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1.1 Glossary

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This document uses the following terms:

B-frame: A bidirectional video frame that references both the previous frame and the next frame.

big-endian: Multiple-byte values that are byte-ordered with the most significant byte stored in the memory location with the lowest address.

cached frame: A video frame that is cached for later use by an encoder and a decoder. A cached frame acts as a reference frame for the next Super P-frame (SP-frame). I-frames and SP-frames typically are cached frames.

endpoint: A device that is connected to a computer network.

entry point header: A header field whose values specify the horizontal and vertical dimensions of a video frame. See also sequence header.

forward error correction (FEC): A process in which a sender uses redundancy to enable a receiver to recover from packet loss.

GOP: A group of pictures that starts with one I-frame and ends with the next I-frame, excluding the next I-frame, as described in [SMPTE-VC-1].

I-frame: A video frame that is encoded as a single image, such that it can be decoded without any dependencies on previous frames. Also referred to as Intra-Coded frame, Intra frame, and key frame.

maximum transmission unit (MTU): The size, in bytes, of the largest packet that a given layer of a communications protocol can pass onward.

network byte order: The order in which the bytes of a multiple-byte number are transmitted on a network, most significant byte first (in big-endian storage). This does not always match the order in which numbers are normally stored in memory for a particular processor.

P-frame: A predicative video frame that references a previous frame. Also referred to as inter-coded frame or inter-frame.

Real-Time Transport Protocol (RTP): A network transport protocol that provides end-to-end transport functions that are suitable for applications that transmit real-time data, such as audio and video, as described in [RFC3550].

RTP packet: A data packet consisting of the fixed RTP header, a possibly empty list of contributing sources, and the payload data. Some underlying protocols could require an encapsulation of the RTP packet to be defined. Typically one packet of the underlying protocol contains a single RTP packet, but several RTP packets can be contained if permitted by the encapsulation method. See [RFC3550] section 3.

RTP payload: The data transported by RTP in a packet, for example audio samples or compressed video data. For more information, see [RFC3550] section 3.

RTVC1: A Microsoft proprietary implementation of the VC1 codec for real-time transmission purposes, as described in [SMPTE-VC-1]. Microsoft extensions to VC1 are based on cached frame and SP-frame, as described in [MS-RTVPF].

RTVideo: A video stream that carries an RTVC1 bit stream.

RTVideo FEC metadata packet: A packet that is generated by using the forward error correction (FEC) algorithm to provide redundancy. It is packetized in the RTVideo FEC Real-Time Transport Protocol (RTP) payload format.

RTVideo frame: A video frame that is encoded by using an RTVC1 codec.

sequence header: A set of encoding and display parameters that are placed before a group of pictures, as described in [SMPTE-VC-1]. See also entry point header.

Super P-frame (SP-frame): A special P-frame that uses the previous cached frame instead of the previous P-frame or I-frame as a reference frame.

video data packet: A video data block that encapsulates a complete video frame or a fragment of a video frame. It contains the video payload header and the video payload.

MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.