What the numbers mean
- Codec — how the picture is compressed. avc1 is H.264 (plays everywhere), hvc1 is H.265 (smaller, pickier).
- Bitrate — data per second. It, not resolution, is what mostly decides file size and visible quality.
- Keyframes — complete pictures you can seek to. Sparse keyframes mean choppy scrubbing.
Useful before you convert
Checking the source bitrate first tells you whether compressing is even worth it: re-encoding a 1 Mbps clip at 2.5 Mbps only makes the file bigger. Our video compressor caps the target automatically, but knowing the number helps you pick.
What the metadata tells you
Codec, resolution, frame rate, bitrate, duration, audio channels and sample rate, read from the file headers rather than guessed from the extension. A file named .mp4 can contain almost anything, and this is how you find out what.
Most useful when something will not play or an upload is rejected: the answer is usually an unexpected codec, a variable frame rate, or a resolution above what the destination accepts.
Frequently asked questions
Is my file uploaded?
No. Everything is parsed and processed inside your browser — the file never leaves your device.
Why will my video not play somewhere?
Usually the codec rather than the container. An .mp4 holding H.265 will not play where only H.264 is supported, and the extension gives no clue.
Is the file uploaded to read it?
No — only the header is read, in your browser, so even a very large file is inspected instantly.
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