Browse Prior Art Database

Efficient Video Transmission of Delta/Realtime Frames

IP.com Disclosure Number: IPCOM000104816D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Key, A: AUTHOR [+2]

Abstract

Disclosed is a method of improving the uniformity of transmission rate the video is coded in terms of still and relative frames. Bandwidth efficiency is increased with benefits to fixed throughput communications pipeline systems and picture quality. Latency in realtime video links over commercial links due to buffering requirements of absolute and delta frames is overcome.

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Efficient Video Transmission of Delta/Realtime Frames

      Disclosed is a method of improving the uniformity of
transmission rate the video is coded in terms of still and relative
frames.  Bandwidth efficiency is increased with benefits to fixed
throughput communications pipeline systems and picture quality.
Latency in realtime video links over commercial links due to
buffering requirements of absolute and delta frames is overcome.

      This method applies to video compression techniques based on
absolute frames and delta frames.  It makes the load placed on a
communications system when transferring the live video data vary less
with time and allows the receiver of the video data to start
displaying a picture earlier when starting up.  Normal
frame/delta-frame systems transmit large (size in bytes) frames
followed by a few small deltas.  In the following description use is
made of a typical example of 1 frame, followed by 3 deltas which is
called a modulo 4 system, as frames appear every 4 packets.

     Load
      |
      |   __                      __
      |  |  |                    |  |
      |  |f |                    |f |
      |  |  |   __    __    __   |  |   __    __
      |  |  |  |d |  |d |  |d |  |  |  |d |  |d |
    _______________________________________________________ Time
      |  <-----> 1 frame time

In realtime videa transfer, it is important that the video frames,
absolute or delta, arrive at regular intervals, and with low latency;
i.e., buffering should not be used or used as little as possible.

      Therefore, to have a communications pipe of a certain
throughput, it must be able to transfer a whole absolute frame in 1
frame time, indicating that bandwidth is wasted when transmitting the
delta frames.  Also, when a new receiver of the video data stream
connects, it may have to ignore 0, 1, 2 or even 3 delta frames before
finding an absolute frame because decompression can only start from
absolute data.

      The first process of the scheme consists of dividing the video
image into 4 sub-images.  In any one 'frame' that is transmitted,
there is an absolute coding of one sub-image and delta information
for the other 3 sub-images.

      ___________    ___________    ___________    __________
     |  Abs.  A  |  | Delta A   |  | Delta A   |  | Delta A  |
     |           |  -------------  -------------  ------------
     |           |  | Abs.  B   |  | Delta B   |  | Delta B  |
     -------------  |      ...