Resolution: how many pixels the picture has
Resolution is how many pixels make up the picture — the bigger the number, the finer the image:
| Label | Resolution | Notes |
|---|---|---|
| 480p (SD) | 854×480 | Standard quality, a safe option on a poor connection. |
| 720p (HD) | 1280×720 | High definition, usually plenty on a phone. |
| 1080p (FHD) | 1920×1080 | Full HD, currently the mainstream. |
| 4K (UHD) | 3840×2160 | Ultra HD; the difference is only obvious on a large screen. |
But higher resolution does not always mean sharper — the key is also the "bitrate" in the next section.
Bitrate is the real key to sharpness
Bitrate is how much data per second is used to render the video. This is the real reason "the same 1080p looks sharp in one version and blurry in another":
- High bitrate: detail and motion are preserved well; the file is also large.
- Low bitrate: the picture shows "colour blocks" and "mosaic-like noise", especially in motion scenes; the file is small and easy to stream.
What HDR, frame rate and codec are
- HDR: High Dynamic Range. Makes bright areas brighter, dark areas show more detail, and colours richer. You only see the effect if the video itself is HDR and your screen supports HDR.
- Frame rate (fps): how many pictures per second. Common values are 30fps and 60fps; higher means smoother motion.
- Codec: the video's compression format, commonly H.264 and H.265 (HEVC). H.265 gives a smaller file at the same quality, but older devices may not support it.
How to choose: quality vs smoothness vs data
Higher quality is not always better — it is a three-way balance:
- Phone viewing: 720p–1080p is usually enough; the screen is small and the 4K difference is hard to see.
- Large screen / TV: only here is 4K really worth choosing.
- Limited network or data: lower the resolution, or pick a lower-bitrate version, to trade for smoothness.
For troubleshooting actual playback stutter, see "JAV Buffering on Mobile".
FAQ
Why do some "1080p" videos look blurry?
Because resolution is only one factor. If the bitrate is compressed too low, even a "1080p" picture will show colour blocks and noise. Actual sharpness depends on bitrate, not just the resolution label.
Do I need 4K on a phone?
No. A phone screen is small, so 720p to 1080p looks great on most phones; the 4K difference is hard for the eye to tell, and it uses more network and data.
Is HDR always better?
Two conditions must both be met for it to work: the video itself is made in HDR, and your screen supports HDR. Miss either one and the HDR label means nothing.