Overview
IEC 62447-3:2007 specifies the data stream format for the D‑12 helical‑scan compressed digital video cassette system (6.35 mm tape). It defines how DV‑based audio, data and compressed video (data structures per SMPTE 370M) are carried synchronously over the Serial Data Transport Interface (SDTI) defined in SMPTE 305M. The standard covers transmission for DV‑based 100 Mb/s structures used in 525/60 (59.94 Hz) and 625/50 SDTI systems and supports transport over 270 Mb/s and 360 Mb/s SDI rates.
Key topics and requirements
- SDTI identification and payload: SDTI header packet values are defined for D‑12 streams (SDTI data type = 0xDD; block type = 0xAD when ECC used, 0xE9 when not).
- Stream block format: Fixed‑size stream blocks of 170 words, including a secondary header (3 reserved words, 2 signal type words, 1 transmission type word), two DIF block IDs and data payloads (3 + 77 words each), and a 4‑word ECC block.
- Signal Type (ST) words: Two words carry the STVF (video frame ID), field/frame frequency flag (FF), DIF structure identifier (25/50/100 Mb/s structures), DIF valid flag (DVF), frame sequence number flag (FSNF) and transmission rate flag (TRF), with parity bits.
- Transmission Type (TT) word: Encodes frame sequence number and transmission rate multiplier (normal rate = 1× up to 16×), plus parity bits.
- DIF block ID mapping: Three words map DIF block identifiers (A0–A23) with parity bits (EP1–EP3) and follow lower‑byte definitions in SMPTE 370M.
- Error correction (ECC): ECC word structure and use are specified for reliable transport when ECC is present.
- Mapping and transmission order: Rules for channel unit mapping and transmission ordering across frames and DIF sequences are defined (including mappings for 100 Mb/s structures and higher SDI rates).
Applications and users
IEC 62447-3 is practical for:
- VTR and recorder manufacturers designing D‑12 helical‑scan recorders and tape‑based systems.
- Broadcast engineers and system integrators implementing SDTI/SDI transport of DV‑based compressed video and audio.
- Archive and post‑production facilities handling tape ingest/export where D‑12 format interoperability is required.
- Firmware, middleware and software developers implementing packetization, mapping, ECC handling and SDTI header generation for D‑12 streams.
Related standards
- SMPTE 305M - Serial Data Transport Interface (referenced normative interface).
- SMPTE 370M - DV‑based compressed video data structure (payload definitions).
- IEC 62447‑1 / IEC 62447‑2 - D‑12 VTR system specifications (Part 1) and encoding/data format for HD systems (Part 2).
Keywords: IEC 62447-3, D-12, data stream format, SDTI, DV-based compressed video, helical-scan, DIF, ECC, SMPTE 305M, SMPTE 370M, 525/60 SDTI, 625/50 SDTI.