Browse Prior Art Database

Video Sub-band Coder

IP.com Disclosure Number: IPCOM000122420D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Galand, C: AUTHOR [+4]

Abstract

Traditionally, processing and coding of images and video sequences have been handled in two-dimensional (2-D) domain. However, 1-D processing combined with differential encoding (DPCM) can be as powerful as 2-D processing, while being less complex. The figure shows the block diagram of such a video coder. Each frame of the video sequence is encoded with reference to the decoded previous frame which is stored in a frame buffer. For each input line x(n), the corresponding line x'(n-1) from the decoded previous frame is subtracted, giving a difference line signal s(n) which is encoded with reference to the previously reconstructed difference line signal s'(n-1) of the current frame. The prediction error e(n) is quantized by 1-D sub-band coder (SBC), then decoded and used to compute the estimate of the next line.

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Video Sub-band Coder

      Traditionally, processing and coding of images and video
sequences have been handled in two-dimensional (2-D) domain. However,
1-D processing combined with differential encoding (DPCM) can be as
powerful as 2-D processing, while being less complex.  The figure
shows the block diagram of such a video coder. Each frame of the
video sequence is encoded with reference to the decoded previous
frame which is stored in a frame buffer. For each input line x(n),
the corresponding line x'(n-1) from the decoded previous frame is
subtracted, giving a difference line signal s(n) which is encoded
with reference to the previously reconstructed difference line signal
s'(n-1) of the current frame. The prediction error e(n) is quantized
by 1-D sub-band coder (SBC), then decoded and used to compute the
estimate of the next line.

      The 1-D SBC coder operates at a variable bit rate, which is
determined for each new line by the DAL (dynamic allocation of
levels) device.  This device dynamically allocates to each sub-band
the number of quantizing levels necessary to guarantee that the
overall signal- to-noise ratio is greater than a pre-specified value,
and that the average bit rate within each frame is constant on a
long-term basis.

      In steady-state operation, the DPCM loops remove the
inter-frame and intra-frame redundancies, and the combination of the
1-D SBC and of the DAL device allows to optimally allocate the coding
resources in the sub-b...