Pengertian Serial Digital Interface
Serial digital interface uses BNC connectors Serial digital interface ( SDI ) is a family of digital video interfaces first standardized by SMPTE (The Society of.
Serial digital interface uses Serial digital interface ( SDI) is a family of interfaces first standardized by (The Society of Motion Picture and Television Engineers) in 1989. For example, and define digital used for -grade video. A related standard, known as high-definition serial digital interface (HD-SDI), is standardized in; this provides a nominal data rate of 1.485 Gbit/s.
Additional SDI standards have been introduced to support increasing video resolutions (HD, UHD and beyond), stereoscopic (3D) video, and color depth. Dual link HD-SDI consists of a pair of SMPTE 292M links, standardized by in 1998; this provides a nominal 2.970 Gbit/s interface used in applications (such as or HDTV 1080P) that require greater fidelity and resolution than standard HDTV can provide.
3G-SDI (standardized in ) consists of a single 2.970 Gbit/s serial link that allows replacing dual link HD-SDI. 6G-SDI and 12G-SDI standards were published on March 19, 2015. These standards are used for transmission of signals (optionally including embedded audio and time code) within television facilities; they can also be used for packetized data.
Serial Digital Interface (sdi)
Coaxial variants of the specification range in length but are typically less than 300 meters (980 ft). Fiber optic variants of the specification such as 297M allow for long-distance transmission limited only by maximum fiber length or repeaters. SDI and HD-SDI are usually available only in professional video equipment because various agreements restrict the use of unencrypted digital interfaces, such as SDI, prohibiting their use in consumer equipment. Several professional video and HD-video capable cameras and all uncompressed video capable consumer cameras use the interface, often called.
There are various for existing and other devices, which allow a user to add a serial digital interface to these devices. Contents.
Electrical interface The various serial digital interface standards all use (one or more) cables with, with a nominal impedance of 75. This is the same type of cable used in analog video setups, which potentially makes for easier upgrades (though higher quality cables may be necessary for long runs at the higher bitrates). The specified signal amplitude at the source is 800 (±10%) peak-to-peak; far lower voltages may be measured at the receiver owing to. Using at the receiver, it is possible to send 270 Mbit/s SDI over 300 meters (980 ft) without use of repeaters, but shorter lengths are preferred. The HD bitrates have a shorter maximum run length, typically 100 meters (330 ft).
When interface converted to fiber interface and transmit by single fibers, the maximum distance can reach to 80 kilometers (50 mi). Uncompressed digital signals are transmitted. Data is encoded in format, and a is used to the data to reduce the likelihood that long strings of zeroes or ones will be present on the interface. The interface is self-synchronizing and self-clocking. Framing is done by detection of a special pattern, which appears on the (unscrambled) serial digital signal to be a sequence of ten ones followed by twenty zeroes (twenty ones followed by forty zeroes in HD); this bit pattern is not legal anywhere else within the data payload. Main article: Like, SMPTE 292M supports the standard for ancillary data. Ancillary data is provided as a standardized transport for non-video payload within a serial digital signal; it is used for things such as embedded, timecode, and other sorts of.
Ancillary data is indicated by a 3-word packet consisting of 0, 3FF, 3FF (the opposite of the synchronization packet header), followed by a two-word identification code, a data count word (indicating 0 - 255 words of payload), the actual payload, and a one-word checksum. Other than in their use in the header, the codes prohibited to video payload are also prohibited to ancillary data payload. Specific applications of ancillary data include embedded audio, EDH, VPID and SDTI.
In dual link applications; ancillary data is mostly found on the primary link; the secondary link is to be used for ancillary data only if there is no room on the primary link. One exception to this rule is the VPID packet; both links must have a valid VPID packet present. Embedded audio Both the HD and SD serial interfaces provide for 16 channels of embedded audio. The two interfaces use different audio encapsulation methods — SD uses the SMPTE 272M standard, whereas HD uses the SMPTE 299M standard. In either case, an SDI signal may contain up to sixteen audio channels (8 pairs) embedded 48 kHz, 24-bit audio channels along with the video.
Typically, 48 kHz, 24-bit (20-bit in SD, but extendable to 24 bit) audio is stored, in a manner directly compatible with the digital audio interface. These are placed in the (horizontal) blanking periods, when the SDI signal carries nothing useful, since the receiver generates its own blanking signals from the TRS. In dual-link applications, 32 channels of audio are available, as each link may carry 16 channels. SMPTE ST 299-2:2010 extends the 3G SDI interface to be able to transmit 32 audio channels (16 pairs) on a single link. EDH As the standard definition interface carries no checksum, CRC, or other data integrity check, an EDH packet may be optionally placed in the vertical interval of the video signal. This packet includes CRC values for both the active picture, and the entire field (excluding those lines at which switching may occur, and which should contain no useful data); equipment can compute their own CRC and compare it with the received CRC in order to detect errors.
EDH is typically only used with the standard definition interface; the presence of CRC words in the HD interface make EDH packets unnecessary. VPID VPID (or ) packets are increasingly used to describe the video format. In early versions of the serial digital interface, it was always possible to uniquely determine the video format by counting the number of lines and samples between H and V transitions in the TRS. With the introduction of dual link interfaces, and standards, this is no longer possible; thus the VPID standard (defined by SMPTE 352M) provides a way to uniquely and unambiguously identify the format of the video payload.
Video payload and blanking The active portion of the video signal is defined to be those samples which follow an SAV packet, and precede the next EAV packet; where the corresponding EAV and SAV packets have the V bit set to zero. It is in the active portion that the actual image information is stored. Color encoding Several color encodings are possible in the serial digital interface. The default (and most common case) is 10-bit linearly sampled video data encoded as 4:2:2. (YCbCr is a digital representation of the colorspace).
Samples of video are stored as described above. Data words correspond to signal levels of the respective video components, as follows:. The luma (Y) channel is defined such that a signal level of 0 mV is assigned the codeword 64 (40 hex), and 700 millivolts (full scale) is assigned the codeword 940 (3AC hex). For the chroma channels, 0 mV is assigned the code word 512 (200 hex), -350 mV is assigned a code word of 64 (40 hex), and +350 mV is assigned a code word of 960 (3C0 hex).
Note that the scaling of the luma and chroma channels is not identical. The minimum and maximum of these ranges represent the preferred signal limits, though the video payload may venture outside these ranges (providing that the reserved code words of 0 - 3 and 1020 - 1023 are never used for video payload). In addition, the corresponding analog signal may have excursions further outside of this range.
Colorimetry As YPbPr (and YCbCr) are both derived from the colorspace, a means of converting is required. There are three typically used with digital video:.
High Definition Serial Digital Interface
SD and ED applications typically use a colorimetry matrix specified in. Most HD, dual link, and 3 Gbit/s applications use a different matrix, specified in.
The 1035-line HD standards specified by SMPTE 260M (primarily used in and now largely considered obsolete), used a colorimetry matrix specified by SMPTE 240M. This colorimetry is nowadays rarely used, as the 1035-line formats have been superseded by 1080-line formats. Other color encodings The dual-link and 3 Gbit/s interfaces additionally support other color encodings besides 4:2:2 YCbCr, namely:. 4:2:2 and 4:4:4 YCbCr, with an optional alpha (used for linear keying, a.k.a. ) or data (used for non-video payload) channel. 4:4:4 RGB, also with an optional alpha or data channel.
4:2:2 YCbCr, 4:4:4 YCbCr, and 4:4:4 RGB, with 12 bits of color information per sample, rather than 10. Note that the interface itself is still 10 bit; the additional 2 bits per channel are multiplexed into an additional 10-bit channel on the second link. If an RGB encoding is used, the three primaries are all encoded in the same fashion as the Y channel; a value of 64 (40 hex) corresponds to 0 mV, and 940 (3AC hex) corresponds to 700 mV. 12-bit applications are scaled in a similar fashion to their 10-bit counterparts; the additional two bits are considered to be. Vertical and horizontal blanking regions For portions of the vertical and horizontal blanking regions which are not used for ancillary data, it is recommended that the luma samples be assigned the code word 64 (40 hex), and the chroma samples be assigned 512 (200 hex); both of which correspond to 0 mV. It is permissible to encode analog vertical interval information (such as or vertical interval test signals) without breaking the interface, but such usage is nonstandard (and ancillary data is the preferred means for transmitting metadata).
Conversion of analog sync and burst signals into digital, however, is not recommended—and neither is necessary in the digital interface. Different picture formats have different requirements for digital blanking, for example all so called 1080 line HD formats have 1080 active lines, but 1125 total lines, with the remainder being vertical blanking. Supported video formats The various versions of the serial digital interface support numerous video formats.
The 270 Mbit/s interface supports 525-line, interlaced video at a 59.94 Hz field rate (29.97 Hz frame rate), and 625-line, 50 Hz interlaced video. These formats are highly compatible with and -B/G/D/K/I systems respectively; and the terms NTSC and PAL are often (incorrectly) used to refer to these formats. (PAL is a composite color encoding scheme, and the term does not define the line-standard, though it is most usually encountered with 625i) while the serial digital interface— other than the obsolete 143 Mbit/s and 177 Mbit/s forms- is a component standard. The 360 Mbit/s interface supports 525i and 625i widescreen. It can also be used to support 525p, if 4:2:0 sampling is used.
The various 540 Mbit/s interfaces support 525p and 625p formats. The nominal 1.5 Gbit/s interfaces support most formats. Supported formats include 1080/60i, 1080/59.94i, 1080/50i, 1080/30p, 1080/29.97p, 1080/25p, 1080/24p, 1080/23.98p, 720/60p, 720/59.94p, and 720/50p. In addition, there are several 1035i formats (an obsolete Japanese television standard), half-bandwidth 720p standards such as 720/24p (used in some film conversion applications, and unusual because it has an odd number of samples per line ), and various 1080psf (progressive, segmented frame) formats. Progressive Segmented frames formats appear as but contain video which is progressively scanned. This is done to support analog monitors and televisions, many of which are incapable of locking to low field rates such as 30 Hz and 24 Hz. The dual link HD interface supports 1080/60p, 1080/59.94p, and 1080/50p, as well as 4:4:4 encoding, greater color depth, RGB encoding, alpha channels, and nonstandard resolutions (often encountered in computer graphics or ).
A quad link interface of HD-SDI supports UHDTV-1 resolution 2160/60p Related interfaces In addition to the regular serial digital interface described here, there are several other similar interfaces which are similar to, or are contained within, a serial digital interface. Main article: There is an expanded specification called ( Serial Data Transport Interface), which allows compressed (i.e., and others) video streams to be transported over an SDI line. This allows for multiple video streams in one cable or faster-than-realtime (2x, 4x.) video transmission.
A related standard, known as HD-SDTI, provides similar capability over an SMPTE 292M interface. The SDTI interface is specified by SMPTE 305M. The HD-SDTI interface is specified by SMPTE 348M. SMPTE 349M The standard SMPTE 349M: Transport of Alternate Source Image Formats through SMPTE 292M, specifies a means to encapsulate non-standard and lower-bitrate video formats within an HD-SDI interface. This standard allows, for example, several independent standard definition video signals to be multiplexed onto an HD-SDI interface, and transmitted down one wire.
This standard doesn't merely adjust EAV and SAV timing to meet the requirements of the lower-bitrate formats; instead, it provides a means by which an entire SDI format (including synchronization words, ancillary data, and video payload) can be encapsulated and transmitted as ordinary data payload within a 292M stream. High-Definition Multimedia Interface (HDMI). ^ Charles A. Poynton (2003).
Morgan Kaufmann. ^ John Hudson (2013). Francis Rumsey, John Watkinson. Retrieved 2016-01-14. Retrieved 2016-01-14. European Broadcasting Un. Retrieved 20 July 2015.
Retrieved 20 July 2015. February 2018.
(PDF). Retrieved 19 September 2014. SMPTE (2013). Standards. Society of Motion Picture and Television Engineers: SMPTE 274M-2005: Image Sample Structure, Digital Representation and Digital Timing Reference Sequences for Multiple Picture Rates. Society of Motion Picture and Television Engineers: SMPTE 292M-1998: Bit-Serial Digital Interface for High Definition Television.
Society of Motion Picture and Television Engineers: SMPTE 291M-1998: Ancillary Data Packet and Space Formatting. Society of Motion Picture and Television Engineers: SMPTE 372M-2002: Dual Link 292M Interface for 1920 x 1080 Picture Raster External links.
Comments are closed.