder if it has to be a real computer, display, and camera, or if doing it with a "headless display" that is nonetheless being fed to a "video recorder" woul

I wonder if it has to be a real computer, display, and camera, or if doing it with a "headless display" that is nonetheless being fed to a "video recorder" would work... Funny how it'd be like The Matrix...

crazygringo 1y ago
It depends on a lot of factors. But even if it works in a virtual machine, your CPU is going to be pegged at 100% the whole time to handle the re-encoding. Unless you use a hardware h.264 encoder, but then the quality is pretty terrible since it's explicitly optimized for speed over quality and isn't tunable the way software encoders are. It's always doable, it's just an option of last resort. You always just want to access the original compressed bitstream if possible.
- tracker1 1y ago
  I think the real key is to only compress enough initially so that you don't blow out your storage in terms of size and throughput... Once you have the stream captured at a higher quality, you can always recompress more optimally. A relatively low compression with hardware h.264 will still take up a lot less space and throughput than mpeg-2 or raw.
  - netsharc 1y ago
    The ultimate hack would be to intercept the data stream after the decryption, but before the decoding, so you get still-compressed H264 or whatever... I suppose it's possible that they use a codec where the decryption also means decompression...
npteljes 1y ago
I have written software to do this kind of recording on a laptop, running 4 of the stream itself (different episodes of the same show). It opened DRM enabled browsers side by side, ffmpeg captured the video from the respective parts of the screen, and each browser's audio was piped into a different dummy output, which ffmpeg also captured of course. The tech stack was linux, bash, PHP, php-webdriver, Selenium, Firefox, ffmpeg. So yes, this idea absolutely works! That is, until they crank up the DRM so that software screen capture doesn't work.
- pabs3 1y ago
  Just move the capturing a layer further away, there is always the analog hole.
  - npteljes 1y ago
    Yes but why waste $10-$20 on a cheap HDMI recorder, when I can create this beautiful software in two person-days of work?

crazygringo 1y ago

It depends on a lot of factors. But even if it works in a virtual machine, your CPU is going to be pegged at 100% the whole time to handle the re-encoding. Unless you use a hardware h.264 encoder, but then the quality is pretty terrible since it's explicitly optimized for speed over quality and isn't tunable the way software encoders are. It's always doable, it's just an option of last resort. You always just want to access the original compressed bitstream if possible.

tracker1 1y ago
I think the real key is to only compress enough initially so that you don't blow out your storage in terms of size and throughput... Once you have the stream captured at a higher quality, you can always recompress more optimally. A relatively low compression with hardware h.264 will still take up a lot less space and throughput than mpeg-2 or raw.
- netsharc 1y ago
  The ultimate hack would be to intercept the data stream after the decryption, but before the decoding, so you get still-compressed H264 or whatever... I suppose it's possible that they use a codec where the decryption also means decompression...

npteljes 1y ago

I have written software to do this kind of recording on a laptop, running 4 of the stream itself (different episodes of the same show). It opened DRM enabled browsers side by side, ffmpeg captured the video from the respective parts of the screen, and each browser's audio was piped into a different dummy output, which ffmpeg also captured of course. The tech stack was linux, bash, PHP, php-webdriver, Selenium, Firefox, ffmpeg. So yes, this idea absolutely works! That is, until they crank up the DRM so that software screen capture doesn't work.

pabs3 1y ago
Just move the capturing a layer further away, there is always the analog hole.
- npteljes 1y ago
  Yes but why waste $10-$20 on a cheap HDMI recorder, when I can create this beautiful software in two person-days of work?