OneTaskBy Tim King · Updated
Video Info Inspector
Resolution, Frame Rate, Bitrate and Duration
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How the Video Info Inspector works
Drop a clip into this video info inspector to see what is inside it: the container, resolution, aspect ratio, measured frame rate, exact duration, average bitrate and whether it carries sound. Download saves the same facts as a text or JSON report. The file is read by your browser and is never uploaded.
File names and thumbnails say little about a video. A clip called final_1080p.mp4 may be 720p, a screen recording may run at a variable frame rate, and a phone export may be twice the bitrate an upload form allows. Checking the facts before you edit or send a file avoids a failed upload or a render with the wrong settings.
What the video info inspector reports
| Line | Where it comes from |
|---|---|
| Container | The file extension, such as MP4, MOV, WebM or MKV |
| MIME type | The type your operating system reports for the file |
| Resolution | The decoded picture size, after any phone rotation flag |
| Aspect ratio | Width and height reduced to whole numbers, plus the decimal |
| Frame rate | Measured from the frames your browser presents during a short play |
| Audio | Whether the browser decoded any sound from the file |
| Average bitrate | File size in bits divided by duration, picture and sound together |
How the frame rate is measured
Most containers store a nominal frame rate, but browsers do not expose it. The inspector plays the first two seconds muted and records the media timestamp of every frame shown, using the requestVideoFrameCallback API. It takes the median gap between frames and snaps the result to the nearest broadcast rate, such as 23.976, 25, 29.97 or 60, if it is within 1.5%. When no standard rate is close, the clip is probably variable frame rate, which is common in phone footage and screen recordings, and the line says so.
Tips and pitfalls
Bitrate is an average. Modern encoders spend more bits on busy scenes, so a clip averaging 8 Mbit/s may peak far higher. Upload limits usually refer to the average, which is what this shows.
Rotated phone clips. A portrait video stored as landscape with a rotation flag is reported in the orientation you see, because the browser applies the flag before decoding.
Unknown codecs. If the browser cannot decode the file, for example HEVC in Firefox or ProRes anywhere, no figures can be read. Try Chrome or Safari, or convert the clip first.
How to read the result
Compare the resolution and frame rate with your project or upload settings. If the frame rate says variable, convert the clip to a constant rate before editing to keep sound in sync.
FAQ
How do I find the frame rate of a video?
Drop the file here and wait two seconds. The inspector plays the start of the clip silently, times every frame and reports the rate, snapped to a standard value such as 25 or 29.97 fps when the measurement is close to one.
Why is the bitrate higher than my export setting?
The figure includes the audio track and the container overhead, and it is averaged over the whole file. Short clips also carry a fixed amount of header data, which adds noticeably to the bitrate of a clip only a few seconds long.
Can it read MOV and MKV files?
It can read any file your browser can decode. Chrome plays most MOV files with H.264 video and many MKV files with H.264 or VP9. Safari adds HEVC. ProRes and other editing codecs cannot be decoded by any browser.
Is my video uploaded to read its details?
No. The browser opens the file from your disk and reads its details locally. Nothing is sent to a server, so you can inspect private or unreleased footage without it ever leaving your computer.
See also: all Video & Screen tools, Images, Audio, PDF, SVG, Simulations & Screensavers, Generative Art, Chart Makers, 3D Model Viewers, Drawing Pads, Mockups & 3D Making, Diagram Makers, 3D Science, Tracker Music.
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