Signal coding method, signal coding apparatus, signal recording medium, and signal transmission method

• US 6,363,114 B1
• Filed: 04/16/1998
• Issued: 03/26/2002
• Est. Priority Date: 04/30/1997
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kato, Motoki
• Primary Examiner(s): Kelley, Chris
• Assistant Examiner(s): An, Shawn S.
• Application Number:
  US09/061,581
• Time in Patent Office: 1,440 Days
• Field of Search: 375/240, 375/240.03, 375/240.04, 348/384, 348/699, 348/390, 348/405, 348/402, 348/416, 386/112, 386/111, 386/109
• US Class Current: 375/240.04
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/177 the unit being a group of pictures [GOP]
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence

Abstract

A signal coding method and apparatus enables effective coding of a predetermined time segment of a video signal with a variable bit rate at real time (one-path) into a total coding bit amount of a constant data capacity. A coding difficulty calculator 13 determines a coding difficulty of an input signal for each unit time. An allocation bit amount calculator 14 interrelates an allocation data amount with a coding difficulty for each unit time standardized in advance using an ordinary input signal of the type to which the input signal belongs, so as to obtain a reference value of the allocation data amount for each unit time interrelated with the coding difficulty supplied from the coding difficulty calculator 13. This reference value of the allocation data amount is modified by a controller 15 into an actual allocation data amount, according to which the input signal is coded by a moving picture image coding apparatus 18, so as to create coded data.

Claims

1. A signal coding method comprising the steps of:

determining a coding difficulty for each unit time of an input signal;

interrelating an allocation data amount for each unit time with a coding difficulty which has been standardized in advance using an ordinary input signal of the type to which said input signal belongs, so as to obtain a reference value of said allocation data amount interrelated with said coding difficulty of said input signal for said each unit time;

modifying said reference value of said allocation data amount into an actual allocation data amount; and

generating coded data by coding said input signal for said each unit time according to said actual allocation data amount;

wherein said step of modifying said reference value of said allocation data amount into an actual allocation data amount is characterized in that a total B av of allocation bit amount up to a current time is compared to a total B gen of actually generated coding bit amount up to the current time while coding the input signal for each unit time with a constant allocation bit amount b av, and if a value (B av−

B gen) is positive, it is allowed to assign an allocation bit amount equal to or above b av which is defined as follows;

2. A signal coding method as claimed in claim 1, wherein when coding a signal and recording the coded signal onto a recording medium several times, said value (B av−

B gen) or a value equivalent to said value is recorded on said recording medium, so that when a signal is recorded in an empty area of said recording medium a subsequent time, prior to signal recording, said value (B av−

B gen) or the value equivalent to said value is read out from said recording medium, according to which value an allocation bit amount of an input signal is calculated for each unit time.

3. A signal coding apparatus comprising:

coding difficulty calculating means for determining a coding difficulty for each unit time of an input signal;

allocation data amount reference value calculating means for interrelating an allocation data amount for each unit time with a coding difficulty which has been standardized in advance using an ordinary input signal of the type to which said input signal belongs, so as to obtain a reference value of said allocation data amount interrelated with said coding difficulty of said input signal for said each unit time;

means for modifying said reference value of said allocation data amount into an actual allocation data amount; and

coding means for generating coded data by coding said input signal for said each unit time according to said actual allocation data amount;

wherein said means for modifying said reference value of said allocation data amount into an actual allocation data amount is characterized in that a total B av of allocation bit amount up to a current time is compared to a total B gen of actually generated coding bit amount up to the current time while coding the input signal for each unit time with a constant allocation bit amount b av, and if a value (B av−

B gen) is positive, it is allowed to assign an allocation bit amount equal to or above b av which is defined as follows;

4. A signal recording medium on which a coded signal is to be recorded, wherein said coded signal is obtained by:

determining a coding difficulty for each unit time of an input signal;

interrelating an allocation data amount for each unit time with a coding difficulty which has been standardized in advance using an ordinary input signal of the type to which said input signal belongs, so as to obtain a reference value of said allocation data amount interrelated with said coding difficulty of said input signal for said each unit time;

modifying said reference value of said allocation data amount into an actual allocation data amount; and

creating coded data by coding said input signal for said each unit time according to said actual allocation coding amount;

wherein said step of modifying said reference value of said allocation data amount into an actual allocation data amount is characterized in that a total B av of allocation bit amount up to a current time is compared to a total B gen of actually generated coding bit amount up to the current time while coding the input signal for each unit time with a constant allocation bit amount b av, and if a value (B av−

B gen) is positive, it is allowed to assign an allocation bit amount equal to or above b av which is defined as follows;

5. A signal recording medium as claimed in claim 4, wherein when coding a signal and recording the coded signal onto a recording medium several times, said value (Bav−

B gen) or a value equivalent to said value is recorded on said recording medium, so that when a signal is recorded in an empty area of said recording medium a subsequent time, prior to signal recording, said value (B av−

B gen) or the value equivalent to said value is read out from said recording medium, according to which value an allocation bit amount of an input signal is calculated for each unit time.

6. A signal transmission method comprising:

determining a coding difficulty for each unit time of an input signal;

obtaining a reference value of allocation data amount interrelated with said coding difficulty of said input signal for said each unit time based on a standardized relationship between coding difficulty and allocation data amount, wherein said standardized relationship is provided when a reference motion picture image sequence is coded by way of variable bit rate coding with a predetermined average bit rate;

modifying said reference value of said allocation data amount into an actual allocation data amount;

generating coded data by coding said input signal for said each unit time according to said actual allocation data amount; and

transmitting said generated coded data;

wherein said step of modifying said reference value of said allocation data amount into an actual allocation data amount is characterized in that a total B av of allocation bit amount up to a current time is compared to a total B gen of actually generated coding bit amount up to the current time while coding the input signal for each unit time with a constant allocation bit amount b av, and if a value (B av−

B gen) is positive, it is allowed to assign an allocation bit amount equal to or above b av which is defined as follows;