Secure Fast Channel Change in Live OTT Streaming
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Solution Overview
Problem
Existing live content streaming solutions face challenges in providing secure and fast channel change due to delays in acquiring DRM licenses, which affect the time-to-first-video and channel change speed, especially in live over-the-top (OTT) media services, as they often require serial decryption and rendering processes that are hindered by the availability of decryption keys.
Innovation Solution
The solution involves encrypting media content using both service-level and channel-level access keys, allowing clients to join any channel on a segment protected with the service-level key without waiting for the channel license, and acquiring the channel license in parallel with content acquisition, ensuring secure and fast channel changes by decoupling license acquisition from channel change processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DRM license acquisition is performed serially before content playback, then content security is maintained, but channel change speed and time-to-first-video are degraded
Solution Approach 1:
The system performs preliminary DRM license acquisition for the service level before content playback begins. The service-level license is obtained in advance and cached, enabling immediate decryption of service-protected segments without waiting for channel-specific licenses during channel changes
Solution Approach 2:
The encryption scheme is segmented into two independent layers: service-level encryption and channel-level encryption. This segmentation allows the client to acquire and cache the service-level license independently, while channel-level licenses are acquired only when needed for specific channel changes, reducing overall waiting time
2Speed
If channel license is acquired in parallel with content acquisition, then channel change speed is improved, but license management complexity increases
Solution Approach 1:
The license management system is segmented into service-level license management and channel-level license management. The service-level license is managed once per service session and cached, while channel-level licenses are managed independently per channel change event, simplifying the overall management complexity despite parallel operations
Solution Approach 2:
The service-level license is acquired preliminarily before any channel changes occur. This preliminary action establishes a foundation that remains valid across channel changes, allowing parallel acquisition of channel-level licenses without compounding complexity
3Reliability
If dual-layer encryption (service-level and channel-level) is implemented, then security is enhanced, but decryption processing overhead increases
Solution Approach 1:
The encryption is segmented into service-level and channel-level layers with different security requirements. Service-protected segments use only service-level encryption with a cached license, reducing decryption overhead. Channel-protected segments use both layers but only when channel change security is required
Solution Approach 2:
Different security levels are applied locally to different segments based on their protection requirements. Service-protected segments have lower decryption overhead using only the service-level license, while channel-protected segments have higher overhead but are used selectively for enhanced security scenarios
Data Source
AI summary
Techniques for secure fast channel change in live content streaming are described. In some embodiments, during content preparation, a packager and/or an encoder encrypts media content items at both the service level (e.g., by encrypting a first portion of the plurality of segments with a service level access key unique to a service) and the channel level (e.g., by encrypting a second portion of the plurality of segments with a channel level access key unique to a channel associated with the service). On the receiving end, a client device (e.g., a media player) requests a service level access key prior to content acquisition. As such, a client can join any channel on a segment protected with the service level key without waiting for a license for that channel first, and the channel license can be acquired in parallel with the content acquisition during channel switching.