What is a container format?
A container format (also called a wrapper) packages together a video stream, audio stream(s), subtitles, chapter markers, thumbnails, and metadata into a single file. The container does not determine visual quality — that is determined by the codec. But it does determine what codecs can be stored, how many audio tracks are supported, and whether subtitles can be embedded.
Choosing the right container ensures maximum compatibility with your target device or platform, and avoids re-encoding just to switch formats.
Comparison table
| Format | Subtitles | Multi-Audio | Codec Support | Best For |
|---|---|---|---|---|
| MP4 | Limited | Yes | H.264, H.265, AV1, AAC | Streaming, sharing |
| MKV | Full | Unlimited | All codecs | Archives, home media |
| MOV | Yes | Yes | H.264, HEVC, ProRes | Apple editing |
| WebM | Basic | Limited | VP8, VP9, AV1, Opus | Web delivery |
| AVI | No | Limited | H.264, DivX, Xvid | Legacy only |
MP4 (.mp4) — The universal choice
MP4 (MPEG-4 Part 14) is the most compatible container across every browser, device, streaming service, and social media platform. It natively supports H.264, H.265, AV1, AAC audio, and basic subtitle tracks. The file overhead is minimal, making it ideal for distribution and online streaming. Drawback: embedded subtitle support is limited compared to MKV.
MKV (.mkv) — The media archive
Matroska (MKV) is an open, flexible container that supports virtually any video codec, unlimited audio tracks, multiple subtitle streams in any format (SRT, ASS, PGS), chapter markers, and file attachments. It is the preferred format for high-quality movie archives and content with multiple language tracks. BeeConvert preserves all MKV tracks during conversion. Caveat: less native support on smart TVs and mobile devices.
MOV (.mov) — Apple's native format
MOV is Apple's QuickTime container, used natively in macOS, iOS, and Final Cut Pro. It supports high-quality editing codecs including ProRes, ProRes RAW, and HEVC, along with multiple audio tracks and subtitle streams. MOV files work seamlessly in Apple workflows but have less consistent support on Android and older Windows systems without QuickTime installed.
WebM (.webm) — Built for the web
WebM is Google's open, royalty-free container designed for web delivery. It supports VP8, VP9, and AV1 video codecs alongside Opus and Vorbis audio. It is natively supported in all major modern browsers and is the only container that supports AV1 in most browser implementations. Optimal for HTML5 video elements and streaming without licensing concerns.
AVI (.avi) — The legacy format
AVI (Audio Video Interleave) was introduced by Microsoft in 1992. It has very poor support for modern codecs, no native subtitle embedding, limited multi-audio support, and produces large files. There is almost no modern use case where AVI is the right choice. If you have AVI files, convert them to MP4 or MKV using BeeConvert.
When to use which?
Use MP4 for sharing and streaming. MKV for subtitles and multiple audio tracks. MOV for Apple workflows. WebM for web-native delivery. Avoid AVI — convert to MP4 or MKV.