Overview
ISO/IEC 14496-4:2004/Amd 7:2005 is Amendment 7 to Part 4 (Conformance testing) of the ISO/IEC 14496 suite (MPEG‑4). This amendment adds AFX conformance extensions, introducing new conformance tests, test sequences and requirements for extended Synchronization Layer (SL) features and the M4Mux tool. It clarifies bitstream and terminal conformance measurement procedures, file-signalling needs (TRIF), and the pass/fail diagnosis approach for these extensions.
Key topics and requirements
- New test sequences and features - Amendment 7 appends a table of AFX features and associated test sequences, including items such as:
- SFVec4f, CoordinateInterpolator4D, PositionInterpolator4D
- NURBS and quadric animation sequences (e.g., Nurbs_curve_anim, Quadric_anim_st)
- extendedUpdate operations (PROTO list insertion/deletion, PROTO deletion, multiple replacements, GlobalQuantizationConfiguration)
- NodeDeletionEx
- SL (Synchronization Layer) extensions conformance (subclause 4.13):
- Bitstream conformance: SL-packetized bitstreams must comply with subclause 7.3.2 of ISO/IEC 14496-1:2004. Syntax checks are strict - zero tolerance; results are pass/fail.
- Terminal conformance: Semantic tests verify SL behavior (e.g., Access Unit recovery in decoding buffers), coherence between ODProfile and SL extensions, and SLExtensionDescriptor rules (hasESID, mode, dependency pointers, marker descriptors).
- TRIF file syntax: Where MP4 cannot carry required signalling, the TRIF format (defined in ISO/IEC 14496-5:2001) is mandated for SL/M4Mux signalling.
- M4Mux tool conformance (subclause 4.13.2):
- Bitstream requirements reference subclause 7.4.2 of ISO/IEC 14496-1:2004 (strict syntax; pass/fail).
- Terminal tests cover FlexDemux behavior, M4Mux packet header structure, M4Mux Timing/Ident/Channel/CodeTable/BufferSize descriptors, and constraints on versioning, ES_ID mapping and buffer/channel usage.
- Measurement procedures include detailed header and descriptor checks; again, no tolerance - pass/fail diagnoses.
Applications and users
This amendment is directly relevant to:
- Codec and system implementers (MPEG‑4 encoder/decoder authors) verifying conformance to AFX SL extensions and M4Mux.
- Multiplexer/demultiplexer and tool vendors implementing M4Mux and TRIF signalling.
- Conformance test labs and QA teams performing interoperability and compliance testing with pass/fail criteria.
- Device manufacturers and streaming platform engineers ensuring correct handling of extended SL features and bitstream semantics.
Related standards
Keywords: ISO/IEC 14496-4, MPEG‑4 conformance testing, AFX conformance extensions, Synchronization Layer (SL), M4Mux, TRIF, bitstream conformance, terminal conformance, conformance test sequences.
Open preview (PDF)Information technology — Coding of audio-visual objects — Part 4: Conformance testing — Amendment 7: AFX conformance extensions
