The short version
- A video file is a container (like MP4 or WebM) holding video and audio encoded with codecs (like H.264 or VP9).
- MP4 with H.264 video and AAC audio is the most widely compatible combination.
- WebM is an open format that browsers and YouTube handle well, but some phone apps don't accept it.
- Bitrate controls quality and file size; resolution controls sharpness.
Containers and codecs
A video file has two layers, and mixing them up causes most of the confusion:
- The container is the file format — the box. It's what the file extension shows:
.mp4,.webm,.mov,.mkv. It holds the video, the audio and information about them. - The codecs are how the video and audio inside are compressed. Common video codecs are H.264 (also called AVC), H.265 (HEVC), VP8, VP9 and AV1. Common audio codecs are AAC and Opus.
This is why two .mp4 files can behave differently: one might contain H.264 (plays almost everywhere) and another H.265 (plays on newer devices but not all browsers or older computers).
MP4 vs WebM
| MP4 | WebM | |
|---|---|---|
| Typical codecs | H.264 or H.265 video, AAC audio | VP8, VP9 or AV1 video, Opus audio |
| Compatibility | Plays almost everywhere: phones, computers, TVs, editing apps and social platforms | Plays in modern web browsers; YouTube accepts it; some phone apps and older software don't |
| Best for | Sharing, uploading and sending to anyone | Websites and browser-based workflows |
| Licensing | Some codecs involve patent licensing (handled by device makers) | Open and royalty-free |
If you're unsure, use MP4. It's the safest choice for posting to social media and sending to other people.
Bitrate and quality
Bitrate is how much data is used per second of video, usually measured in megabits per second (Mbps). Higher bitrate means more detail and bigger files; lower bitrate means smaller files and, eventually, blocky artefacts — especially in fast motion, confetti, water and fine textures.
- Social platforms re-compress everything you upload, so uploading at a sensible quality is enough; enormous files rarely look better after the platform's own compression.
- If your upload looks blocky, the problem is often low light and noise in the original footage, which compresses badly. Better lighting helps more than a higher export bitrate.
Resolution and frame rate
Resolution is the number of pixels (for example 1920 × 1080); frame rate is frames per second (for example 30 fps). Most platforms accept a wide range of both. Our sizes cheat sheet lists the recommended resolution for each platform, and explains aspect ratio and frame rate in more detail.
Exporting from VDOAPP
VDOAPP creates your video inside your browser, using the browser's own built-in video encoder. That affects the format you get:
- MP4 — in browsers that support recording MP4, such as recent versions of Chrome, Edge and Safari.
- WebM — in browsers that don't, such as Firefox.
- Resolution: 720p on the shorter side — for example 720 × 1280 for vertical video or 1280 × 720 for horizontal.
- Speed: export happens in real time, so a one-minute video takes about a minute. Keep the tab open and visible.
- Single frames can be saved as PNG images with the Snapshot button.
.webm, open the editor in Chrome or Edge and export again.Upload troubleshooting
| Problem | Likely cause | What to try |
|---|---|---|
| "File type not supported" | The app doesn't accept the container (often WebM or MKV). | Export as MP4 — in VDOAPP, use Chrome or Edge. |
| Plays on computer, not on phone | Unsupported codec, often H.265 or VP9 on older devices. | Re-export as MP4 with H.264. |
| No sound after upload | Unsupported audio codec, or the audio was muted in the edit. | Check clip volumes; re-export as MP4. |
| Blocky, smeary video | Low light, noise, or heavy platform compression. | Film in better light; avoid heavy grain effects; upload at 1080p where possible. |
| Black bars or awkward crop | Aspect ratio doesn't match the platform. | Set the right canvas shape before exporting. |
| Very long upload | Large file or slow connection. | Use Wi-Fi; shorter videos and 720p–1080p files upload faster. |
Platforms update their supported formats from time to time, so if an upload fails, check the platform's current help page for accepted file types.
Got an iPhone video that won't open? See how to edit iPhone videos (HEVC and MOV) and our troubleshooting guide.
Need a smaller file? Read how to reduce video file size.