Method of and system for activity-based frequency weighting for FGS enhancement layers

• US 6,792,044 B2
• Filed: 05/16/2001
• Issued: 09/14/2004
• Est. Priority Date: 05/16/2001
• Status: Expired due to Term

• Current Assignee: Funai Electric Co., Ltd.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: van der Schaar, Minacia, Peng, Shaomin
• Primary Examiner(s): Kelley, Chris
• Assistant Examiner(s): Senfi, Behrooz
• Application Number:
  US09/859,781
• Publication Number:
  US 20020172279A1
• Time in Patent Office: 1,217 Days
• Field of Search: 348/398.1, 348/397.1, 348/438.1, 375/240.03, 375/240.01, 375/240.19, 375/240.15, 375/240.25, 375/240.16, 382/240, 382/248
• US Class Current: 375/240.03
• CPC Class Codes: H04N 19/29 involving scalability at the object level, e.g. video object layer [VOL]
• CPC Class Codes: H04N 19/33 in the spatial domain
• CPC Class Codes: H04N 19/34 Scalability techniques involving progressive bit-plane based encoding of the enhancement layer, e.g. fine granular scalability [FGS]

Abstract

The present invention provides methods and systems to determine the frequency weighting matrix that will provide the best image quality during MPEG4 FGS enhancement layer encoding, and to change this determination on a scene characteristics change basis, thereby optimizing the resulting output picture quality, especially in bandwidth-deprived applications.

Claims

1. A method of processing a video stream containing a plurality of video frames, in which said video stream is encoded by creating a base layer for each said frame, wherein said encoding includes a plurality of encoded blocks, and adding an enhancement layer, wherein the quantization residuals of said base layer forms a residual block to be further encoded to increase the fine granularity, said method comprising:

defining a plurality of frequency weighting matrix, each said matrix specifying the number of bit-plane shifts to apply to the coefficients of said residual blocks, in which one or more said matrix specifies a high weight and high width, and one or more said matrix specifies a high weight and medium width, one or more said matrix specifies low weight and low width, one or more said matrix specifies medium weight and high width, and one or more matrix specifies medium weight and medium width; and

encoding said base layer and encoding said enhancement layer, in which said enhancement layer is represented by a plurality of encoded residual blocks, wherein said encoded residual blocks are frequency-weighted with said frequency weighting matrix; and

when said video frame contains a high amount of motion, using said high weight and medium width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame;

or

when said video frame contains a high amount of activity, using said high weight and high width frequency weighting matrix to-determine said bit-plane shift to be applied to said blocks of said video frame;

or

when said video frame contains a low amount of motion and low amount of activity, using said low weight and low width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame;

or

when said video frame contains a lower amount of brightness, using said medium weight and high width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame;

or

otherwise, using said medium weight and medium width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame.

2. The method of claim 1, wherein said video stream is compressed using the MPEG-4 video compression standard.

3. The method of claim 1, wherein said enhancement layer of said encoded video stream is the fine granularity scalability enhancement layer coding of MPEG-4.

4. A system for processing a video stream, in which said video stream contains a plurality of video frames, in which said video stream is encoded by creating a base layer of each said video frame, and adding an enhancement layer, wherein the quantization residuals of said base layer forms a residual block to be further encoded to increase the fine granularity, and said processing includes a plurality of discrete cosine transform (“

DCT”

) encoded blocks, said system comprising;

a video signal source of said video stream; and

a processor operatively coupled to said video signal source, and an output for encoded video, said processor configured to;

define a plurality of frequency weighting matrix, each said matrix specifying the number of bit-plane shifts to apply to the coefficients of said residual blocks, in which one or more said matrix specifies a high weight and high width, and one or more said matrix specifies a high weight and medium width, one or more said matrix specifies low weight and low width, one or more said matrix specifies medium weight and high width, and one or more matrix specifies medium weight and medium width; and

encode said base layer and encode said enhancement layer, in which said enhancement layer is represented by a plurality of residual encoded blocks, wherein said residual encoded blocks are frequency-weighted with said frequency weighting matrix; and

when said video frame contains a high amount of motion, use said high weight and medium width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame;

or

when said video frame contains a high amount of activity, use said high weight and high width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame;

or

when said video frame contains a low amount of motion and low amount of activity, use said low weight and low width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame;

or

when said video frame contains a low amount of brightness, use said medium weight and high width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame;

or

otherwise, use said medium weight and medium width frequency weighting matrix to determine said bit-plane shift to be applied to said blocks of said video frame; and

place encoded enhancement layer video stream onto said encoded base layer to form a video output.

5. The system of claim 4, wherein said video stream is compressed using the MPEG-4 video compression standard.

6. The system of claim 4, wherein said enhancement layer of said encoded video stream is the fine granularity scalability enhancement layer coding of MPEG-4.