IEC 62447-3:2007 pdf download – Helical-scan compressed digital video cassette system using 6,35 mm magnetic tape – Format D-12 – Part 3: Data stream format
4 Identification within the serial data transport interface (SDTI)
4.1 SDTI header packet data The header packet data words of the serial data transport interface (SDTI) associated with this data stream format shall conform to SMPTE 305M. When the SDTI interface transports a data stream conforming to this standard, the block type word within the SDTI header packet shall have the value 1 73 h for transported data contained in fixed-size blocks when ECC is used and the value 233 h when ECC is not used.
4.2 Payload The payload is composed of consecutive fixed-size blocks (see Figure 1 ). The SDTI data type word shall identify the data type of this payload with the value 221 h .
5 Stream block format
5.1 Stream block The stream block format is shown in Figure 1 . The length of each stream block is 1 70 words, including a secondary header, two DIF (digital interface) block IDs, two DIF block data (of stream data) and an ECC block. The secondary header contains reserved data words, signal type words, and a transmission type word. The complete word structure of the stream block for a compressed video data stream is defined below.
5.2 Reserved data words The reserved data words shall consist of 3 words and be positioned at the start of the stream block. The default value for the reserved data is 200 h .
5.3 Signal type words The signal type word (ST) mapping is shown in Figure 2. The signal type words shall consist of two words. The first word of ST (word 3) includes the specific type of video frame ID (STVF ID). The second word of ST (word 4) includes the field/frame frequency flag (FF), the DIF structure format, the DIF valid flag (DVF), the frame sequence number flag (FSNF), the transmission rate flag (TRF) and reserved bits.
a) Word 3 of ST
The STVF ID shows information mainly related to pictures that have been 3:2 pull-down converted from 480 line/29,98 frame rate progressive pictures.
All values of bits B7 through B0 are set to 00 h as default values.
Bit B8 of word 3 is equal to the even parity of B7 through B0.
Bit B9 of word 3 is equal to the complement of B8.
b) Word 4 of ST
Bit B7 indicates the field frequency of SDI with the following values:
Bit B3 is reserved bit and shall be set to 0 b as default value.
Bit B2 is the DVF and indicates the validity of the DIF data mapped into SDTI.
5.6 DIF block data words
The DIF block data shall consist of 77 words. The lower 8 bits of each DIF block word represent the DIF block data, as specified in SMPTE 370M; the higher 2 bits are parity data.
Bits B7 through B0 are DIF block data; Bit B8 is equal to the even parity of B7 through B0;
Bit B9 is equal to the complement of B8.
5.7 ECC words
Bits B7 through B0 of the words within a stream block (including reserved data words, the ST word, the TT word and all words of the DIF block ID and DIF block data) are optionally protected by an ECC. The ECC shall consist of four words and be inserted at the end of the stream block.
The ECC is a (1 70,1 66) Reed-Solomon code in GF(256), whose field generator polynomial is shown as:
P(x) = X 8 + X 4 + X 3 + X 2 + 1
where X i are place-keeping variables in GF(2), the binary field.
The generator polynomial of the code in GF(256) is:
G(x) = (x+α)(x+α 2 )(x+α 3 )(x+α 4 )
where α is given by 2 h in GF(256).
When the value of the block type in the SDTI header (see 4.1 ) is 1 73 h , the Reed-Solomon code shall be contained in C31 through C0 as shown in Figure 5. When the value of the block type is 233 h , the ECC shall have the fixed value 200 h .IEC 62447-3 pdf download.
