Active Frame	An AutoCirculate term, the frame buffer in an AJA device’s SDRAM that is currently being recorded from the incoming video signal during capture, or that’s being sent to the output jack during playout.
Anc	A contraction for Ancillary Data, which is non-video metadata that’s embedded in the video signal.
Bypass	Shunting the signal received by a device’s input connector directly to its output connector.
CEA-608	The old U.S. standard for encoding captions as a waveform on line 21 of a standard-definition television signal.
CEA-708	The new U.S. standard for encoding captions inside data packets in the ancillary data areas of HD digital television signals.
DMA	Direct Memory Access, an efficient method for transferring data between a peripheral device and host memory without directly involving the host CPU(s).
DRAM	Dynamic Random Access Memory, a type of random access memory that must be periodically refreshed, or else it will “forget” what it was storing.
Driver	Low-level software that operates at the operating system “kernel” level to control a peripheral device.
E-E	“End-to-End” … a routing from an input jack to an output jack without going through an intermediate Frame Store to buffer frames.
Field	The odd or even horizontal lines that comprise a single frame of interlaced video.
FIFO	Acronym for “First-In, First-Out” — in this context represents a hardware data pipeline that outputs data in the same order as pushed into its input. The length of the FIFO determines the latency through it.
FPS	Acronym for “Frames Per Second”, used to measure frame rate.
Frame	A complete video image.
Frame Buffer	A contiguous chunk of RAM used to store a frame of video pixel data, either on the host computer or in an AJA device.
Frame Store	A device widget having mode, pixel format and video format properties (e.g., Capture, 10-bit YCbCr, and 1080i50), that, when enabled, can write/read video frame data to/from device SDRAM. Often used interchangeably with the word “Channel”.
HANC	Horizontal Ancillary Data, is ancillary data that is embedded into the video lines that are between the start and end of active video.
HD	High Definition television standards: NTV2_STANDARD_720, NTV2_STANDARD_1080, NTV2_STANDARD_1080p or more.
HDMI	High-Definition Multimedia Interface, a compact hardware interface used for transferring video and audio data between compatible devices.
HEVC	High Efficiency Video Coding, H.265/HEVC is a video compression standard, a successor to H.264/MPEG-4 AVC (Advanced Video Coding).
HFR	High Frame Rate … usually 60 fps minimum.
Host	The computer that is connected to the AJA device.
IDE	Integrated Development Environment, a software application that provides comprehensive facilities to programmers for performing interactive software development and debugging.
Incoming Frame	The frame data currently being written into a frame buffer in an AJA device’s SDRAM from its video input connector.
ISR	Interrupt Service Routine, usually a driver function that gets called by the host operating system “kernel” to handle an interrupt that may be relevant to the device being managed by the driver.
ISR	Also Interrupt Status Register, which exists on a peripheral device that indicates the state of the device at the conclusion of an interrupt-driven data transfer with another device or host.
Kick Sequence	A set of values written to a watchdog timer to prevent it from timing out.
LTC	Linear Time Code, a SMPTE standard for encoding timecode in an audio signal.
Loopback	An audio subsystem feature on NTV2 devices that, when enabled, the output embedder’s FIFO obtains audio samples directly from the audio subsystem’s input de-embedder FIFO, instead of from the audio subsystem’s output buffer.
MB86M31	HEVC/H.265 Real-time encoder hardware, developed by Socionext, a new company established by the consolidation of the System LSI businesses of Fujitsu Ltd and Panasonic Corp. This real-time 4K encoder is used in AJA HEVC-capable hardware and is supported in this SDK.
MSI	Message Signaled Interrupts — a more modern method of signaling an interrupt to a host computer from a PCI device using in-band messages instead of through dedicated interrupt lines.
OpenGL	Open Graphics Library, a cross-language, multi-platform API for rendering 2-D and 3-D vector graphics. It’s commonly used to achieve hardware-accelerated rendering using a host computer’s GPU.
Outgoing Frame	The frame data currently being read out of a frame buffer in an AJA device’s SDRAM and sent to its video output connector.
PCI	Peripheral Component Interconnect, a standardized expansion bus for attaching hardware devices to a host computer.
PCIe	Peripheral Component Interconnect Express, a high-speed serial expansion bus used to attach hardware devices to a host computer, and be able to transfer data between the host and the device, or between PCIe devices that share the bus.
PCM	Pulse Code Modulation, a method of digitally encoding sampled analog signals, most typically audio signals. The amplitude of the signal is sampled at regular time intervals, with each sample quantized to the nearest discrete value.
PIO	Programmed Input / Output, a relatively slow and archaic method of transferring data between a peripheral device and the host computer it’s attached to.
PSF	Acronym for Progressive Segmented Frame, a scheme for dividing a single progressive (full) frame into two fields of even and odd lines, just as in interlaced video, but with no time elapsed (or content motion) between the two fields.
RAM	Acronym for Random Access Memory.
Relay	An electrical switch whose position is controlled by another independent electrical signal. The switch has a default position when no power or signal is applied to its control input.
RP-188	A SMPTE standard for encoding and conveying timecode over SDI.
SD	Standard Definition television standards: i.e. NTV2_STANDARD_525 and NTV2_STANDARD_625.
SDI	Serial Digital Interface, a family of video interfaces standardized by SMPTE for transferring video and audio data between two machines.
SDRAM	Synchronous Dynamic Random Access Memory, a type of random access memory that is refreshed dynamically every clock cycle on the PCI bus.
SFP	Small Form-factor Pluggable transceiver, a hot-pluggable optical connector used to connect to high-speed IP communications networks.
SMPTE	Society of Motion Picture and Television Engineers, the body that governs most of the standards used in digital video/audio signal transmission.
Thunderbolt	A hardware interface developed by Intel that’s used to connect external peripheral devices to a computer, which combines PCI Express and DisplayPort signals into a single serial cable, including DC power, using a Mini DisplayPort connector.
Timecode	A sequence of numeric codes generated at regular intervals by a timing system.
Transfer Frame	Identifies the frame being transferred from host memory to the AJA device’s frame buffer memory (when playing out), or from the AJA device’s frame buffer memory to host memory (when capturing).
VANC	Vertical Ancillary Data, is ancillary data that, for each field (interlaced) or frame (progressive), is embedded into the video lines that precede the first line of active video.
VBI	Vertical Blanking Interval, which is the length of time between the end of the last line of a video field/frame and the start of the first line of the next frame/field.
VBI	Also Vertical Blanking Interrupt, which signals the AJA device driver when the next field or frame should be handled by AutoCirculate.
VPID	Video Payload IDentifier – A 4-byte packet of ancillary data that describes the format of video data being transferred over a physical SDI cable.
Watchdog Timer	A circuit that will change its state after a specified time interval has elapsed, unless a value is written to it that restarts the time interval. The state change can cause an action to occur, such as putting a device into bypass.