RTP Payload Format for H.263 Video Streams (RFC2190)
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2019-Feb-15
Internet Society Requests For Comment (RFCs)
This document specifies the payload format for encapsulating an H.263 bitstream in the Real-Time Transport Protocol (RTP). [STANDARDS-TRACK]
Network Working Group C. Zhu Request for Comments: 2190 Intel Corp. Category: Standards Track September 1997
RTP Payload Format for H.263 Video Streams
Status of This Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
This document specifies the payload format for encapsulating an H.263 bitstream in the Real-Time Transport Protocol (RTP). Three modes are defined for the H.263 payload header. An RTP packet can use one of the three modes for H.263 video streams depending on the desired network packet size and H.263 encoding options employed. The shortest H.263 payload header (mode A) supports fragmentation at Group of Block (GOB) boundaries. The long H.263 payload headers (mode B and C) support fragmentation at Macroblock (MB) boundaries.
This document describes a scheme to packetize an H.263 video stream for transport using RTP . H.263 video stream is defined by ITU-T Recommendation H.263 (referred to as H.263 in this document)  for video coding at very low data rates. RTP is defined by the Internet Engineering Task Force (IETF) to provide end-to-end network transport functions suitable for applications transmitting real-time data over multicast or unicast network services.
The following definitions apply in this document:
CIF: Common Intermediate Format. For H.263, a CIF picture has 352 x 288 pixels for luminance, and 176 x 144 pixels for chrominance.
QCIF: Quarter CIF source format with 176 x 144 pixels for luminance and 88 x 72 pixels for chrominance.
Sub-QCIF: picture source format with 128 x 96 pixels for luminance and 64 x 48 pixels for chrominance.
Zhu Standards Track [Page 1]
RFC 2190 RTP Payload Format for H.263 Video Streams September 1997
4CIF: Picture source format with 704 x 576 pixels for luminance and 352 x 288 pixels for chrominance.
16CIF: Picture source format with 1408 x 1152 pixels for luminance and 704 x 576 pixels for chrominance.
GOB: For H.263, a Group of Blocks (GOB) consists of k*16 lines, where k depends on the picture format (k=1 for QCIF, CIF and sub- QCIF; k=2 for 4CIF and k=4 for 16CIF).
MB: A macroblock (MB) contains four blocks of luminance and the spatially corresponding two blocks of chrominance. Each block consists of 8x8 pixels. For example, there are eleven MBs in a GOB in QCIF format and twenty two MBs in a GOB in CIF format.
3. Design Issues for Packetizing H.263 Bitstreams
H.263 is based on the ITU-T Recommendation H.261  (referred to as H.261 in this document). Compared to H.261, H.263 employs similar techniques to reduce both temporal and spatial redundancy, but there are several major differences between the two algorithms that affect the design of packetization schem...