Render quality score
A render quality score measures how sharp the picture looked relative to what the screen could show. It drops when the player has to stretch a low resolution video to fill a large screen (upscaling) or when quality keeps switching. A high score means viewers mostly saw video at or above their screen's resolution.
Why it matters
Viewers pay for HD and 4K and notice when the picture looks soft. A low render quality score shows where spending on encoding and delivery is not reaching the screen, often on large TVs. Fixing it can reduce churn among the most valuable subscribers without raising delivery costs everywhere.
How it works
- The player compares the resolution of the video being played with the size of the area showing it.
- Time spent stretching a smaller video to fill a bigger area is logged as upscaling.
- Each switch between quality levels during the view is also counted.
- Less upscaling and fewer quality switches produce a higher score; heavy stretching or constant switching lowers it.
Why does my video look blurry on a TV?
Video looks blurry on a TV when the player shows a rendition well below the screen's resolution and stretches it to fit. That happens when the encoding ladder has no high rung, when the network cannot sustain one, or when the player's adaptive logic stays on a low quality too long. Checking upscaling by device type usually shows which of these is the cause.
Render quality vs bitrate: which should I track?
Track both, but render quality tells you more about what viewers saw. Bitrate shows how much data was delivered, yet a high bitrate on a phone can be wasted while a modest one on a 4K TV looks soft. Render quality compares the picture with the screen, so it captures whether the delivered quality matched the device.
Where it's used
OTT services use the render quality score to find titles or devices where viewers get a soft picture, often because the encoding ladder lacks a rung that matches big-screen TVs.
Where it usually goes wrong, and how FastPix handles it
Teams often judge picture quality by the top rendition they encode, not by what devices actually display, so soft playback on large screens goes unnoticed.
Maximum upscaling, upscaling percentage and how often the resolution changed make up the render quality score in FastPix Video Data. It carries a 0.330 weight in the QoE score. Your team can see which devices get a soft picture and focus fixes on those viewers rather than on everyone.
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))
