CMAF Explained: Improve Media Streaming Quality and Speed

What is CMAF?

CMAF (Common Media Application Format) is a standardized media container format designed to streamline the streaming and delivery of multimedia content across various platforms. It organizes audio and video into small, time-segmented chunks (typically 1 to 10 seconds), supporting adaptive streaming protocols like DASH (Dynamic Adaptive Streaming over HTTP) and HLS (HTTP Live Streaming).

CMAF utilizes chunked encoding to facilitate efficient bitrate adaptation, ensuring smooth playback under varying network conditions. Built on the ISO Base Media File Format (ISO BMFF), it offers codec-agnostic support for formats such as H.264 and AAC, enhancing interoperability. Additionally, CMAF incorporates common encryption methods for secure streaming and DRM integration, ultimately reducing storage costs and simplifying media workflows.

In contrast, without CMAF, streaming relies on a mix of container formats (like TS or MP4), leading to potential compatibility issues, increased complexity, and less efficient adaptive streaming.

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With CMAF:

• DASH: Utilizes CMAF for chunked encoding, enabling efficient adaptive streaming. CMAF's standardized chunks allow for reduced latency and improved compatibility across players.
• HLS: Benefits from CMAF's ability to handle small segments, enabling quick switching between different quality levels. This results in smoother playback experiences.
• Storage: Reduces redundancy in media files, leading to lower storage costs and more efficient use of bandwidth.

Without CMAF:

• DASH: Typically relies on a variety of container formats (e.g., MP4, WebM), leading to potential compatibility issues and increased complexity in streaming setups. Chunk sizes may vary, complicating adaptive streaming.
• HLS: May use legacy formats like TS (Transport Stream), which can be less efficient and increase latency due to larger segment sizes and potential for increased overhead.
• Interoperability: Without a standardized format like CMAF, media workflows become more fragmented, making it harder to ensure consistent playback quality across different devices.

Why use CMAF?

CMAF (Common Media Application Format) is a game-changer for developers looking to optimize video delivery workflows. Here’s why it’s essential from a technical perspective:

1. Low latency streaming: CMAF’s chunked transfer support allows for low-latency streaming by breaking media files into fMP4 fragments. These smaller chunks can be processed and streamed as they are received, significantly reducing end-to-end latency. This is crucial for real-time applications like live sports, online gaming, and interactive streaming, where reducing delay directly impacts user experience.
2. Single packaging for HLS and DASH: Instead of managing multiple formats for HLS and MPEG-DASH streams, CMAF allows you to serve both protocols from the same media files. This not only simplifies your packaging pipeline but also reduces storage complexity. You can generate a single fragmented MP4 file compatible with both protocols, allowing you to optimize storage, reduce processing overhead, and streamline deployment.
3. Efficient CDN utilization: By consolidating streams into a single format, CMAF helps reduce cache fragmentation on Content Delivery Networks (CDNs). With fewer variations of the same content to manage, CDNs can more efficiently store and deliver media segments, improving delivery speed and reliability at scale. This directly impacts your network efficiency and reduces delivery costs.
4. Interoperability and standardization: CMAF standardizes media formats across devices and platforms. For developers, this means less fragmentation when targeting multiple playback environments (browsers, mobile devices, smart TVs) and fewer issues with compatibility. It simplifies the integration process, reducing the need for custom handling for different formats, allowing you to focus on optimizing the experience rather than dealing with format-specific bugs

Features of CMAF

Chunked encoding: CMAF supports chunked encoding, which allows media content to be delivered in small segments or "chunks." This enables adaptive bitrate streaming, where the quality of the stream can dynamically adjust based on network conditions, providing a smoother viewing experience.

Compatibility: CMAF is designed to work with existing codecs like H.264, H.265 (HEVC), and AAC. This means you can use it with your current media files without needing to re-encode everything.

Low latency: One of the primary goals of CMAF is to reduce the delay in streaming. It enables low-latency streaming, which is essential for live broadcasts and interactive applications, such as gaming and sports.

Adaptive streaming: CMAF supports adaptive bitrate streaming, allowing users to enjoy a smooth experience regardless of their internet connection. This means the video quality can automatically adjust based on the user's bandwidth.

Segmented delivery: CMAF divides media files into smaller segments, typically around 2 to 10 seconds each. This makes it easier to deliver content efficiently and allows for faster loading times.

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Workflow of CMAF

The workflow of CMAF (Common Media Application Format) involves several key stages that streamline the process of creating, delivering, and playing multimedia content. Here’s a detailed overview of the CMAF workflow:

1. Content creation

• Source material: High-quality audio and video content is produced, often in a raw format (e.g., uncompressed video files).
• Encoding: The source material is encoded using various codecs (such as H.264 for video and AAC for audio) to prepare it for streaming.

2. Segmentation

• Chunking: The encoded media is divided into small segments, typically ranging from 1 to 10 seconds. This segmentation is crucial for efficient streaming and enables adaptive bitrate streaming.

3. Packaging

• CMAF compliance: The segmented audio and video streams are packaged into CMAF-compliant containers based on the ISO Base Media File Format (ISO BMFF). This ensures that the media can be easily recognized and processed by various players and devices.
• Inclusion of metadata: Additional metadata (such as subtitles, captions, and chapter markers) is embedded within the CMAF structure, enhancing user experience.

4. Encryption

• Common encryption (CENC): If content protection is needed, the media can be encrypted using CENC. This allows for the same media files to be compatible with multiple digital rights management (DRM) systems, protecting content while ensuring accessibility.

5. Storage and distribution

• Upload to CDN: The packaged CMAF files are uploaded to a Content Delivery Network (CDN) or media server for distribution. CDNs help ensure that content is delivered efficiently and with minimal latency to users around the world.
• File structure: CMAF files are organized in a way that allows for easy retrieval of segments, optimizing the delivery process.

6. Streaming protocols

• Integration with DASH/HLS: CMAF is compatible with adaptive streaming protocols like DASH (Dynamic Adaptive Streaming over HTTP) and HLS (HTTP Live Streaming). These protocols manage the delivery of segments to users based on current network conditions.

7. Playback

• Media player request: When a user accesses content, the media player sends requests for the initial segments of the CMAF stream.
• Adaptive quality adjustment: As playback begins, the player monitors network conditions and can adjust the quality of the stream in real-time by switching between different segments (higher or lower bitrate) as needed.
• Buffering and playback: The player buffers segments as they are downloaded, providing a smooth viewing experience with minimal interruptions.

8. User interaction

• Features: Users can interact with the media, such as selecting subtitles, adjusting playback speed, or navigating through chapters. The embedded metadata facilitates these features.

9. Analytics and feedback

• Monitoring: Content providers can monitor playback performance, user engagement, and other analytics to make informed decisions about future content and streaming strategies.‍

The CMAF workflow streamlines the entire process of multimedia content delivery, from encoding and segmentation to distribution and playback. By leveraging standardized formats and protocols, CMAF enhances compatibility, efficiency, and user experience in streaming applications.

Technical aspects of CMAF

Structure of CMAF

CMAF is built on the ISO Base Media File Format (ISOBMFF), which is the same foundation used by formats like MP4. This compatibility means that existing tools and players that support MP4 will likely work with CMAF.

Fragmented MP4 (fMP4)

CMAF uses fragmented MP4 (fMP4) files, which allow for faster access to media segments. These fragments can be delivered independently, making it easier for adaptive streaming.

Integration with DASH and HLS

CMAF works seamlessly with both Dynamic Adaptive Streaming over HTTP (DASH) and HTTP Live Streaming (HLS). This means you can implement CMAF in various streaming scenarios without worrying about compatibility.

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CMAF allows you to create a single set of video files that work with both DASH and HLS, eliminating the need for separate files and saving time and storage. This integration improves playback quality, simplifies switching between video qualities, and reduces latency. By using fMP4 instead of older formats, CMAF streamlines online delivery with a simple manifest for mapping video segments, helping platforms save space and processing power while boosting live streaming speed and lowering costs.

CMAF and DRM: Enhancing secure streaming

One of the significant advantages of CMAF (Common Media Application Format) is its seamless integration with Digital Rights Management (DRM) systems, providing developers with a robust framework for securing video content. Here’s how CMAF optimizes DRM implementation:

1. DRM compatibility across platform: CMAF is designed to work with multiple DRM systems like Apple FairPlay, Google Widevine, and Microsoft PlayReady. This is particularly useful for developers because it allows the same media stream to be encrypted once and delivered across various platforms, while still being compatible with each platform's DRM requirements. The media is packaged in fragmented MP4 (fMP4), which can be encrypted using the Common Encryption Scheme (CENC), making it interoperable across different playback environments.
2. Simplified encryption workflows: With CMAF, you can use a single encryption process that works for both HLS and DASH protocols. This eliminates the need to manage separate encryption workflows for each protocol, streamlining the DRM integration. Using CENC within CMAF, developers only need to encrypt the content once, and that encrypted content can then be used with multiple DRMs. This simplifies both your media processing pipeline and key management.
3. Content protection with common encryption (CENC): CMAF’s use of CENC ensures that a single encryption key can be used across different DRM systems. CENC supports both CBCS (Cipher Block Chaining with Subsample Encryption) and CTR (Counter Mode Encryption), offering flexibility depending on the DRM requirements. This allows developers to adopt a unified encryption scheme, reducing complexity and making it easier to protect content without duplicating efforts across different platforms.
4. Granular access control: CMAF, when combined with a DRM, allows for fine-grained control over content access. You can assign different DRM licenses for different quality levels or regions, ensuring that premium content remains protected. This is especially critical in scenarios like subscription services or pay-per-view events, where access to certain streams needs to be tightly controlled and monitored.
5. DRM performance optimization with CMAF: CMAF’s support for smaller media fragments also benefits DRM by reducing the amount of data that needs to be decrypted at a time. This can lead to more efficient decryption and smoother playback, especially for adaptive bitrate streaming (ABR), where players frequently switch between different bitrates. For developers, this translates to better performance and reduced resource load on the client side while maintaining secure content delivery.

Use cases of CMAF

CMAF (Common Media Application Format) has a variety of use cases across different industries and applications, largely due to its efficiency and compatibility. Here are some prominent use cases:

1. Live streaming

• Sports events: CMAF is ideal for delivering live sports broadcasts, where low latency and real-time adaptive streaming are crucial for viewer engagement.
• Concerts and events: Live music performances and events benefit from CMAF’s ability to handle multiple streams and provide a seamless viewing experience.

2. Video-on-demand (VOD)

• Content libraries: Streaming services (like Netflix and Hulu) can use CMAF to deliver vast libraries of on-demand content with adaptive bitrate streaming, optimizing playback based on users' bandwidth.
• Educational platforms: Online learning platforms can utilize CMAF to offer video lectures and instructional content, ensuring smooth playback and accessibility features.

3. OTT (Over-the-Top) services

• Streaming applications: CMAF is widely used in OTT services to deliver video content over the internet without traditional cable or satellite distribution, enhancing compatibility across various devices.
• Subscription-based services: Platforms like Disney+ leverage CMAF for secure streaming with DRM integration to protect their content.

4. Adaptive bitrate streaming

• Mobile streaming: Mobile applications use CMAF to provide a smooth streaming experience on varying network conditions, allowing users to switch between quality levels without interruption.
• Smart TVs and devices: CMAF ensures compatibility across a range of smart TVs and devices, allowing for high-quality streaming that adapts to the user's internet connection.

5. Content delivery networks (CDNs)

• Efficient distribution: CDNs can use CMAF to optimize the delivery of content across geographical regions, ensuring low latency and high availability for users worldwide.
• Scalable solutions: CMAF enables CDNs to manage large volumes of traffic and efficiently serve content during peak demand times.

6. Interactive media

• Gaming and esports: CMAF supports interactive video experiences, such as live-streamed gaming and esports events, where users engage with real-time content and dynamic quality adjustments are essential.
• Virtual Reality (VR) and Augmented Reality (AR): CMAF can be used to stream high-quality VR and AR content, accommodating the unique requirements of immersive experiences.

CMAF's versatility makes it suitable for a wide range of applications, from live and on-demand streaming to interactive and immersive experiences. Its ability to enhance streaming efficiency, security, and compatibility positions it as a key technology in modern media delivery.

Using FFmpeg for CMAF with MPEG-DASH support

FFmpeg is a powerful tool for handling multimedia files, and it has good support for CMAF (Common Media Application Format) and MPEG-DASH (Dynamic Adaptive Streaming over HTTP).

Setting up FFmpeg

Before you can start using FFmpeg to create CMAF for MPEG-DASH, you need to make sure you have it installed. You can download it from the official FFmpeg website or use a package manager for your operating system.

Installation on linux

sudo apt update
sudo apt install ffmpeg

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Installation on macOS

brew install ffmpeg

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Installation on windows

You can download a pre-built binary from the FFmpeg website and add it to your system PATH.

Creating CMAF segments with FFmpeg

To generate CMAF segments for MPEG-DASH, you’ll typically follow these steps:

• Transcode the video: Use FFmpeg to transcode your source video into the desired codec (H.264 or H.265 are common).
• Segment the video: Use the CMAF-compatible options to segment the video into smaller chunks.

Here’s an example command that transcodes a video and generates CMAF segments for MPEG-DASH:

ffmpeg -i input.mp4 \
    -map 0 -c:v copy -c:a copy \
    -f dash \
    -dash_segment_filename "segment_$Number$.m4s" \
    -init_seg_name "init.mp4" \
    -out "manifest.mpd" \
{-out  “manifest.m3u8”}
    -movflags +faststart \
    -profile live \
    -streaming 1 \
    -seg_duration 4 \
    -min_seg_duration 4 \
    output.mpd

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Breakdown of the command

• -i input.mp4: Specifies the input video file.
• -map 0: Maps all streams from the input.
• -c:v copy -c:a copy: Copies the video and audio codecs without re-encoding (you can change this if needed).
• -f dash: Specifies the output format as DASH.
• -dash_segment_filename "segment_$Number$.m4s": Defines the naming pattern for the segmented files.
• -init_seg_name "init.mp4": Names the initialization segment.
• -out "manifest.mpd": Specifies the name of the DASH manifest file.
• -movflags +faststart: Optimizes the MP4 files for faster web playback.
• -profile live: Sets the profile for live streaming.
• -streaming 1: Enables streaming mode.
• -seg_duration 4: Sets the duration of each segment (in seconds).
• -min_seg_duration 4: Ensures that segments are no shorter than this duration.

Testing your setup

After running the command, you should have a set of .m4s segment files and a manifest.mpd file. You can test your DASH stream using a player that supports MPEG-DASH, such as:

• Shaka Player
• Dash.js

Simply point the player to the manifest.mpd file to start streaming.

Using FFmpeg to create CMAF-compliant files for MPEG-DASH streaming is straightforward and efficient. By following the steps outlined above, you can easily prepare your media for adaptive streaming, ensuring a smooth playback experience for users across different devices and network conditions.

How to reduce the latency of CMAF?

Reducing latency in CMAF (Common Media Application Format) streaming is crucial for applications like live sports or interactive broadcasts. Here are several strategies to minimize latency:

Optimize segment duration

Shorter segments: Use shorter segment durations (e.g., 1 to 2 seconds instead of the typical 4 to 10 seconds). This allows the player to receive and play segments faster.

FFmpeg example:

ffmpeg -i input.mp4 -f dash -seg_duration 1 -min_seg_duration 1 output.mpd

Use low latency profiles

Low latency modes: Utilize low latency profiles in CMAF. The live profile is designed specifically for live streaming scenarios.

Adjust buffering settings

Reduce buffer size: In your player’s configuration, lower the buffer size to reduce the waiting time before playback starts.

Player settings: Configure the player to use minimal pre-buffering and seek buffering options.

Enable HTTP/2 or QUIC

Faster connections: Use HTTP/2 or QUIC protocols, which can improve latency through multiplexing and reduced connection overhead.

Optimize encoding settings

Fast encoding: Use faster encoding presets that maintain reasonable quality while reducing encoding time. For example, with H.264, using a faster preset like ultrafast or superfast.

FFmpeg example:

ffmpeg -i input.mp4 -c:v libx264 -preset ultrafast -f dash output.mpd

Use CMAF fragmented MP4

Fragmented MP4 (fMP4): Ensure you're using fragmented MP4, which allows for quicker access to segments. This is important for low-latency applications.

Leverage CDN and edge servers

Content delivery network (CDN): Use a CDN that offers low-latency delivery and edge caching. Positioning servers closer to users reduces round-trip times.

Monitor network conditions

Adaptive bitrate streaming: Implement adaptive bitrate streaming to adjust quality based on current network conditions, ensuring smooth playback without stalling.

Test with low latency players

Choose the right player: Use media players that are optimized for low-latency streaming, such as Shaka Player or Dash.js, and configure them for low latency.

By implementing these strategies, you can significantly reduce latency in CMAF streaming. Always test and monitor your setup to find the best combination of settings for your specific use case. Reducing latency not only enhances the user experience but also makes your streaming solution more competitive.

Conclusion

In a world where viewers expect high-quality content delivered instantly, CMAF emerges as a vital tool for developers and content providers. Its compatibility with both HLS and DASH, combined with features like low latency and adaptive streaming, makes it an ideal choice for modern media delivery. By simplifying workflows and reducing costs, CMAF not only enhances user experiences but also empowers developers to create efficient streaming solutions.

At FastPix, we understand the importance of seamless media streaming, and integrating CMAF into our platform allows us to offer users the best possible experience. Whether you're streaming live sports or the latest blockbuster, CMAF ensures that every show, game, and event is delivered flawlessly and without delay.

Embracing CMAF at FastPix means you're always equipped to meet the demands of today’s viewers while staying ahead in the competitive streaming market. Join us in leveraging the power of CMAF to transform your streaming experience.

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