As televisions and TV service has gotten more and more sophisticated since the switch over to digital, the insides of your TV have gotten more and more complicated. What’s actually inside those TVs and how do they tick? Well, it’s both simple and complicated.
In the United States, almost all television is viewed by some pay-TV operator (think cable or satellite) and your TV acts as a display. There’s a ton of smarts and processing in the TV to smooth out the video, deblock compression artefacts, process the audio, etc. But the core part of the video experience is delivered by the cable box and delivered through the HDMI cable. Since the cable or satellite company own the entire pipe, they are normally built with custom made solutions by companies like NDS, OpenTV, and the like. A small percent watch broadcast TV in the United States (think bunny ears). In that case, specs made by the ATSC describe how the digital broadcast is supposed to work and the TV does all the heavy lifting.
In other markets, like in Europe, there is a lot of free-to-air broadcasts, and they’re specified by groups such as the Digital TV Group in the UK or DVB in Europe. Like ATSC in the US, these standards basically describe how broadcast digital TV is supposed to work, including things like the video codec, the audio codec, channel guides, any other data in the stream.
Most broadcast systems in the world currently use MPEG2 as the video codec, and can transmit in the high 10s of bandwidth per carrier, typically the US about 18 Mbps. Systems such as DVB-T2 are looking to move to H.264 as their video codec standard to more efficiently use the same amount of bandwidth.
But enough about codecs, how does it all work? It’s acutally pretty simple. Inside the TV (or cable box) there are a bunch of electronics and at the core of it is a system-on-chip or SoC. In the TV world, there are a few quite a few companies that make these SoC, such as Broadcom, MediaTek, STMicro, Trident, Intel, Zoran, MStar and probably more I can’t recall off the top of my head. These SoCs handle all the work required to make TV happen. They process the incoming stream, whether it’s a raw feed from a cable, satellite or broadcast TV feed, decrypt the streams if it’s protected, then decode the audio and video and sync it up, then sent it along, either to the display or on to the TV.
This picture is the inside of a flat planel TV. There are there major components shown here. On the far right is the logic board. On the logic board is the SoC, connectors to HDMI, cable and audio, memory chips, and a few other parts. In the middle is the power system, which powers the actual panel. On the far left is the speaker. The most impressive part of these systems is how slim hardware vendors have now managed to make everything while still retaining quality, especially around the audio from the speakers.
TVs (and set top boxes) are typically very very good at decoding and rendering video. They can typically decode Bluray quality in their sleep (to put it in context that’s roughly 39 Mbps of data), all the while doing all kinda of real time image and video processing to make it look even better. It’s really quite impressive how much data goes through a TV system in a second when rendering 1080p (1920w * 1080h * 24fps * 24bit color + 448kbps-ish of audio).
So that’s how your TV works! Easy, right?