The resolutions side by side
| Label | Pixels | Lines | Where it’s defined or used |
|---|---|---|---|
| SD (UK) | 720 × 576 | 576 | Standard definition, from the PAL era |
| HD (720p) | 1280 × 720 | 720 | A common HD streaming size |
| Full HD (1080i or 1080p) | 1920 × 1080 | 1080 | ITU-R BT.709 (HDTV) |
| 4K UHD | 3840 × 2160 | 2160 | ITU-R BT.2020 UHDTV |
| 8K UHD | 7680 × 4320 | 4320 | ITU-R BT.2020 UHDTV |
Each step up roughly doubles or quadruples the pixel count: Full HD has 2.25 times as many pixels as 720p, and 4K has four times as many as Full HD.
“i” and “p”: interlaced and progressive
- Progressive (p) sends every line of every frame: 1080p at 50 frames per second is 50 complete pictures a second.
- Interlaced (i) sends alternate lines in two halves, called fields: 1080i at 50 fields per second is 25 complete pictures, woven together.
A lot of broadcast HD in Europe is 1080i, and IPTV channels taken from broadcast keep it. Your device or TV has to deinterlace it, and how well it does that shows in fast motion and scrolling text. Apple’s HLS authoring specification requires interlaced sources to be deinterlaced for its devices. See IPTV lagging for deinterlacing settings.
Resolution needs bitrate
A resolution is only a frame size. Whether the picture looks sharp depends on how much data per second, the bitrate, the stream uses to fill it. Apple’s example bitrates for its devices show the scale:
| Resolution | H.264 | H.265 (HEVC) |
|---|---|---|
| 720p | 3 to 4.5 Mbps | 2.4 to 3.4 Mbps |
| 1080p | 6 to 7.8 Mbps | 4.5 to 5.8 Mbps |
| 4K | – | 11.6 to 16.8 Mbps |
A 1080p channel squeezed far below those figures can look worse than a generous 720p one. That’s why two channels labelled “HD” can look so different. See poor picture quality.
When higher resolution shows
- Screen size and distance. On a small screen, or from across a large room, the difference between 1080p and 4K is hard to see. On a large TV viewed from the sofa, it shows on fine detail such as grass and crowd shots.
- The source. A 4K TV can’t add detail to an HD channel; it upscales it. See IPTV picture quality.
- Your connection. 4K needs a steady connection with headroom above the stream’s bitrate. See internet speed for IPTV.
4K and 8K on IPTV
Most live IPTV channels are HD or Full HD. 4K channels exist, usually for sport and films, and need a 4K device, an H.265 decoder and a steady connection. 8K streams are rare, and few devices can play them. Our 8K and 4K IPTV page explains what our service offers.