Dropped frames
Dropped frames are video frames the device failed to display in time and skipped, which viewers see as stutter or jerky motion. The network can be perfect and frames still drop, because the cause is usually a device or browser that cannot decode the video fast enough.
Why it matters
Stutter makes fast action hard to follow and makes an app feel cheap, even when the stream never buffers. Because dropped frames come from the device, network fixes will not help. Knowing which devices drop frames tells teams where to cap resolution or frame rate.
How it works
- The device decodes each frame of video and must draw it on screen at a set moment.
- If decoding or drawing runs late, the device skips that frame to stay in time with the audio.
- Browsers and native players keep a running count of skipped frames for each video.
- Analytics tools read that count and report it per view, by device, browser and rendition.
What causes dropped frames when streaming?
Dropped frames are mostly caused by a device that cannot decode or display video fast enough. High resolutions, 60 fps content, codecs without hardware decoding support, busy processors and heavy page scripts are common causes. Network problems usually show up as buffering instead, so the fix is often a lower rendition or a different codec for that device.
Dropped frames vs buffering: what is the difference?
Buffering means the player ran out of downloaded video and paused, which is usually a network problem. Dropped frames mean the video was there but the device skipped frames while playing, which is usually a device problem. Buffering looks like a spinner; dropped frames look like jerky motion while the picture keeps moving.
Where it's used
Live sports streamers and game streaming platforms track dropped frames by device model, since fast motion at 60 frames per second exposes weak phones and older smart TVs.
Where it usually goes wrong, and how FastPix handles it
Teams often blame the network for stutter and change CDNs, when the real cause is devices that cannot decode the chosen rendition in time.
Dropped frame counts come straight from the player for every view in FastPix Video Data. It can be broken down by device type, model, OS and browser. That stops a team from paying to switch CDNs for a device problem, and shows exactly which models need a lower resolution or frame rate.
By the numbers
- Web browsers expose dropped frames through the VideoPlaybackQuality interface, whose droppedVideoFrames value counts frames dropped rather than displayed since the media was loaded. (VideoPlaybackQuality: droppedVideoFrames property (MDN))
