VidPikMedia workbench
Video formats explained: MP4, WebM, MKV, MOV and more
A filename tells you the container. It does not tell you everything needed to play the video.
Container versus codec
Think of the container as a package holding video, audio, subtitles and timing information. A codec describes how one of those streams is encoded. For example, an MP4 file might contain H.264 video and AAC audio, or a different combination entirely.
| Container | Extension | Typical context | What to check |
|---|---|---|---|
| MP4 | .mp4 | A broadly used container. H.264 video with AAC audio is a practical starting point for sharing. | Check the actual codec and profile; MP4 can also hold less widely supported streams. |
| WebM | .webm | Often used for web delivery with VP8, VP9 or AV1 video and Vorbis or Opus audio. | Older devices may have limited hardware decoding. |
| MKV | .mkv | A flexible container that can hold multiple tracks and subtitles. | The player must support both the container and each selected stream. |
| MOV | .mov | Common in camera and editing workflows. | The codec may be H.264, HEVC, ProRes or another format; large editing files are not ideal for every phone. |
| AVI | .avi | A legacy container still found in older video collections. | An AVI extension alone says very little about whether a modern phone can decode it. |
| M4V | .m4v | Commonly associated with MPEG-4 video files. | Protected files require an authorized playback path. Renaming does not remove protection. |
| 3GP | .3gp | A container associated with mobile video and older handsets. | Check the codec, frame size and quality before converting or archiving. |
A useful compatibility checklist
- Find the video and audio codec in the file information.
- Check resolution, frame rate, profile and bit depth.
- Check the target player and device rather than only the operating system.
- Test a short sample before converting a whole library.
When to remux or transcode
Remuxing changes the package while retaining compatible streams. Transcoding re-encodes a stream and may reduce quality. Renaming .mkv to .mp4 does neither.
Use the compatibility checker or compare formats for your workflow.