Upscaling
Upscaling, in playback analytics, is when the player stretches a video rendition to fill a screen larger than the video's own resolution. A 720p stream on a 4K TV is heavily upscaled and looks soft. Analytics report it as the percentage of watch time spent upscaled and the maximum stretch reached.
Why it matters
Upscaling is the hidden reason viewers on large TVs say the picture looks soft, and they are often the highest-value subscribers. Measuring it shows whether the fix is a higher rung in the encoding ladder, better delivery to that device, or a less cautious player.
How it works
- The player knows the resolution of the rendition it is playing, such as 1280 x 720.
- It also knows the size of the area the video is drawn into on screen.
- When the display area is larger, the video is stretched, and the time spent that way is logged.
- Reports show the share of watch time upscaled and the largest stretch reached in the view.
Does upscaling reduce video quality?
Upscaling does not add detail, so stretched video looks softer than video delivered at the screen's native resolution. Modern TVs and browsers upscale smoothly, so mild upscaling is barely visible. Heavy upscaling, such as 480p on a 4K TV, is clearly blurry. The fix is to deliver a higher rendition, not to rely on the device.
Upscaling vs downscaling: which is worse?
Upscaling is worse for viewers, because the picture looks soft. Downscaling is worse for budgets, because you pay to deliver pixels that are thrown away. A healthy service keeps both low by matching renditions to the screen sizes its viewers actually use.
Where it's used
OTT services track upscaling by device type, because high upscaling on TVs means the encoding ladder needs a higher rung or the adaptive logic is too cautious.
Where it usually goes wrong, and how FastPix handles it
Teams rarely compare delivered resolution with screen size, so heavy upscaling on TVs looks fine in bitrate reports while viewers see a soft picture.
Upscale percentage and max upscale percentage are reported for each view in FastPix Video Data, and both feed the render quality score. Breaking them down by device type shows where a higher rendition is needed. So your team can show which TV models get a stretched picture and target the fix there.
By the numbers
- 4K UHD (3840 x 2160) has exactly double the horizontal and vertical resolution of 1080p, for four times as many pixels. (4K resolution (Wikipedia))
