Video Info Checker
Read a video's container, codec, resolution, duration and bitrate — with a straight answer about frame rate.
Convert with this tool
or choose a file from your device — it is processed in this tab and never uploaded
Accepted: MP4, MOV, MKV, WebM, AVI and other containers
Files stay on your device. There is no upload, no queue and no watermark, so a conversion works even with the network switched off after the page has loaded.
Supported formats & processing
| Accepted input | MP4, MOV, MKV, WebM, AVI and other containers |
|---|---|
| Produced output | An inspection report with a downloadable JSON file |
| Processing | Web Audio API + canvas + native JavaScript encoders |
| Upload required | No — the file is read locally and never transmitted |
How to use this tool
- Add the video fileThe container structure is walked to find the codec identifiers.
- Read the resolution and durationThese are confirmed by decoding the video metadata.
- Check the bitrateCalculated from the file size and the decoded duration.
- Note the frame rate rowIt reports honestly that the value is not exposed to JavaScript.
- Download the JSON reportEverything found is exported for your records.
About this tool
Video inspection is genuinely harder than audio inspection in a browser, because there is no built-in demuxer. What is available is the container header, which for MP4 and Matroska contains most of what you need, and the HTML video element's metadata, which gives resolution and duration.
This checker combines both: it walks the MP4 box structure or the Matroska EBML tree to find the codec identifiers and dimensions, and it opens the file in a video element to confirm the decoded resolution and duration. Frame rate is reported as unavailable, because no browser API exposes it — the stts or default-duration box would have to be parsed, which this tool does not pretend to do.
Features
- MP4 box walking to find the real sample entry codecs
- Matroska EBML parsing for CodecID, width and height
- Decoded resolution and duration confirmed from the video element
- Overall bitrate calculated from the real file size
- Honest reporting of what a browser cannot read
- Downloadable JSON report
Frequently asked questions
Why can the tool not show the frame rate?
The HTML video element does not expose it, and there is no browser API that reports it. The value lives in the MP4 stts box or the Matroska default-duration element, which requires a full container demuxer. Rather than guess from a byte pattern, the tool says it is unavailable.
How do I find out a video's frame rate?
Use a desktop tool such as ffprobe, which reads the container properly: ffprobe -v error -select_streams v:0 -show_entries stream=r_frame_rate -of csv=p=0 file.mp4. Alternatively, convert it to a known rate with the FPS converter.
What are sample entry types?
Four-character codes inside the MP4 stsd box that identify the codec of each stream — avc1 for H.264, hvc1 for HEVC, mp4a for AAC, av01 for AV1. They are the most reliable codec evidence available from a header.
Can I check a video without uploading it?
Yes. The container is read locally with the File API and the metadata comes from a locally created object URL. Nothing is transmitted.