Technologies de l'information - Codage des objets audiovisuels - Partie 15: transport de couche d'abstraction de réseau (NAL) unité la vidéo structuré en format de fichier multimédia de base ISO

This part of ISO/IEC 14496 specifies the storage format for AVC (ISO/IEC 14496-10) video streams.

The storage of AVC content uses the existing capabilities of the ISO base media file format but also defines extensions to support the following features of the AVC codec.

- Switching pictures:
 

• to enable switching between different coded streams and substitution of pictures within the same stream.

- Sub-sequences and layers:
 

• provides a structuring of the dependencies of a group of pictures to provide for a flexible stream structure (e.g. in terms of temporal scalability and layering).

- Parameter sets:
 

• the sequence and picture parameter set mechanism decouples the transmission of infrequently changing information from the transmission of coded macroblock data. Each slice containing the coded macroblock data references the picture parameter set containing its decoding parameters. In turn, the picture parameter set references a sequence parameter set that contains sequence level decoding parameter information.

The file format for storage of SVC content, as defined in Annexes A to E, and the file format for storage of MVC content, as defined in Annexes B to F, use the existing capabilities of the ISO base media file format and the plain AVC file format (i.e. the file format specified in Clauses 2 to 5 not including SVC and MVC supports specified in Annexes A to F). In addition, the following new extensions, among others, to support SVC- and/or MVC-specific features are specified.

- Scalable or multiview grouping:
 

• a structuring and grouping mechanism to indicate the association of NAL units with different types and hierarchy levels of scalability.

- Aggregator:
 

• a structure to enable efficient scalable grouping of NAL units by changing irregular patterns of NAL units into regular patterns of aggregated data units.

- Extractor:
 

• a structure to enable efficient extraction of NAL units from other tracks than the one containing the media data.

- Temporal metadata statements:
 

• structures for storing time-aligned information of media samples.

- AVC compatibility:
 

• a provision for storing an SVC or MVC bitstream in an AVC compatible manner, such that the AVC compatible base layer can be used by any plain AVC file format compliant reader.