Video Quality

What is good video quality and what is bad?

Resolution

Resolution of the video is number of pixels in height and in width.

The number 640x480 means that the image has 640 pixel in width and 480 in height. The Common name is related to the smaller number - the height of the image.

Resolution Type	Common Name	Aspect Ratio	Pixel Size
SD (Standard Definition)	480p	4:3	640 x 480
HD (High Definition)	720p	16:9	1280 x 720
Full HD (FHD)	1080p	16:9	1920 x 1080
QHD (Quad HD)	1440p	16:9	2560 x 1440
2K video	1080p	1:1.77	2048 x 1080
4K video or Ultra HD (UHD)	4K or 2160p	1:1.9	3840 x 2160
8K video or Full Ultra HD	8K or 4320p	16∶9	7680 x 4320

The visual representation of the image size. By the way, it doesn’t mean that 8k TV is bigger that 4k TV, as the pixels could have different size. The resolution is just a number of pixels.

For image - the more pixels we have, the more detailed picture is, as we could see very small details. But it also means that we will have bigger file to store all this information about each pixel.

Camera resolution

 Is more Mega Pixels means better camera? Of course not.

My phone has 50MP image module. My Sony Camera has only 20MP image sensor. But the phone sensor has 72.2 mm² area, and Sony 366.60 mm². The Sony has less number of pixels, but they are much bigger is size. If we take photo in low light environment, the image from Sony will have much less noise, as it has bigger size and received more light. (It is simplified, as in real life the phone take a lot of photos, and make the image look better using AI. )

Does phone saves photos at full resolution? It could but don’t, as it will require more space, so it automatically reduces the resolution to 3072x4080=12  533 760=12.5MP. At least my Pixel 8.

Bitrate

Lets return to video.

The video has additional parameter - bitrate. In the simplest terms, bitrate is the amount of data used to encode a single second of video or audio.

The video with higher bitrate, for example 20Mbit will look much better that with 5Mbit bitrate at the same resolution.

This is the recommendation from YouTube for HDR video:

Type	Video Bitrate, Standard Frame Rate (24, 25, 30)	Video Bitrate, High Frame Rate (48, 50, 60)
8K	100 - 200 Mbps	150 to 300 Mbps
2160p (4K)	44–56 Mbps	66–85 Mbps
1440p (2K)	20 Mbps	30 Mbps
1080p	10 Mbps	15 Mbps
720p	6.5 Mbps	9.5 Mbps

The bitrate is also a internet speed which you need to stream your video. For example if you want to stream YouTube live at 1080p you will need 10Mbit stable internet speed.

H.264 (AVC)

• Acceptable: 20–30 Mbps (may show compression in motion-heavy scenes)
• Good: 35–50 Mbps (sharper quality)
• High: 50–100 Mbps (professional-level or archival)

H.265(HEVC)

• Streaming Quality: 15–25 Mbps (used by Netflix, Amazon Prime)
• Good: 25–40 Mbps (great quality-to-size ratio)
• High: 50–100+ Mbps (UHD Blu-ray tops out at 128 Mbps)

With a decent Wi-Fi 6 router, you could have at 100-150 Mbps at far range with 2.4 GHz, and it is why better to use 5GHz or wired connection for your TV to watch the movie in 4k at high quality.

Links

• support.google.com
• wiisfi.com