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Method and system for low-delay video mixing

A video mixing and video technology, used in video conference systems, TV system components, transmission systems, etc.

Inactive Publication Date: 2007-12-26
NOKIA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These decoding and re-encoding steps introduce a delay between sending and receiving the compressed video stream

Method used

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  • Method and system for low-delay video mixing
  • Method and system for low-delay video mixing
  • Method and system for low-delay video mixing

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no. 2 example

[0153] This embodiment is relevant to the mixing of asynchronous sources in a potentially error-prone environment. When the frame rates of the sending terminals are different (for example, some sending terminals are in the PAL (Phase Alternation Line) domain and others are in the NTSC (National Television Standards Committee) domain), or when frames are skippable, or when frames in transmission This is the case when damaged or lost. Blending is more complicated.

[0154] In such an environment, during conference initiation, the mixer must signal to the receiving terminal a maximum frame rate that is equal to or higher than the highest of the rates used by the sending terminal. Alternatively, during the capability exchange, the mixer may force the sending terminal to a frame rate that is lower than or equal to the frame rate supported by the receiving endpoint.

[0155] Once it is established that the receiving endpoint is "faster" or at least "as fast" as the "fastest" sendi...

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Abstract

A method and system for compressed domain video mixing for spatially combining incoming video streams into an outgoing video stream. Using H.264 as an example, each incoming stream is divided into a plurality of slices, each having a plurality of header fields including a first_mb_in_slice header field. Based on the picture format in the outgoing stream, first_mb_in_slice for each incoming stream is modified such that the modified first_mb_in_slice header field is indicative of location in the spatial representation of the outgoing stream at which the slice of the incoming stream is placed. H.264's slice group mechanism is used to map the spatial positions of the second and following macroblocks of the slices to the appropriate locations. If the incoming streams are previously mixed by upstream mixers, a decomposer can be used to separate these mixed streams into component streams before combining them with other incoming streams.

Description

technical field [0001] The present invention relates to video mixers in real-time sensitive communication systems, such as multipoint control units (MCUs) used in video conferencing systems, and to a system and method of picture decomposition to form an inverse mixing process. Background technique [0002] Traditionally, a video conferencing endpoint is designed to connect to another remote video conferencing endpoint in a point-to-point fashion. As depicted in FIG. 1 , the sending endpoint 102 includes a dynamic video source 101 such as a camera and an encoder 103 for encoding video images from the video source into a video compressed stream. The video compressed stream is then sent by network 105 to a single receiving endpoint 106 via network interface 104 . The receiving endpoint 106 includes a network interface 107 , a decoder 108 and a display device 109 . Encoder 103 and decoder 108 typically conform to a known video compression format, such as H.264. In this way, t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N7/15H04N5/265
CPCH04L29/06503H04N19/00272H04N7/152H04L65/605H04L29/06421H04N19/00472H04L29/06027H04L65/4038H04N19/174H04N19/40H04L65/765H04L65/1101
Inventor S·文格尔M·阿尼克瑟拉
Owner NOKIA CORP