What is M3U8? Understanding Streaming Technology
Published on Dec 20, 2025
When you watch online videos or live streams on your phone, there's a key technology working behind the scenes β M3U8 protocol. As one of the most popular streaming formats today, M3U8 has become the de facto standard in the video industry.
What is M3U8
M3U8 is a text-based playlist file format, an extension of the M3U format. The "8" represents UTF-8 encoding, meaning M3U8 files support Unicode characters.
Technically, M3U8 files don't contain any audio/video data themselves. They're just "index files" or "playlists" that record segment URLs, durations, encoding info and other metadata.
π‘ Simple Analogy
Think of M3U8 as a book's table of contents. The TOC doesn't contain the actual content, but tells you where each chapter is. The video player is like a reader, using the TOC (M3U8) to find and play specific chapters (video segments).
M3U8 and HLS
When talking about M3U8, we must mention HLS (HTTP Live Streaming). HLS is a streaming protocol introduced by Apple in 2009, and M3U8 is the file format used to describe media playlists in HLS.
Simply put, HLS is a complete streaming solution that includes:
- β’ Video encoding: Converting raw video to H.264/H.265 formats
- β’ Video segmentation: Splitting long videos into small segments (usually .ts files)
- β’ Playlist: Using M3U8 files to index these segments
- β’ Transport: Transmitting via standard HTTP/HTTPS protocol
M3U8 File Structure
M3U8 files are plain text, using specific tags to describe media information:
#EXTM3U #EXT-X-VERSION:3 #EXT-X-TARGETDURATION:10 #EXT-X-MEDIA-SEQUENCE:0 #EXTINF:9.009, segment_0001.ts #EXTINF:9.009, segment_0002.ts #EXTINF:9.009, segment_0003.ts #EXT-X-ENDLIST
Key Tags Explained
| Tag | Meaning |
|---|---|
| #EXTM3U | File header, must be on first line |
| #EXT-X-VERSION | HLS protocol version |
| #EXT-X-TARGETDURATION | Maximum segment duration (seconds) |
| #EXTINF | Actual segment duration |
| #EXT-X-ENDLIST | End of playlist marker |
Adaptive Bitrate Streaming
One of M3U8's most powerful features is Adaptive Bitrate Streaming (ABR). The player automatically selects the best version based on current network conditions:
#EXTM3U #EXT-X-STREAM-INF:BANDWIDTH=800000,RESOLUTION=640x360 360p/playlist.m3u8 #EXT-X-STREAM-INF:BANDWIDTH=1400000,RESOLUTION=842x480 480p/playlist.m3u8 #EXT-X-STREAM-INF:BANDWIDTH=2800000,RESOLUTION=1280x720 720p/playlist.m3u8 #EXT-X-STREAM-INF:BANDWIDTH=5000000,RESOLUTION=1920x1080 1080p/playlist.m3u8
- β’ Good network: Auto-switch to HD quality
- β’ Poor network: Auto-lower quality to ensure smooth playback
- β’ Network recovers: Gradually improve quality
M3U8 Use Cases
π¬ Video on Demand
Streaming platforms like Netflix, YouTube, etc.
πΊ Live Streaming
Twitch, YouTube Live, and other platforms
π‘ IPTV
Internet TV services transmitting channels via M3U8
π Online Education
Video courses on e-learning platforms
Why is M3U8 So Popular?
β HTTP-based
No special servers needed, works with standard web servers and CDNs
β Firewall Friendly
Uses standard 80/443 ports, not blocked by corporate firewalls
β Wide Device Support
Native iOS/macOS support, Android and browsers work via hls.js
β Encryption Support
Built-in AES-128 encryption to protect video content
Summary
M3U8, as a core component of the HLS streaming protocol, has become the mainstream standard for online video transmission due to its flexibility, compatibility, and reliability. Whether for VOD, live streaming, or IPTV services, M3U8 plays an irreplaceable role.