What is MP4?
.mp4 · video/mp4
MP4 (MPEG-4 Part 14) is the most widely used video container format, supporting H.264/H.265 video, AAC audio, subtitles, and metadata.
Overview
MP4 (MPEG-4 Part 14) is a digital multimedia container format based on Apple's QuickTime format. It can store video, audio, subtitles, still images, and metadata in a single file. MP4 is the most widely supported video format across devices, browsers, and platforms. It typically uses H.264 (AVC) or H.265 (HEVC) for video compression and AAC for audio, providing excellent quality-to-size ratios for streaming and playback.
History
MP4 was developed by the Moving Picture Experts Group (MPEG) and published as ISO/IEC 14496-14 in 2003. It's based on Apple's QuickTime File Format (.mov) and the earlier MPEG-4 Part 12 (ISO base media file format). The format became the dominant video container with the rise of HTML5 video, smartphone cameras, and streaming services. H.264 codec support made MP4 the universal standard for video distribution.
File Structure
MP4 files are organized as a hierarchy of 'atoms' (also called 'boxes'). Key atoms include: ftyp (file type), moov (movie metadata with track info, timing, codec details), mdat (actual media data), and optional atoms for metadata (udta), chapters, and thumbnails. The moov atom can be at the beginning (fast-start/streaming-optimized) or end of the file.
Common Use Cases
- Web video streaming (HTML5)
- Social media video uploads
- Mobile device video recording
- Video-on-demand platforms
- Video editing and production
- Screen recordings and tutorials
- Digital signage and presentations
- Video archival and distribution
Advantages
- Universal device and browser support
- Excellent compression with H.264/H.265
- Supports multiple audio/subtitle tracks
- Streaming-optimized with fast-start
- Hardware acceleration widely available
- Good balance of quality and file size
Disadvantages
- H.265/HEVC may require licensing fees
- Not ideal for lossless video storage
- Container complexity can cause compatibility issues
- Large files for high-resolution content
- Editing requires re-encoding in most cases
- DRM can restrict playback
Frequently Asked Questions
What is an MP4 file?
An MP4 file is a multimedia container that stores video, audio, subtitles, and metadata. It's the most widely used video format, supported by virtually all devices, browsers, and media players. MP4 typically uses H.264 video and AAC audio codecs.
What is the difference between MP4 and MKV?
Both are container formats. MP4 has wider device/browser compatibility and is better for streaming. MKV supports more codecs, unlimited tracks, and chapters, making it preferred for high-quality video archival. MP4 is the standard for web; MKV for enthusiasts.
How do I reduce MP4 file size?
Reduce file size by lowering resolution, reducing bitrate, using a more efficient codec (H.265 instead of H.264), trimming unnecessary footage, or using tools like HandBrake or FFmpeg for re-encoding with optimized settings.
Can MP4 files contain subtitles?
Yes, MP4 supports embedded subtitle tracks in formats like SRT (as tx3g) and WebVTT. However, MKV offers more flexible subtitle support. Many players also support external subtitle files alongside MP4 videos.
Technical Details
- Extension
- .mp4
- MIME Type
- video/mp4
- Magic Bytes
- 00 00 00 xx 66 74 79 70 (ftyp box)
- Encoding
- H.264, H.265, AV1 (video); AAC, MP3, Opus (audio)
- Compression
- Lossy (typically)
- Specification
- ISO/IEC 14496-14:2003
- Max Size
- No practical limit