The following table describes the terms used in this application note.
| Name | Description |
|---|---|
| 12G-SDI | Common name for SMPTE ST 2082-1, the 12 Gbps serial digital interface. |
| 3G-SDI | Common name for SMPTE ST 424, the 3 Gbps serial digital interface. 3G-SDI supports three mapping modes defined in ST 425-1 called 3G-SDI level A, level B-DL, and level B-DS. Refer to ST 425-1 for details about these mapping modes. |
| 6G-SDI | Common name for SMPTE ST 2081-1, the 6 Gbps serial digital interface. |
| Ancillary (ANC) data | Non-video data embedded in portions of the SDI data stream not used for active picture data. One very common type of ANC data is embedded audio. ANC data must be formatted into ancillary data packets, as specified by SMPTE ST 291-1. |
| Data stream | The actual data into and out of the SDI interface. The data stream must be formatted according to the transport data structure as it enters and exits the SDI interface. |
| EDH | The error detection and handling protocol for SD-SDI as defined by SMPTE RP 165. |
| End of active video (EAV) | In SDI compatible data streams, the EAV is a sequence of four words, unique in the data steam, marking the end of the active portion of the line and start of the horizontal blanking interval. Each video line is considered to begin with the first word of the EAV. |
| HD-SDI | Common name for the SMPTE ST 292-1 1.5 Gbps serial digital interface. |
| Interlaced | A video scanning system in which the video frame is divided into two sequential fields. Field one consists of the odd lines and field two consist of the even lines that are displayed between the odd lines of field one. The two fields represent different pictures displaced in time by one half of the frame time. |
| Link | If the picture’s bandwidth exceeds the capacity of the serial digital interface, two or more serial digital interfaces can be ganged together to increase the bandwidth to transport the picture. Each separate serial digital interface of a multilink set is called a link. SMPTE ST 372 defines how to transport some higher bandwidth video formats on two HD-SDI links. Multilink 3G-SDI standards in the ST 425-x family are currently under development by SMPTE. The 3G-SDI level B-DL transport carries both link of a dual-link HD-SDI (ST 372) pair on one 3G-SDI interface. Each of the two HD-SDI signals carried by 3G-SDI level B-DL is still called a link. |
| Payload ID | Sometimes called the Video Payload ID (VPID), the payload ID is an ancillary data packet defined by SMPTE ST 352. The four data words of the ST 352 payload ID packet identify both the nature of the video picture (video format, frame rate, scanning structure, color space, etc) and the type of SDI interface used to transport that payload. In multilink interfaces, the payload ID also contains bits that distinguish between the individual links. |
| Progressive | A non-interlaced video scanning system. All lines of the progressive frame belong to the same picture. |
| Serial Digital Interface (SDI) | Originally referred to SMPTE ST 259, the standard-definition serial digital interface. With the advent of HD-SDI and 3G-SDI, ST 259 is now often called SD-SDI to avoid confusion. This document uses the term SDI to generically refer to SD-SDI, HD-SDI and 3G-SDI. When referring specifically to ST 259, this document always uses the term SD-SDI. |
| SD-SDI | Common name for SMTPE ST 259, the standard-definition serial digital interface. |
| SMPTE | Society of Motion Picture and Television Engineers |
| Start of active video (SAV) | In SDI compatible data streams, the SAV is a sequence of four words, unique in the data stream, marking the end of the horizontal blanking interval and the start of the active video portion of the line. The first active video sample of a line, usually called sample 0, occurs immediately after the SAV. |
| Synchronous switching (point, interval, line) | SMPTE RP 168 defines the point(s) in a video frame where it is permissible to switch between synchronous video sources. This is often called the synchronous switching point, but is actually defined as an interval – a portion of a line, rather than an exact point on a line. The line that contains the synchronous switching interval is sometimes called the synchronous switching line. |
| Transport | The data structure of an interface data stream or streams. The transport data structure defines the EAV and SAV sequences used to carry video timing information. |
| Timing reference signal (TRS) | A generic term referring to both EAV and SAV sequences. |
| XYZ | The fourth word of each EAV and SAV is called the XYZ word. This word carries the horizontal (H), vertical (V), and field (F) bits that indicate the video timing. The XYZ word also contains some protection bits that allow detection of errors in the XYZ word. |