The extension is only the envelope.
A video file combines several choices. Read them separately before deciding what to preserve.
| Property | What it describes | Example |
|---|---|---|
| Container | The package holding video, audio and other streams. | MP4, MOV, Matroska |
| Video codec | The representation or compression of the picture. | H.264, HEVC, AV1 |
| Frame dimensions | The width and height in pixels. | 1920 × 1080 |
| Frame rate | The timing of successive pictures. | 25 frames per second |
Preserve before converting
A convenient viewing copy and an archival original serve different purposes. A smaller export may be useful for sharing, but keep the source material if you expect to edit again.
Remember the sound
A file may contain multiple audio tracks, separate microphone channels, subtitles or timecode. Check these before a conversion. A picture that looks correct does not guarantee that every supporting stream survived.
Changing a filename extension does not convert the media inside it. Inspect the file with a media information tool rather than guessing from its name.