R-REC-BT.1120-4-200305-S!!PDF-E[1]

Rec. ITU-R BT.1120-4 1 RECOMMENDATION ITU-R BT.1120-4 Digital interfaces for HDTV studio signals (Question ITU-R 42/6) (1994-1998-2000-2003) The ITU Radiocommunication Assembly, considering a) that in the scope of Recommendation ITU-R BT.709, studio standards for HDTV have been developed for 1125- and 1250- line systems, which comprise systems related to conventional television as well as systems with the square pixel common image format (CIF) including progressive scanning; b) that Recommendation ITU-R BT.709 contains the following HDTV studio standards to cover a wide range of applications: for systems related to conventional television: – 1125 total line, 2:1 interlace scanning, 60 fields/s, 1035 active line standard; – 1250 total line, 2:1 interlace scanning, 50 fields/s, 1152 active line standard. for systems with CIF (1920 × 1080): – 1125 total lines and 1080 active lines; – picture rates of 60, 50, 30, 25 and 24 Hz, including progressive, interlace and segmented frame transport; c) that in Recommendation ITU-R BT.709, the 1920 × 1080 HD-CIF is given as a preferred format for new installations, where interoperability with other applications is important, and work is being directed with the aim of reaching a unique worldwide standard; d) that the HD-CIF systems provide a common data rate feature, which allows for the use of a unique digital interface; e) that a whole range of equipment based on the above systems has been developed or is being developed and is commercially available now or soon, including all that necessary for broadcasting chains and for industrial applications; f) that many programmes are being produced in the above systems using the above equipments and that in the development of broadcasting and other services there is an increasing need for HDTV production installations; g) that the use of digital technology and digital interconnection is highly desirable to reach and maintain the level of performance required for HDTV; h) that there are clear advantages for establishing interface specifications for HDTV production installations, recommends 1 that the specifications described in this Recommendation should be used for the basic digital coding as well for the bit-parallel and bit-serial interfaces for HDTV studio signals. 2 Rec. ITU-R BT.1120-4 PART 1 Interfaces for HDTV signals conforming to Recommendation ITU-R BT.709, Part 1 1 Digital representation 1.1 Coding characteristics The signals to be digitized should comply with the characteristics described in Recommendation ITU-R BT.709, Part 1. 1.2 Construction of digital signals See Part 2, § 1.2. TABLE 1 Digital coding parameters Value Item Parameter 1125/60/2:1 1250/50/2:1 1 Coded signals Y, CB, CR ou R, G, B These signals are obtained from gamma pre-corrected signals, namely BGRCRCBY EEEEEE ′′′′′′ ,,or,, Also see Recommendation ITU-R BT.709, Part 1 2 Sampling lattice – R, G, B, Y Orthogonal, line and picture repetitive 3 Sampling lattice – CB, CR Orthogonal, line and picture repetitive, co-sited with each other and with alternate Y samples. The first active colour-difference samples are co- sited with the first active Y sample 4 Number of active lines 1035 1152 5 Sampling frequency (1) – R, G, B, Y (MHz) 74.25 72 6 Sampling frequency (1) – CB, CR Half of luminance sampling frequency 7 Number of samples/line – R, G, B, Y – CB, CR 2200 1100 2304 1152 8 Number of active samples/line – R, G, B, Y – CB, CR 1920 960 9 Position of the first active Y, CB, CR sampling instants with respect to the analogue sync timing reference OH (2) (see Fig. 6) 192 T 256 T 10 Coding format Uniformly quantized PCM for each of the video component signals 8 or 10 bit/sample 10 bit preferable Rec. ITU-R BT.1120-4 3 TABLE 1 (end ) 2 Digital interface The interface provides a unidirectional interconnection between a single source and a single destination. The data signals are in the form of binary information and are coded accordingly: – video data (8-bit or 10-bit words); – timing reference and identification codes (8-bit or 10-bit words except for 1250/50/2:1, which use 10-bit words only); – ancillary data (see Recommendation ITU-R BT.1364). 2.1 Video data Y, CB, CR signals are handled as 20-bit words by time-multiplexing CB and CR components. Each 20-bit word corresponds to a colour-difference sample and a luminance sample. The multiplex is organized as: (CB1 Y1) (CR1 Y2) (CB3 Y3) (CR3 Y4) ... where Yi indicates the i-th active sample of a line, while CBi and CRi indicate the colour-difference samples of CB and CR components co-sited with the Yi sample. Note that the index “i” on colour-difference samples takes only odd values due to the half-rate sampling of the colour-difference signals. The data words corresponding to digital levels 0.00 through 0.75 and 255.00 through 255.75 are reserved for data identification purposes and must not appear as video data. For 1125/60/2:1, R, G, B signals are handled as 30-bit words in addition to the above 20-bit words for Y, CB, CR signals. Value Item Parameter 1125/60/2:1 1250/50/2:1 11 Quantization level assignment (3) – Video data – Timing reference 1.00 through 254.75 0.00 and 255.75 (4) 12 Quantization levels (5) – Black level R, G, B, Y – Achromatic level CB, CR – Nominal peak – R, G, B, Y CB, CR 16.00 128.00 235.00 16.00 and 240.00 13 Filter characteristics See Recommendation ITU-R BT.709 (1) The sampling clock must be locked to the line frequency. The tolerance on frequency is ±0.001% for 1125/60/2:1 and ±0.0001% for 1250/50/2:1, respectively. (2) T denotes the duration of the luminance sampling clock or the reciprocal of the luminance sampling frequency. (3) To reduce confusion when using 8-bit and 10-bit systems together, the two LSBs of the 10-bit system are read as two fractional bits. The quantization scale in an 8-bit system ranges from 0 to 255 in steps of 1, and in a 10-bit system from 0.00 to 255.75 in steps of 0.25. When 8-bit words are presented in a 10-bit system, two LSBs of zeros are to be appended to the 8-bit words. (4) In the case of a 8-bit system, eight MSBs are used. (5) These levels refer to precise nominal video levels. Signal processing may occasionally cause the signal level to deviate outside these ranges. 4 Rec. ITU-R BT.1120-4 2.2 Video timing relationship with analogue waveform The digital line occupies m clock periods. It begins at f clock periods prior to the reference transition (OH) of the analogue synchronizing signal in the corresponding line. The digital active line begins at g clock periods after the reference transition (OH). The values for m, f and g are listed in Table 2. See Fig. 6 and Table 2 for detailed timing relationships in the line interval. The start of digital field is fixed by the position specified for the start of the digital line. See Fig. 1 and Table 3 for detailed relationships in the field interval. TABLE 2 Line interval timing specifications 2.3 Video timing reference codes (SAV and EAV) There are two timing reference codes, one at the beginning of each video data block (start of active video, SAV) and the other at the end of each video data block (end of active video, EAV). These codes are contiguous with the video data, and continue during the field/frame blanking interval, as shown in Fig. 1. Value Symbol Parameter 1125/60/2:1 1250/50/2:1 Interlace ratio 2:1 Number of active Y samples per line 1920 Luminance sampling frequency (MHz) 74,25 72 a Analogue line blanking (µs) 3.771 6.00 b Analogue active line (µs) 25.859 26.00 c Analogue full line (µs) 29.630 32.00 d Duration between end of analogue active video and start of EAV (T) 0-6 24 e Duration between end of SAV and start of analogue active video (T) 0-6 24 f Duration between start of EAV and analogue timing reference OH (T) 88 128 g Duration between analogue timing reference OH and end of SAV (T) 192 256 h Video data block (T) 1928 i Duration of EAV (T) 4 j Duration of SAV (T) 4 k Digital line blanking (T) 280 384 l Digital active line (T) 1920 m Digital line (T) 2200 2304 NOTE 1 – The parameter values for analogue specifications expressed by the symbols a, b and c indicate the nominal values. NOTE 2 – T denotes the duration of the luminance sampling clock or the reciprocal of the luminance sampling frequency. Rec. ITU-R BT.1120-4 5 Each code consists of a four-word sequence. The bit assignment of the word is given in Table 14. The first three words are the fixed preamble and the fourth word carries the information that defines field identification (F), field/frame blanking period (V), and line blanking period (H). In an 8-bit implementation bits Nos. 9 to 2 inclusive are used; note in 1250/50/2:1 all 10 bits are required. The bits F and V change state synchronously with EAV at the beginning of the digital line. The value of protection bits, P0 to P3, depends on the F, V and H as shown in Table 15. The arrangement permits one-bit errors to be corrected and two-bit errors to be detected at the receiver, but only in the 8 MSBs, as shown in Table 16. 1120-01 0 2 2 0 2 2 6 6 4 4 6 6 L1 L2 L3 L4 L5 L6 L7 L8 L9 L10 L11 L127 7 5 5 7 7 3 3 1 1 3 3 Digital line blanking EAV SAV 1 fr am e Fi el d N o. 1 Fi el d N o. 2 Field No. 1 active video Field No. 2 active video Value of (F/V/H) Value of (F/V/H) 1 digital line Note 1 – The values of (F/V/H) for EAV and SAV represent the status of bits for F, V, and H; in a way that the three-bit word composed of F, V, H represents a binary number expressed in decimal notation (F corresponding to MSB and H to LSB). For example, the value 3 represents the bits of F = 0, V = 1 and H = 1. FIGURE 1 Field timing relationship 6 Rec. ITU-R BT.1120-4 TABLE 3 Field interval timing specifications 2.4 Ancillary data See Part 2, § 2.4. 2.5 Data words during blanking See Part 2, § 2.5. 3 Bit-parallel interface For the system of 1125/60/2:1, the bits of the digital code words which describe the video signal are transmitted in parallel by means of 20 or 30 shielded conductor pairs. The 20 conductor pairs are used for the transmission of the signal set consisting of luminance Y and time-multiplexed colour-difference CB/CR components. The 30 conductor pairs are used for the transmission of R, G, B signals or Y, CB/CR components with an additional data stream (auxiliary channel). An additional shielded conductor pair carries the synchronous clock at 74.25 MHz. Digital line number Symbol Definition 1125/60/2:1 1250/50/2:1 Number of active lines 1035 1152 L1 First line of field No. 1 1 L2 Last line of digital field blanking No. 1 40 44 L3 First line of field No. 1 active video 41 45 L4 Last line of field No. 1 active video 557 620 L5 First line of digital field blanking No. 2 558 621 L6 Last line of field No. 1 563 625 L7 First line of field No. 2 564 626 L8 Last line of digital field blanking No. 2 602 669 L9 First line of field No. 2 active video 603 670 L10 Last line of field No. 2 active video 1120 1245 L11 First line of digital field blanking No. 1 1121 1246 L12 Last line of field No. 2 1125 1250 NOTE 1 – Digital field blanking No. 1 denotes the field blanking period that is prior to the active video of field No. 1, and digital field blanking No. 2 denotes that prior to the active video of field No. 2. Rec. ITU-R BT.1120-4 7 For the 1250/50/2:1 system, the bits of digital code words that describe the video signal are transmitted in parallel by means of 20 signal pairs, where each pair carries a stream of bits, 10 pairs for luminance data and 10 pairs for time-multiplexed colour-difference data. The 20 pairs can also carry ancillary data. A 21st pair provides a synchronous clock at 36 MHz. Data signals are transmitted in non-return-to-zero (NRZ) form in real time (unbuffered). 3.1 Clock signal and clock-to-data timing relationship For the system of 1125/60/2:1, the transmitted clock signal is a square wave, of which positive transitions occur midway between the data transitions as shown in Fig. 8 and Table 4. For 1250/50/2:1, the transmitted clock signal is a 36 MHz square wave of unity mark/space ratio, the transitions of which are coincident with the transition of the data (see Fig. 2). A logical high state of the clock is concurrent with Y and CB data samples and a logical low state with Y and CR data samples, as shown in Fig. 2 and Table 4. TABLE 4 Clock signal specifications Value Parameter 1125/60/2:1 1250/50/2:1 Sampling frequency for Y, R, G, B signals (MHz) 74.25 72 Clock period Tck Nominal value (ns) 1/(2200 fH) 13.468 1/(1152 fH) 27.778 Clock pulse width, t 0.5 Tck Tolerance ±0.11 Tck (nominal) Clock jitter Within ±0.04 Tck Within ±0.5 ns from the average time of transition over one field in interlace systems, and over one frame in progressive systems Data timing, Td Tolerance 0.5 Tck ±0.075 Tck 0.25 Tck (nominal) NOTE 1 – fH denotes the line frequency. NOTE 2 – Values are specified at the sending end (source). 8 Rec. ITU-R BT.1120-4 1120-02 t Y1 CB1 Y2 CR1 CB3Y3 FIGURE 2 Clock to data timing relationship for 1250/50/2:1 Clock Data Nominal data detection points Tck TdTd 3.2 Electrical characteristics of the interface The interface employs 21 line drivers and line receivers, in the case of the transmission of Y and CB/CR components. Each line driver has a balanced output and the corresponding line receiver has a balanced input. For 1125/60/2:1, the interface employs 31 line drivers and line receivers, in the case of R, G and B components or Y, CB/CR with an additional data stream (auxiliary channel). Although the use of ECL technology is not mandatory, the line driver and receiver must be ECL 10 k compatible for 1125/60/2:1, and ECL 100 k compatible for 1250/50/2:1, i.e. they must permit the use of ECL for either drivers or receivers. The receiver must sense correctly the data when a random signal produces conditions represented by the eye diagram of Fig. 3. Rec. ITU-R BT.1120-4 9 TABLE 5 Line driver characteristics TABLE 6 Line driver characteristics Value Item Parameter 1125/60/2:1 1250/50/2:1 1 Output impedance (Ω) 110 maximum 100 maximum 2 Common mode voltage (1) (V) –1.29 ± 15% –1.3 ± 15% 3 Signal amplitude(2) (V) 0.6 to 2.0 p-p 0.8 to 2.0 p-p 4 Rise and fall times (3) ≤ 0.15 Tck < 3 ns 5 Difference between rise and fall times ≤ 0.075 Tck ≤ 1.0 ns NOTE 1 – Tck denotes the clock period (see Table 4). (1) Measured relative to ground. (2) Measured across a resistive load having the nominal impedance of the assumed cables, that is 110 Ω for 1125/60/2:1, and 100 Ω for 1250/50/2:1. (3) Measured between the 20% and 80% points across a resistive load having the nominal impedance of the assumed cable. Value Item Parameter 1125/60/2:1 1250/50/2:1 1 Input impedance (Ω) 110 ± 10% 100 ± 10% 2 Maximum input signal voltage (V) 2.0 p-p 3 Minimum input signal voltage (mV) 185 p-p 4 Maximum common mode voltage (1) (V) ±0.3 ±0.5 5 Differential delay Tmin (2) 0.3 Tck 4.5 ns NOTE 1 – Tck denotes the clock period (see Table 4). (1) Comprising interference in the range DC to line frequency (fH). (2) Data must be correctly sensed when the differential delay between the received clock and data is within this range (see Fig. 3). 10 Rec. ITU-R BT.1120-4 1120-03 FIGURE 3 Idealized eye diagram corresponding to the minimum input signal level Reference transition of clock Note 1 – For 1125/60/2:1, the width of the window in the eye diagram, within which data must be correctly detected, comprises ±0.04 T clock jitter, ±0.075 T data timing, and ±0.18 T propagation skew of conductor pairs. For 1250/50/2:1, the aggregate of clock jitter, data timing and propagation skew of conductor pairs must not exceed 4.5 ns. Tmin Tmin Vmin 3.3 Mechanical characteristics 3.3.1 Connector The interface uses a multi-contact connector. Connectors are locked by two screws on the cable connectors and two threaded bolts on the equipment. Cable connectors employ pin contacts and equipment connectors employ socket contacts. Shielding of the connectors and cables is mandatory. For 1125/60/2:1, a 93-contact connector is used. Contact assignments are indicated in Tables 20 and 21. The mechanical specifications for the connectors are shown in Figs. 11, 12 and 13. For 1250/50/2:1, a 50-contact type D subminiature connector is used. Contact assignments are indicated in Table 7 and Fig. 4 (for information, suggested contact assignment for a printed circuit board (PCB) header are shown in Fig. 5). 3.3.2 Interconnecting cable For 1125/60/2:1, two types of multichannel cable, either 21 or 31 channels, can be used in accordance with the transmission signal set (see Table 21). The cable consists of twisted pairs with an individual shield for each pair. It also contains an overall shield. The nominal characteristic impedance of each twisted pair is 110 Ω. The cable shall possess the characteristics that satisfy the conditions of the eye diagram shown in Fig. 3 up to a maximum cable length of 20 m. Rec. ITU-R BT.1120-4 11 For 1250/50/2:1, a cable with 21-channel balanced conductor pairs is used. The nominal characteristic impedance of each conductor pair is 100 Ω. Cable length up to 30 m may be employed when a high-quality cable is used. TABLE 7 Connector contact assignment for 1250/50/2:1 1120-04 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 FIGURE 4 Mating face of connector receptacle containing male pins (plug) for 1250/50/2:1 Note 1 – The preferred orientation for connectors, mounted vertically or horizontally, is with contact 1 uppermost. Contact Signal line Contact Signal line Contact Signal line 1 Clock A (CKA) 34 Clock B 2 GND 18 GND 35 GND 3 Data 9A (D9A) 19 GND 36 Data 9B 4 Data 8B 20 Data 8A 37 Data 7A 5 Data 6A 21 Data 7B 38 Data 6B 6 Data 5B 22 Data 5A 39 Data 4A 7 Data 3A 23 Data 4B 40 Data 3B 8 Data 2B 24 Data 2A 41 Data 1A 9 Data 0A 25 Data 1B 42 Data 0B 10 GND 26 GND 43 GND 11 Data 19A 27 GND 44 Data 19B 12 Data 18B 28 Data 18A 45 Data 17A 13 Data 16A 29 Data 17B 46 Data 16B 14 Data 15B 30 Data 15A 47 Data 14A 15 Data 13A 31 Data 14B 48 Data 13B 16 Data 12B 32 Data 12A 49 Data 11A 17 Data 10A 33 Data 11B 50 Data 10B NOTE 1 – Data 9-Data 0 represent each bit of the luminance signal (Y ), and Data 19-Data 10 that of time-multiplexed colour-difference signal (CR /CB ). The suffix 19 to 0 indicates the bit number (bit 19 denotes MSB for CR/CB and bit 9 MSB for Y ). A and B correspond to the terminals A and B of Fig. 9, respectively. 12 Rec. ITU-R BT.1120-4 1120-05 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 5034 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 D10BD9B D7A D6B D4A D3B D1A D0B D19B D17A D16B D14A D13B D11A 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 D8A D7B D5A D4B D2A D1B D18A D17B D15A D14B D12A D11B D9A D8B D6A D5B D3A D2B D0A D19A D18B D16A D15B D12B D10AD13A 1 5 10 15 20 25 30 35 40 45 50 D 9A D 8A D 7A D 6A D 5A D 4A D 3A D 2A D 1A D 0A D 19A D 18A D 17A D 16A D 15A D 14A D 13A D 12A D 11A D 10A D 9B D 8B D 7B D 6B D 5B D 4B D 3B D 2B D 1B D 0B D 19B D 18B D 17B D 16B