Video Formats and Codecs Explained
MP4, MOV, H.264, HEVC, bitrate, 1080p… Video comes with a lot of jargon. This guide explains what each term means in plain language and how it affects file size and compatibility.
Container and codec: two different things
Every video file has two layers:
- The container is the file format, the box. It's what the file extension shows:
.mp4,.mov,.mkv,.webm,.avi. - The codec is how the video and audio inside the box are compressed: H.264, HEVC, VP9, AV1 for video; AAC, Opus, MP3 for audio.
The same codec can live in different containers. An iPhone video and a Windows screen recording may both use H.264 even though one is .mov and the other is .mp4. Whether a video plays depends mostly on the codec, while the container mostly decides which apps recognise the file.
Common containers
| Container | Where you'll see it | Notes |
|---|---|---|
| MP4 | Phones, cameras, the web | The most widely supported container |
| MOV | iPhone, Mac, some cameras | Apple's QuickTime format; plays best on Apple devices |
| MKV | Downloads, recordings | Very flexible; not supported by every app or TV |
| WebM | Browsers, screen recorders | Designed for the web; usually VP9 or AV1 with Opus audio |
| AVI, WMV, FLV | Older Windows and web videos | Outdated; convert to MP4 for modern devices |
Common video codecs
| Codec | Also called | Efficiency | Compatibility |
|---|---|---|---|
| H.264 | AVC | Good | Plays on practically everything |
| HEVC | H.265 | 30–50% smaller than H.264 | Apple devices, recent PCs and phones; not universal |
| VP9 | — | Similar to HEVC | Browsers and Android; less so elsewhere |
| AV1 | — | Smallest | Newest devices and browsers |
H.264 is the safe choice when you don't know where a video will be played. That's why the Video Compressor always outputs H.264 in an MP4 container with AAC audio.
Bitrate: what decides the file size
Bitrate is the amount of data used per second of video, measured in kilobits or megabits per second (kbps, Mbps). File size is simply bitrate multiplied by duration:
8 Mbps × 60 seconds = 480 megabits = 60 MB
Higher bitrate means more detail and a bigger file. But the same bitrate looks different depending on the codec, the resolution and the content: a talking head needs far less than a fast football match or a video full of grain.
Typical bitrates for good-looking H.264 at 30 fps:
| Resolution | Typical bitrate | One minute is about |
|---|---|---|
| 480p | 1–1.5 Mbps | 8–11 MB |
| 720p | 2.5–4 Mbps | 19–30 MB |
| 1080p | 5–8 Mbps | 38–60 MB |
| 4K | 15–35 Mbps | 110–260 MB |
Resolution and frame rate
Resolution is the number of pixels in each frame:
- 480p: 854 × 480
- 720p (HD): 1280 × 720
- 1080p (Full HD): 1920 × 1080
- 4K (UHD): 3840 × 2160
For portrait phone videos, the numbers are swapped (for example 1080 × 1920), but they're still called 1080p.
Frame rate is the number of frames per second. 24 fps is used for films, 30 fps for most video, and 60 fps for sport, games and slow motion. More frames need more data.
Audio codecs
Audio is a small part of a video's size. AAC is the standard for MP4 files and plays everywhere; Opus is common in WebM. Speech sounds good at 64–96 kbps; music at 128 kbps or more.
Which format should you use?
- Sharing with anyone, anywhere: MP4 with H.264 and AAC.
- Saving space on Apple devices: HEVC, but convert to H.264 MP4 before sharing with others.
- Uploading to a video platform: upload the original; the platform re-encodes it anyway.
- Embedding on your own website: MP4 (H.264) for compatibility, optionally WebM (VP9 or AV1) for smaller files.
Summary
- The container is the file type; the codec is the compression inside it.
- H.264 in MP4 plays everywhere; HEVC and AV1 are smaller but less compatible.
- Bitrate × duration = file size, so lowering bitrate or resolution is how compression works.