MP4 File Format (MPEG-4 Part 14)
MP4 is the most widely used video container format in the world, standardized as MPEG-4 Part 14. It can contain video streams (typically H.264 or H.265), audio streams (AAC, MP3), subtitles, and metadata in a single file. MP4 is the default video format for virtually every platform: YouTube, social media, streaming services, smartphones, and web browsers all natively support MP4 playback. The format uses the ISO Base Media File Format (ISOBMFF) container, which supports streaming via progressive download and adaptive bitrate delivery. MP4 with H.264 video and AAC audio is considered the universal video format with the broadest hardware and software support.
Quick Facts
- Extension: .mp4
- MIME Type: video/mp4
- Category: video
Advantages
- Universal playback support across all devices and platforms
- Excellent compression with H.264 or H.265 codecs
- Supports multiple audio tracks and subtitles
- Streaming-friendly with moov atom at start
- Hardware decoding support on virtually all modern devices
Disadvantages
- H.264 and H.265 codecs have patent licensing requirements
- Not ideal for lossless video archival
- Some older H.264 profiles limit features
- Container format complexity can cause compatibility edge cases
- Re-encoding always introduces some quality loss
Common Use Cases
- Online video sharing and social media uploads
- Video streaming and progressive download
- Smartphone and camera video recording
- Video editing project exports
- Embedded website video content
Technical Details
MP4 uses the ISO Base Media File Format, organizing data into nested boxes (atoms). The "moov" atom contains metadata, track information, and timestamps, while "mdat" holds compressed media data. For streaming, the moov atom is placed at the file start (fast-start). H.264 (AVC) divides frames into macroblocks with intra and inter prediction, using CABAC or CAVLC entropy coding. H.265 (HEVC) uses coding tree units up to 64x64 pixels for approximately 50% better compression at equivalent quality. MP4 supports multiple tracks, chapters, and fragmented MP4 (fMP4) for adaptive streaming.
Frequently Asked Questions about MP4
Is MP4 the best video format?
For general compatibility, yes. MP4 with H.264 video and AAC audio plays on virtually every device. For cutting-edge compression, MP4 with H.265 or AV1 offers better quality per byte.
Can MP4 contain audio only?
Yes. An MP4 file can contain only an audio stream without video. M4A is essentially an audio-only MP4 with a different extension.
How do I reduce MP4 file size?
Lower the resolution, reduce the bitrate, use a more efficient codec (H.265 instead of H.264), or trim unnecessary portions. FileChange can handle video conversion in your browser.
What is the difference between MP4 and MOV?
Both use the same ISOBMFF container format. MOV is Apple QuickTime variant, while MP4 is the ISO standard. In practice, they are very similar and often interchangeable.
Can I extract audio from an MP4 video?
Yes. Converting MP4 to MP3 extracts just the audio track. FileChange does this using FFmpeg.wasm directly in your browser.