What the comparison shows.

The two players

On the left, the uncompressed.io player streams the uploaded export. On the right, the official Vimeo player plays the same film. The comparison requests Vimeo’s 2160p quality and waits for confirmation and both players’ buffers before synchronized playback. If 4K is unavailable, it offers a retry.

Playback starts muted. Connection speed, browser and device can affect buffering and synchronization. Loading posters are not comparison frames.

What the Mbps readings mean

The UC bitrate is calculated from the original file’s encoded video samples at the playback position. The Vimeo number comes from a 3840 × 2160 AVC/H.264 reference at 24 fps, captured on September 17, 2026 and synchronized to the player’s position. Vimeo’s SDK does not expose the actual bitrate of its current adaptive stream.

The readings represent video bits per second of content, excluding audio and container overhead. They are not network-throughput readings. A higher bitrate alone is not a visual-quality score.

Measurement window

1 second of video; the final partial window retains its actual duration.

Reference verification

863 source and output video packets compared by byte size and SHA-256. Encoded packets are identical.

Reproduce the measurement

1. Use the same file and identify its resolution, codec and frame rate. Record the export settings for any new comparison.
2. Read timestamps, durations and packet sizes for the video track, excluding audio.
3. Group bytes into one-second windows from the first sample. Split a sample proportionally if it crosses a window boundary. Multiply bytes by eight, then divide by the window duration and one million to obtain Mbps.
4. Compare at matching playback positions and inspect the picture. Document the browser, device, selected quality and connection separately.

ffprobe -v error -select_streams v:0 -show_packets -show_entries packet=pts_time,duration_time,size -of json film.mp4

The 100 Mbps / 22 Mbps chart

It illustrates a 100 Mbps 4K H.264 export against Vimeo’s published 4K H.264 delivery maximum of 22 Mbps. Actual output can be lower. This chart does not measure the film playing in the players above.

The frame comparison

The published frames come from the existing UC demonstration. Fit mode scales both sides equally; 100% uses their source pixels. Inspect these specific exports for grading, highlights, shadows, banding and grain. Results depend on the file and encoding.