What is DRM and how it works in Live Video Streaming

What is DRM?

Digital Rights Management (DRM) is a set of tools used to protect digital media and software from unauthorized use, copying, or sharing. In simple terms, it’s a way for creators, companies, and publishers to control how their content is accessed and used, making sure only the right people can interact with it.

Key concepts in DRM

To understand how DRM functions, it’s essential to focus on its three main components: encryption, access control, and usage restrictions.

Let’s explore these concepts in more detail:

1. Encryption
Encryption is the foundation of DRM. It acts like a security lock, scrambling the content so that only those with the correct decryption key can access it. 
For example, when you try to copy a DVD or Blu-ray movie, it’s not easy because the content is encrypted specifically to prevent such actions. 

2. Access Control
Access control decides who can use the content and under what conditions. Usually, DRM systems require users to verify their identity before accessing digital media. This might mean logging in with an account or getting permission through a third-party service. Services like Netflix or Spotify use access control, where only subscribers can view or listen to content after signing in.

3. Usage Restrictions
Once someone has access to the content, usage restrictions define what they can and can’t do with it. For instance, you might be able to stream a movie but not download it. Or you could read an e-book but can’t share it with a friend. These restrictions are there to protect the creator’s rights and prevent unauthorized sharing.

How these components work together

DRM is a combination of encryption, access control, and usage restrictions. Together, they create a secure system for managing digital content:

• Encryption keeps the content secure.
• Access control makes sure only authorized users can access it.
• Usage restrictions limit what users can do with the content.

In short, DRM helps maintain control over digital media, ensuring it’s used in ways that respect the creator’s rights while still allowing access for authorized users.

Common DRM capabilities

• Restricting actions: DRM can prevent users from editing, copying, saving, sharing, printing, or taking screenshots of content, ensuring tighter control over how the material is used.
• Setting expiry dates: DRM can limit access to content by setting expiration dates, after which users can no longer access it. It can also limit the number of times content can be accessed or viewed.
• Device and location restrictions: DRM can restrict access to content based on specific devices, IP addresses, or geographic locations. For example, content may only be available to users in a certain country or region.
• Watermarking: DRM can apply watermarks to documents, images, or videos to assert ownership and track unauthorized use, providing an additional layer of protection.

How does DRM work in video streaming?

In streaming video, platforms use adaptive, segmented streaming protocols like HLS or MPEG DASH. These protocols deliver video in small segments (2 to 10 seconds long) at various quality levels based on your internet speed. This ensures smooth playback even if your connection fluctuates.

Here’s how the DRM process works for video streaminng:

Step 1: Starting with the Source File

It all begins with a video file that needs to be prepared for streaming. 

To make sure viewers can enjoy the best quality no matter their internet speed, the video gets transcoded into multiple versions, or ABR renditions (Adaptive Bitrate). This means the video is broken into several quality levels, from low to high, that can switch automatically based on your connection.

Step 2: Encrypting the Video

As the video is prepared for streaming, it’s also encrypted for security. The process ensures that no one can just get the video and use it without permission. The ABR renditions are transformed into packages for HLS (for Apple devices) and DASH (a common format for adaptive streaming), and encryption is applied.

Step 3: Creating Manifests and Encryption Types

The video is now encrypted, but it also needs a “roadmap” or manifest for the player to follow. There are a few different versions of this:

• DASH Manifest: Comes with special metadata for Google Widevine and Microsoft PlayReady, which are popular DRM systems.
• CENC Encrypted Video: This encryption is used for DASH streaming.
• SAMPLE-AES Encrypted Video: This type of encryption is used for HLS streams.
• HLS Manifest: Includes metadata for Apple’s FairPlay DRM.

Step 4: Distributing the Video via CDN

Once everything’s encrypted and ready, the video is sent to a CDN (Content Delivery Network). The CDN’s job is to store the video and deliver it quickly and smoothly to viewers, no matter where they are in the world.

Step 5: Player Makes a Request

When a viewer presses play, their video player first asks the CDN for the appropriate manifest — the roadmap that guides the player on how to download the right video chunks for smooth playback based on their network speed.

But before the player can actually show the video, it needs permission to unlock it. The player sends a request to the DRM license server. 

Step 6: Receiving the Decryption Key

If everything checks out (the viewer is authorized to watch the content), the license server sends back a license, which includes the decryption key needed to unlock and play the video.

Step 8: Playing the Video

With the decryption key in hand, the player unlocks the video, decrypts the content, and starts playing it for the viewer.

A critical part of this process is the Content Decryption Module (CDM). The CDM is responsible for decrypting the video and managing the license exchange. It also enforces restrictions, like preventing screenshots or screen recordings of protected content.

How to Implement DRM

Implementing DRM in video streaming involves three key components:

1. Content: Your videos must be transcoded, encrypted, and packaged in formats that work with the DRM systems you're using.

2. Player: The video player needs to request a decryption key from a license server and decrypt the video. You may need different players for different platforms.

3. License Server: The player requests decryption keys from the license server, which verifies the user and grants access to the content.

Common DRM Technologies

Below are three widely-used DRM solutions: Apple FairPlay, Google Widevine, and Microsoft PlayReady.

1. Apple FairPlay

Apple FairPlay is Apple’s DRM technology designed to secure its digital content, including music, movies, and TV shows. It uses encryption and access control to ensure only authorized users can access content. Integrated seamlessly into Apple’s ecosystem, it provides an optimal experience for users on Apple devices.

• Platforms Supported: Apple devices
• Key Features: Encryption, access control, fully integrated into the Apple ecosystem

2. Google Widevine

Google Widevine is a widely adopted DRM solution used by major content providers such as Netflix, Hulu, and Amazon Prime Video. It supports multiple platforms, including Android, iOS, and Chrome browsers. Widevine offers varying security levels, from software-based encryption to secure hardware execution environments.

• Platforms Supported: Android, iOS, Chrome browsers
• Key Features: Multiple security levels, software and hardware-based encryption

3. Microsoft PlayReady

Microsoft PlayReady is a robust DRM technology used to protect digital content across Windows devices, Xbox, and other platforms. It supports various media formats such as MPEG-DASH, HLS, and CMAF, offering strong security features like encryption and access control. PlayReady is commonly used in the media and entertainment industry to protect premium content.

• Platforms Supported: Windows, Xbox, other platforms
• Key Features: Supports multiple formats, encryption, access control

Since different devices and platforms rely on different DRM systems, content distributors typically implement support for all three to ensure compatibility and accessibility for a broad audience. Without support for these DRM systems, users on certain devices may be unable to access the content.

Challenges and Debates

While DRM does a good job of protecting content, it often comes with some drawbacks for users.

Limited Ownership: One of the biggest complaints about DRM is that it can make users feel like they don’t truly own the digital content they’ve purchased. You might buy a movie or an e-book, but DRM can restrict what you can do with it — like transferring it to other devices or making a personal backup.

Compatibility Issues: Not all devices support every type of DRM, which can lead to headaches. For example, content that works perfectly on one platform might be totally inaccessible on another. This can be frustrating for users who want flexibility in how they access their media.

Privacy Concerns: Some DRM systems require you to authenticate or provide personal information before accessing content. For those who are cautious about sharing their data, this can feel invasive and raise privacy concerns.

Fair Use Limitations: DRM can also limit users’ ability to exercise fair use rights. This includes making personal backups, sharing content for educational purposes, or using parts of it in creative works like reviews or commentaries.

In short, while DRM is essential for protecting digital content and ensuring creators’ rights, it needs to strike a balance between security and user experience. To be truly effective and fair, DRM implementation should consider how users interact with the content they’ve purchased.