DIVO is a video option for Onyx2 graphics, Origin200, and Origin2000 deskside and server workstations. Supporting the SMPTE 259 10-bit digital video standard, it fully integrates video into Silicon Graphics workstation and server environments.
The option utilizes one XIO slot and provides dual-link 10-bit serial digital component input and output ports. Depending on the system type, multiple DIVO boards can be installed on a system for video server applications.
This chapter discusses
DIVO features include
dual-link 10-bit serial digital video (SMPTE 259) streaming to and from system memory
AES3-1992 (AES/EBU) embedded audio and ancillary data (SMPTE 272M) with up to 24-bit precision and sample rates of 32 KHz, 44.1 KHZ, and 48 KHz; up to 16 channels output and 16 channels input
lossless built-in compression and decompression using adaptive entropy coding to approximately 2:1 compression
transparent color-space conversion between YUV and RGB
flexible data-packing capability to facilitate easy integration to OpenGL® component packing methods
UST/MSC (Unadjusted System Time/Media Stream Count) hardware-supported audio/video synchronization mechanisms
low latency in video transfers to/from system memory (typically less then one frame)
support for fields and frames
active video or data mode capture and playback
VITC (Vertical Internal Time Clock) extraction and insertion
hardware error detection and handling (EDH) and link autophasing
support for SDDI/CSDI interfaces
GPI-based input and output triggering mechanisms
output genlocking
DIVO supports video and audio data transfers to and from system memory only. You can view the video in real time on the Onyx2 workstation using the OpenGL interface to copy video images to graphics. A wide variety of packing formats is supported to facilitate easy integration of video in graphics.
To capture graphics to video, you can use OpenGL to read pixels into memory and send them out to the DIVO board, or you can use the GVO graphics option to get zero latency transcoding to CCIR 601 digital video. For controlling videotape recorders, you can use a direct RS-422 connection to the deck with third-party software, or an RS-422 V-LAN™ controller option and V-LAN software from Silicon Graphics with the on-board GPI triggering mechanism.
DIVO is fully integrated into the Silicon Graphics Digital Media Library interfaces. The Video Library (VL) API has been enhanced to support some of the advanced features of DIVO.
Figure 1-1 shows the top-level diagram of DIVO board. Each DIVO board has two pipes, each with its own dedicated R4650 processor and SDRAM.
Figure 1-2 shows features of the DIVO I/O panel. Although the board is installed vertically in the chassis, Figure 1-2 shows the panel sideways to aid in reading the connector and LED labels.
dTable 1-1 summarizes DIVO board external connectors that interface with video equipment.
Table 1-1. Interface for Video Equipment
Connector | Format | Use |
|---|---|---|
10-bit CCIR 601 Terminated, unbalanced
| Serial digital video input from digital tape deck or other recording device. Conforms to SMPTE 259M for component video, SMPTE 272M for embedded audio, and SMPTE 266M for DVITC. Both inputs autophased. | |
OUT LINK A, OUT LINK B | 10-bit CCIR 601 | Serial digital video output to digital tape deck or other recording device. Conforms to SMPTE 259M for component video, SMPTE 272M for embedded audio, and SMPTE 266M for DVITC. Note: The transfer mode (packing format) selected determines LINK A and LINK B usage, as explained in Table A-3 and Table A-4 in Appendix A, “DIVO I/O Panel Connector Specifications.” |
75-ohm BNC | External analog sync source (precision time base or other source of house sync) or analog loopthrough. | |
75-ohm BNC | External reference loop out; passive loopthrough for genlock input with buffered signal to workstation. Note: If you attach a cable to one GEN connector, you must attach either another cable to other equipment accepting analog sync or a 75-ohm BNC terminator to the other GEN connector. | |
8-pin mini-DIN | General Purpose Interface for each video port; frame-accurate event triggering to or from source or destination (tape deck or digital recorder). configurable for switch closure (factory setting) or current sense operation. |
See Appendix A, “DIVO I/O Panel Connector Specifications,” for technical details of the connectors, including GPI pinouts.
Table 1-2 summarizes the function of the LEDs on the panel.
LED | Purpose |
|---|---|
Leftmost LEDs between IN LINK A and IN LINK B (525 and 625) | Top LED lights when valid 525-line serial digital signal detected on IN LINK A.Bottom LED lights when valid 625-line serial digital signal detected on IN LINK A. |
Rightmost LEDs between IN LINK A and IN LINK B (525 and 625) | Valid 525-line (top LED) or 625-line (bottom LED) serial digital signal detected on |
Leftmost LEDs between OUT LINK A and OUT LINK B (525 and 625) | Valid 525-line (top LED) or 625-line (bottom LED) serial digital signal detected on OUTLINK A and OUT LINK B; these outputs are locked together, regardless of whether OUT LINK B is used. |
A-LCK | Output is locked to an analog source. Specific choices (standalone, genlock, or free run) are set with the VL_SYNC and VL_SYNC_SOURCE controls; see Table 2-2 in Chapter 2, “Programming DIVO.” |
D-LCK | Output is locked to a digital source. Specific choices (IN LINK A or IN LINK B) are set with the VL_SYNC and VL_SYNC_SOURCE controls; see Table 2-2 in Chapter 2. |
SYNC 525 and 625 | Valid 525-line sync source (top LED) or 625-line sync source (bottom LED) detected. |
Figure 1-3 diagrams how the DIVO board interacts with other workstation components.
The DIVO board has two 10-bit serial digital video ports for equipment that complies with the CCIR 601 standard. The ports can be configured for 4:4:4:4 or 4:2:2:4 in dual-link mode, or 4:2:2 in single-link mode where alpha is ignored.
Each port consists of two unidirectional interconnections, Link A and Link B:
The video format selected determines Link A and Link B usage. For more information, see the following standards, which contain provisions for video signals:
CCIR 601-2: Encoding Parameters of Digital Television for Studios (4:2:2 component video signals, single link)
ANSI/SMPTE 125M-1992: Television—Component Video Signal 4:2:2—Bit-Parallel Digital Interface
SMPTE Recommended Practice (RP) 175-1993: Digital Interface for 4:4:4:4 Component Video Signals (Dual Link)
SMPTE 259M-1993: Television—10-Bit 4:2:2 Component and 4fsc NTSC composite Digital Signals—Serial Digital Interface
SMPTE RP 157-1990: Key Signals
SMPTE 272M: Television - Formatting AES/EBU Audio and Auxiliary Data into Digital Video Ancillary Data Space
Four color spaces are native to DIVO: full-range RGBa, compressed range RGB (RP-175), CCIR601, and full-range YUV. The video interface supports only RP-175 and CCIR 601. The memory interface supports all four color spaces.
DIVO uses the Gennum® GF9105 component digital transcoder. The GF9105 uses 13-bit multiplier coefficients and provides up to 13-bit output resolution, allowing for transparent color-space conversion between YUV and RGB.
The GF9105 transcoder also provides interpolation and decimation filtering between the 4:2:2:4 and 4:4:4:4 sampling rates. Both interpolation and decimation operations are fully compliant with the CCIR 601 standard.
DIVO provides one 16-channel wide input device and one 16-channel wide output device. Applications can open either device as 2, 4, 8, or 16 channels. Unused output channels are set to zero; unused input channels are discarded.
Each device has only one master clock source, the current video clock. This clock can be set by the VL or video panel (vcp), not by the Audio Library; audio is always slaved to the video.
DIVO audio supports sample rates of 32 KHz, 44.1 KHz, and 48 KHz. It supports 20- and 24-bit word sizes (set with the AL_WORDSIZE parameter); the setting determines whether SMPTE 272M extended audio packets are to be used.