CMAF Streaming - Ant Media Server

Overview

CMAF (Common Media Application Format) is a standardized media format that enables efficient delivery of streaming content. It uses fragmented MP4 (fMP4) containers that can be packaged for both HLS and DASH, reducing storage and encoding costs.

Key Benefits

Unified workflow: Single encode for HLS and DASH
Reduced storage: One set of media files for multiple protocols
Lower latency: Smaller chunks enable faster delivery
Better codec support: Native support for HEVC, AV1, VP9
Efficient: Reduced CDN costs and bandwidth usage
Standards-based: ISO BMFF/MP4 format

How CMAF Works

CMAF uses fragmented MP4 (fMP4) containers that can be delivered via:

HLS with fMP4: Apple devices, browsers
DASH: Android, browsers, smart TVs
MSE (Media Source Extensions): Modern browsers

Enabling CMAF in Ant Media Server

Configuration

CMAF is enabled through HLS with fMP4 segments:

# Enable HLS with CMAF/fMP4
settings.hlsMuxingEnabled=true
settings.hlsSegmentType=fmp4

# Enable DASH (uses same CMAF segments)
settings.dashMuxingEnabled=true

# Segment duration (shorter for low latency)
settings.hlsTime=2
settings.dashSegDuration=2s

# Fragment duration (sub-segment chunks)
settings.dashFragmentDuration=0.5s

Publishing for CMAF

# Publish via RTMP
ffmpeg -re -i input.mp4 \
  -c:v libx264 -preset veryfast -b:v 2500k \
  -c:a aac -b:a 128k \
  -f flv rtmp://your-server.com/WebRTCAppEE/stream123

# Access as:
# HLS: https://your-server.com:5443/WebRTCAppEE/streams/stream123.m3u8
# DASH: https://your-server.com:5443/WebRTCAppEE/streams/stream123.mpd

Playing CMAF Streams

HLS with fMP4 (CMAF)

<script src="https://cdn.jsdelivr.net/npm/hls.js@latest"></script>
<video id="video" controls width="100%"></video>

<script>
  const video = document.getElementById('video');
  const hlsUrl = 'https://your-server.com:5443/WebRTCAppEE/streams/stream123.m3u8';
  
  if (Hls.isSupported()) {
    const hls = new Hls({
      enableWorker: true,
      lowLatencyMode: true,
      backBufferLength: 90
    });
    
    hls.loadSource(hlsUrl);
    hls.attachMedia(video);
    
    hls.on(Hls.Events.MANIFEST_PARSED, () => {
      video.play();
    });
  }
</script>

DASH (CMAF)

<script src="https://cdn.dashjs.org/latest/dash.all.min.js"></script>
<video id="video" controls width="100%"></video>

<script>
  const url = 'https://your-server.com:5443/WebRTCAppEE/streams/stream123.mpd';
  const player = dashjs.MediaPlayer().create();
  
  player.initialize(document.getElementById('video'), url, true);
  
  player.updateSettings({
    streaming: {
      lowLatencyEnabled: true,
      liveDelay: 3,
      delay: {
        liveDelay: 3
      },
      buffer: {
        fastSwitchEnabled: true
      }
    }
  });
</script>

Low Latency CMAF (LL-DASH / LL-HLS)

Configuration for Ultra-Low Latency

# Enable low latency modes
settings.lLDashEnabled=true
settings.lLHLSEnabled=true

# Short segments
settings.hlsTime=2
settings.dashSegDuration=2s

# Small fragments (chunks)
settings.dashFragmentDuration=0.2s
settings.hlsPartTargetDuration=0.2

# Target latency
settings.targetLatency=3s

# Streaming mode
settings.dashHttpStreaming=true

LL-DASH Player Configuration

const player = dashjs.MediaPlayer().create();

player.updateSettings({
    streaming: {
        lowLatencyEnabled: true,
        liveDelay: 3,  // Target 3 second latency
        liveCatchup: {
            enabled: true,
            mode: 'liveCatchupModeDefault'
        },
        delay: {
            liveDelay: 3,
            liveDelayFragmentCount: NaN,  // Use time-based delay
            useSuggestedPresentationDelay: false
        },
        buffer: {
            fastSwitchEnabled: true,
            flushBufferAtTrackSwitch: false,
            reuseExistingSourceBuffers: true,
            bufferTimeDefault: 12,
            bufferTimeAtTopQuality: 12,
            bufferTimeAtTopQualityLongForm: 12
        }
    }
});

CMAF Structure

File Organization

streams/
├── stream123.m3u8              # HLS master playlist
├── stream123.mpd               # DASH manifest
├── stream123_init.mp4          # Initialization segment
├── stream123_000000000.m4s     # Media segment 0
├── stream123_000000001.m4s     # Media segment 1
├── stream123_000000002.m4s     # Media segment 2
└── ...

# With ABR:
streams/
├── stream123.m3u8              # HLS master
├── stream123.mpd               # DASH master
├── stream123_360p/
│   ├── init.mp4
│   └── segment_*.m4s
├── stream123_720p/
│   ├── init.mp4
│   └── segment_*.m4s
└── stream123_1080p/
    ├── init.mp4
    └── segment_*.m4s

HLS Playlist (CMAF)

#EXTM3U
#EXT-X-VERSION:7
#EXT-X-TARGETDURATION:2
#EXT-X-SERVER-CONTROL:CAN-BLOCK-RELOAD=YES,PART-HOLD-BACK=0.6
#EXT-X-PART-INF:PART-TARGET=0.2
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-MAP:URI="stream123_init.mp4"
#EXT-X-PROGRAM-DATE-TIME:2024-01-15T10:30:00.000Z
#EXTINF:2.000,
stream123_000000000.m4s
#EXTINF:2.000,
stream123_000000001.m4s
#EXTINF:2.000,
stream123_000000002.m4s

DASH Manifest (CMAF)

<?xml version="1.0" encoding="UTF-8"?>
<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" 
     type="dynamic"
     minimumUpdatePeriod="PT2S"
     suggestedPresentationDelay="PT3S"
     availabilityStartTime="2024-01-15T10:30:00Z"
     publishTime="2024-01-15T10:30:00Z"
     timeShiftBufferDepth="PT30S">
  <Period start="PT0S">
    <!-- Video Adaptation Set -->
    <AdaptationSet mimeType="video/mp4" 
                   codecs="avc1.64001f" 
                   startWithSAP="1" 
                   segmentAlignment="true">
      <SegmentTemplate timescale="1000" 
                       media="stream123_$Number$.m4s" 
                       initialization="stream123_init.mp4" 
                       duration="2000" 
                       startNumber="0" />
      <Representation id="720p" 
                      bandwidth="2500000" 
                      width="1280" 
                      height="720" />
    </AdaptationSet>
    
    <!-- Audio Adaptation Set -->
    <AdaptationSet mimeType="audio/mp4" 
                   codecs="mp4a.40.2" 
                   startWithSAP="1">
      <SegmentTemplate timescale="1000" 
                       media="stream123_audio_$Number$.m4s" 
                       initialization="stream123_audio_init.mp4" 
                       duration="2000" 
                       startNumber="0" />
      <Representation id="audio" 
                      bandwidth="128000" 
                      audioSamplingRate="44100" />
    </AdaptationSet>
  </Period>
</MPD>

Advanced Features

HEVC/H.265 Support

CMAF has excellent HEVC support:

# Encode with HEVC
ffmpeg -i input.mp4 \
  -c:v libx265 -preset fast -b:v 2000k \
  -c:a aac -b:a 128k \
  -f dash \
  -seg_duration 2 \
  output.mpd

# Enable HEVC in Ant Media Server
settings.h265Enabled=true
settings.hlsSegmentType=fmp4

Common Encryption (CENC)

CMAF supports DRM:

# Package with Widevine and PlayReady
packager \
  'in=input.mp4,stream=video,output=video.mp4' \
  'in=input.mp4,stream=audio,output=audio.mp4' \
  --enable_widevine_encryption \
  --key_server_url "https://license.server/proxy" \
  --content_id "content123" \
  --signer "widevine_test" \
  --enable_playready_encryption \
  --mpd_output output.mpd \
  --hls_master_playlist_output output.m3u8

Troubleshooting

Playback Issues

Initialization Segment Missing:

# Check for init.mp4
ls -la /usr/local/antmedia/webapps/WebRTCAppEE/streams/*init*

# Verify init segment in playlist
curl https://your-server.com:5443/WebRTCAppEE/streams/stream123.m3u8 | grep -i init

Codec Compatibility:

# Check codec in manifest
ffprobe https://your-server.com:5443/WebRTCAppEE/streams/stream123.mpd

# Verify browser support
# In browser console:
MediaSource.isTypeSupported('video/mp4; codecs="avc1.64001f"')
MediaSource.isTypeSupported('video/mp4; codecs="hev1.1.6.L120.90"')

Segment Timing Issues:

# Validate segment durations
ffprobe -show_entries packet=pts_time,dts_time \
  https://your-server.com:5443/WebRTCAppEE/streams/stream123_000000000.m4s

Performance Optimization

# Optimize for low latency
settings.dashFragmentDuration=0.2s
settings.dashSegDuration=2s
settings.targetLatency=3s

# Optimize for quality
settings.dashFragmentDuration=2s
settings.dashSegDuration=10s
settings.useTimelineDashMuxing=true

Best Practices

Production Recommendations

Use fMP4: Set hlsSegmentType=fmp4 for CMAF benefits
Consistent GOP: Set fixed keyframe interval (e.g., 2 seconds)
Short fragments: Use 0.2-0.5s fragments for low latency
CDN optimization: Enable CORS, set appropriate cache headers
Monitor segment generation: Track timing and availability
Test across devices: Verify HLS and DASH playback

Quality Settings

settings.hlsSegmentType=fmp4
settings.dashSegDuration=1s
settings.dashFragmentDuration=0.2s
settings.lLDashEnabled=true
settings.targetLatency=2s

CMAF vs Traditional Formats

Feature	CMAF	HLS (TS)	DASH (TS)
Container	fMP4	MPEG-TS	MPEG-TS or fMP4
Storage	Single	Separate	Separate
HEVC Support	Excellent	Limited	Good
Latency	Low	Medium	Medium
Browser Support	Good	Excellent	Good
Unification	Yes	No	No

Migration Guide

From Traditional HLS to CMAF

# Before (HLS with TS)
settings.hlsSegmentType=mpegts

# After (CMAF)
settings.hlsSegmentType=fmp4
settings.dashMuxingEnabled=true

Benefits:

30-40% storage reduction
Better HEVC support
Unified HLS/DASH workflow

Resources

CMAF Specification
Apple HLS Authoring
DASH Industry Forum
Ant Media Server Enterprise Edition for LL-CMAF support

Get Started

Core Concepts

Deployment

Configuration

Streaming

Features

Security

Storage

SDKs

Operations

​Overview

​Key Benefits

​How CMAF Works

​Enabling CMAF in Ant Media Server

​Configuration

​Publishing for CMAF

​Playing CMAF Streams

​HLS with fMP4 (CMAF)

​DASH (CMAF)

​Low Latency CMAF (LL-DASH / LL-HLS)

​Configuration for Ultra-Low Latency

​LL-DASH Player Configuration

​CMAF Structure

​File Organization

​HLS Playlist (CMAF)

​DASH Manifest (CMAF)

​Advanced Features

​HEVC/H.265 Support

​Common Encryption (CENC)

​Troubleshooting

​Playback Issues

​Performance Optimization

​Best Practices

​Production Recommendations

​Quality Settings

​CMAF vs Traditional Formats

​Migration Guide

​From Traditional HLS to CMAF

​Resources

Build docs developers (and LLMs) love

Overview

Key Benefits

How CMAF Works

Enabling CMAF in Ant Media Server

Configuration

Publishing for CMAF

Playing CMAF Streams

HLS with fMP4 (CMAF)

DASH (CMAF)

Low Latency CMAF (LL-DASH / LL-HLS)

Configuration for Ultra-Low Latency

LL-DASH Player Configuration

CMAF Structure

File Organization

HLS Playlist (CMAF)

DASH Manifest (CMAF)

Advanced Features

HEVC/H.265 Support

Common Encryption (CENC)

Troubleshooting

Playback Issues

Performance Optimization

Best Practices

Production Recommendations

Quality Settings

CMAF vs Traditional Formats

Migration Guide

From Traditional HLS to CMAF

Resources