Building a PVR for a HDMI output
Back in the day, we had more freedom to do what we wanted with TV signals coming into the home. We could simply plug the antenna into the VCR, and run another cable from the VCR through to the back of the TV and record whatever we wanted, whenever we wanted. AND, we could fast forward through all the annoying adverts.
Nowadays, it is apparently “illegal” to record from the TV; at least, that is my impression. They definitely make it very difficult to do so. In the UK, we can purchase Freeview and Freesat set top boxes with an actual hard drive to use as a PVR; Sky Q does the same and so does Virgin Media. The problem is that those recordings are encrypted and can only be stored and played back on that box. That means that they cannot be exported or viewed on any other machine.
The reasons are valid enough; licensing and copyright rules and all that. Gone are the days when I could pass my video cassette recording of the Saturday night music video show to my neighbour because he missed it, and I could borrow his recording of The Fresh Prince of Bel-Air episode that I couldn’t watch.
I miss those days. I’m going to bring those days back into this digital age.
I have a Sky Stream subscription which comes along with its own cute little box called a “puck”. It’s horrible hardware (slow AF) but it does what it is supposed to do. Being a streaming-only box and service (like a Fire TV stick) it is not capable of recording. Instead, users have to add a show to a “playlist” and the box is smart enough to push the entire series into that playlist so that it can be binged-on later. The catch 22 here is that I have no idea how long those playlists last. So, if I save something in 2026, will it still be there in 2029? Probably not.
How can I record?
I intended to put everything into this one post, but the more words I type, the more I realise that there is a lot to cram in. I’m not in a mood to be concise and succinct about this! A lot of thought and trial and error went into the solution so I think I will flesh it out a bit.
The set top box has one HDMI output which is intended to plug into the back of the TV. HDMI itself is encrypted and it looks for a “monitor” on the other side when it performs its handshake. Furthermore, no laptop or PC I know of has an HDMI input; those are all HDMI outputs as well.
My first challenge was to see if I could somehow split the output from the set top box in two. One will go into the back of the TV and the other can go into the back of something else… let’s call it “Monitor 2”.
The second challenge was then to figure out how to somehow capture the signal intended for Monitor 2. Will it be a decrypted signal feeding into there? It needs to be for this to work.
- Split the set top box output
- Somehow capture the decrypted signal