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IEC 62328-1-2005: Multimedia Home Server Systems Architecture
Key Insight: IEC 62328-1 defines the volume and file structure for interchanging multimedia data between home servers and broadcasting receivers, enabling seamless recording, playback, and content exchange across different devices and broadcasting systems.
1. Scope and Architectural Overview
IEC 62328-1 specifies the volume and file structure required for interchanging multimedia data of a home server or broadcasting receiver. The standard addresses the fundamental challenge of enabling AV streams with multiple associated objects to be recorded, stored, and played back on interchangeable storage media such as optical disks and hard drives. It provides a framework that allows content recorded on one device to be understood and played on another, regardless of the manufacturer.
The architecture is built around the concept of a programme reference (PGR) — a pointer that references all or part of the AV stream in a programme. Programme references can be organized hierarchically into programme reference groups (PGRGs), enabling flexible content navigation and editing capabilities.
Design Engineering Insight: The hierarchical PGRG structure allows for sophisticated content management features such as bookmarking, ad-skipping, and playlist creation without modifying the underlying AV stream data. This separation of metadata from media data was a forward-looking design choice that remains relevant in modern streaming and DVR systems.
2. Content Architecture
2.1 Basic Content Architecture Elements
The content architecture defined in IEC 62328-1 consists of several fundamental building blocks that work together to manage recorded broadcast content:
| Element | Symbol | Function | Description |
|---|---|---|---|
| Programme Reference | PGR | Navigation | Points to a segment or entire AV stream within a programme |
| Programme Reference Group | PGRG | Hierarchy | Set of PGRs or nested PGRGs for structured content |
| Access Unit Table | AUT | Indexing | Maps time positions to byte offsets in the AV stream |
| Allocation Unit Table | ALU | Storage | Describes how data blocks are allocated on storage media |
| Time Unit Table | TUT | Temporal | Provides time-based access to stream positions |
| Index Table | IDX | Search | Enables fast searching and trick-play modes |
2.2 AV Stream and Data Management
The standard defines how MPEG transport streams (TS) from digital broadcasting are recorded and managed. A key concept is the partial TS — a transport stream derived from the original broadcast by modifying PSI/SI information and optionally removing unnecessary elementary streams. This allows efficient storage while preserving the essential content and timing information needed for playback.
The content architecture supports multiple associated objects linked to the main AV stream, including thumbnail images, programme guide information, and conditional access system (CAS) data for content protection.
Engineering Consideration: The partial TS approach requires careful handling of PCR (Programme Clock Reference) timestamps. Removing or modifying elementary streams can disrupt the timing model if the PCR-bearing packets are not properly managed. Implementations must ensure that the partial TS maintains valid timing references for all retained streams.
3. Security and Conditional Access
IEC 62328-1 addresses the critical issue of content protection through its security module framework. The standard supports integration with various conditional access systems (CAS), including those specific to different broadcasting regions (DVB in Europe, ATSC in North America, ISDB in Japan). The security architecture ensures that:
- Encrypted AV streams can be stored without decryption, maintaining end-to-end security
- License information is stored alongside the content, enabling authorized playback
- Copy control information (CCI) is preserved throughout the recording and playback chain
- Cipher block chaining (CBC) encryption modes are supported for content protection
| Broadcasting System | CAS Type | Region | Compatibility with IEC 62328 |
|---|---|---|---|
| DVB | DVB-CSA (Common Scrambling Algorithm) | Europe | Full support |
| ATSC | DCAS (Downloadable CAS) | North America | Full support |
| ISDB | Multi-2 / B-CAS | Japan | Full support (Part 3 specific) |
| DTMB | China DRM / SAS | China | Adaptable framework |
4. Recording Model and Decoding
The standard defines two fundamental recording models: digital TV recording and analogue TV recording. For digital TV, the incoming MPEG transport stream is partially processed to extract the desired programme, which is then stored as a TVRS partial TS. For analogue TV, the video and audio signals are encoded into MPEG format before storage, following the same file structure.
The decoding model specifies how recorded content is retrieved from storage, descrambled (if encrypted), and presented for playback. The architecture supports seamless playback across storage media boundaries and enables advanced features such as simultaneous recording and playback (trick-play).
5. Engineering Design Insights
Key considerations for implementing systems compliant with IEC 62328-1 include:
- File system compatibility: The standard is designed to work with standard file systems compliant with ISO/IEC 13346 (UDF), enabling interchange across multiple operating systems and device platforms
- Stream synchronization: When broadcast data contains multiple associated objects (e.g., video, audio, subtitles), the volume structure must ensure temporal synchronization across storage and retrieval
- Metadata resilience: Programme references and index tables should be protected against corruption, as they are essential for content navigation
- Forward compatibility: The architecture supports future broadcasting enhancements through extensible PGRG structures and table definitions
FAQ 1: What is the relationship between IEC 62328 and IEC 62330?
Both standards address digital video recording but in different domains. IEC 62328 covers multimedia home server systems and broadcasting receivers with interchangeable storage media. IEC 62330 specifically covers professional HD-D5 digital video cassette recording systems using 12.65 mm magnetic tape.
FAQ 2: How does IEC 62328 handle high-definition content?
The standard is content-format agnostic — it works with any MPEG transport stream, including HDTV broadcasts. The file structure accommodates the higher data rates of HD content, and the access unit table supports the frame-level indexing needed for HD trick-play modes.
FAQ 3: Can IEC 62328 be used with IP-based streaming services?
While the standard was originally designed for broadcast-based recording scenarios, its file structure and programme reference concepts are adaptable to IP-delivered content. However, the primary focus remains on MPEG transport streams from traditional broadcasting.
FAQ 4: What is the significance of the TVRS format in this standard?
TVRS (TV Recording Format Specific) is the partial TS recording format defined in IEC 62328. It specifies how the broadcast transport stream is transformed into a stored recording while preserving all necessary timing, programme, and service information for faithful playback.
