NAL Fragmentation for Scalable Broadcast Streaming
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Solution Overview
Problem
Current adaptive streaming technologies, such as DASH, are inadequate for simultaneous content delivery to multiple clients, leading to delays and inefficiencies in real-time reproduction, especially in scenarios like sports relays, due to their point-to-point HTTP streaming nature and lack of scalability.
Innovation Solution
A communication apparatus and method that divides encoded data into NAL unit fragments, generates packets with additional position information, and transmits them in HTTP packets, allowing for broadcast or multicast delivery, enabling efficient reconstruction and decoding by clients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If point-to-point HTTP streaming (DASH) is used for content delivery, then adaptive bit rate selection and client-specific optimization are improved, but scalability for simultaneous multi-client delivery and real-time reproduction deteriorates
Solution Approach 1:
The patent segments the encoded data into NAL unit fragments (smaller units than traditional GOPs) and transmits them in separate packets. This fine-grained segmentation enables broadcast/multicast delivery while maintaining adaptability, as each fragment can be independently processed and reassembled by clients based on their bit rate requirements.
Solution Approach 2:
The patent introduces an additional dimension of fragmentation within the NAL unit level, creating a hierarchical structure where NAL units are divided into fragments that can be transmitted independently. This dimensional change from traditional GOP-level segmentation to NAL fragment-level segmentation enables simultaneous broadcast delivery while preserving client-specific adaptation capabilities.
2Ease of manufacture
If traditional GOP-based segmentation is used, then encoding simplicity is maintained, but packet size control for MTU compliance and transmission efficiency deteriorates
Solution Approach 1:
The patent applies segmentation at the NAL unit level, dividing each NAL unit into smaller fragments that can fit within MTU constraints. This maintains encoding simplicity (no complex re-encoding is needed) while significantly improving transmission efficiency through better packet size control and reduced fragmentation overhead.
Solution Approach 2:
The patent changes the segmentation parameter from traditional GOP-based approaches to NAL unit-based fragmentation. This parameter change allows for flexible control of packet sizes to match MTU requirements while maintaining the simplicity of the encoding process, as the fragmentation occurs at the packetization stage rather than during encoding.
3Device complexity
If NAL unit fragments are transmitted without position information, then packet structure simplicity is maintained, but data reconstruction accuracy and playback continuity deteriorate
Solution Approach 1:
The patent extracts position information (NAL unit start position and end position) as separate metadata fields within the packet header. This allows the packet structure to remain relatively simple while adding the necessary information for accurate reconstruction. The extracted position data enables receivers to correctly reassemble fragments without complex processing.
Solution Approach 2:
The patent introduces position information as an intermediary element between the fragmented NAL units and the reconstruction process. This intermediary metadata layer provides the necessary context for accurate reassembly without requiring complex changes to the core packet structure or encoding/decoding algorithms.
Data Source
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AI summary
A configuration in which encoded data is divided into data equal to or less than a maximum data transfer unit (MTU) specified on a communication path and transmitted, and a reception apparatus restores and reproduces the data is provided. A transmission apparatus generates a plurality of packets storing divisional data generated by dividing encoded data serving as a transmission target into data equal to or less than a maximum data transfer unit (MTU) specified on a communication path and additional information serving as arrangement information of the divisional data and sequentially transmits the packets. For example, NAL unit fragments obtained by further dividing a NAL unit are stored in each packet, and the packets are transmitted. The reception apparatus arranges NAL unit fragments stored in the packets in a divided manner with reference to the additional information of the packets and reconstructs and decodes the NAL unit.