Using IP for TV in your room
The main entertainment point is the lounge at the moment, with the TV feed coming in from cable. Next week, if all goes to plan, Sky will be up and running too. So what if I want to watch it in my room rather than the lounge?
I’m putting my TV in the lounge, and don’t want to buy another one. Also, don’t want to put RF leads around the apartment. So why not use the PC or laptop, and the existing IP connection? We have wireless everywhere, and hope to get bridges so we get wired for various pieces of equipment that can’t go on wireless.
Also means TV in the kitchen while cooking and stuff.
Method…
So I figured I can get an input to an encoder one of two ways, using SCART from each and two input devices, or one RF feed with both devices on seperate channels, and one input device. The latter is the cheaper, only having to buy one TV/capture USB thing. The picture input quality is important, but RF from a device should be great if it’s set up OK. Originally thinking that mono sound encoding through RF wouldn’t be a problem, it is required if I want to switch between input devices without hardware reconfiguration.
Then I figured, cable is going away soon, so let’s keep it as one input device. Makes it simple, and I can use scart to sVideo with stereo sound. Yey all round.
Hardware…
So the plan is, use a linux box (almost certainly a spare dual-core laptop with 256MB RAM, plenty for encoding a stream I should think), using VLC encoder and a USB input dongle thing. Using a laptop keeps the power consumption right down, doesn’t use space and fits under the TV stand. Also I can install Apache on it and serve pictures of cake at the same time.
CODEC…
What CODEC should we use? I think H.264, it’s good quality and with VLC, easy to configure. The latency that we will get isn’t bad but it’s hardly instant, probably around 5 to 8 seconds. But I don’t really know, maybe if the bitrate is ramped up a bit… experimentation is key, we will see. Most likely try 2-3mbps video and ~228k joint stereo audio, AC3? or MP3… Nah AC3. Why not, we’re using H.264 as video, so if the player can decode that, it can do AC3 I should think.
Resolution and processing…
720x576, or resize to 640x480? Or… thinking about it, most programs are widescreen at the moment aren’t they, so I guess input at 720x576 with 1.334 pixel aspect, I think that’s what the sky box chucks out. Well it doesn’t actually does it, because the output is analogue, but my mind tells me that is what the encode will look best at.
Considering the viewing device will be a progressive display, we should deinterlace the video. VLC has all sorts of fun algorithms for that, when doing some upscaling tests a while back I found Linear to be nice, but we will see with experiments I guess. I just don’t like interlace lines, very apparent when upscaling on progressive displays that are a higher resolution than the input. An inpact on CPU but nice to have.
Changing channel?
Be nice to be able to change channel. Won’t be implementing this from the get go but be cool to use the RS232 socket on the Sky box and some scripts to push channel change info to the box. I don’t know the protocol but I’m pretty sure it does work, it’s how the old Gnome radio thing changed channels.
So, that’ll be nice to try eh….
3 years ago