Buffer controlled picture signal encoding and decoding system

• US 4,954,892 A
• Filed: 10/04/1989
• Issued: 09/04/1990
• Est. Priority Date: 02/14/1989
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Asai, Kohtaro, Murakami, Tokumichi, Matsuzaki, Kazuhiro
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Kostak, Victor R.
• Application Number:
  US07/416,984
• Time in Patent Office: 335 Days
• Field of Search: 358/431, 358/241.1, 358/133, 358/135, 358/136
• US Class Current: 375/240.23
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• 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 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer

Abstract

A picture signal encoding and decoding apparatus which transmits a digital picture signal by encoding, and receives and decodes an incoming encoded signal comprises a configuration in which a condition not to make a receiving buffer overflow can be controlled on the transmitting side, and a plurality of quantizers are prepared and a proper quantizing characteristic is selected and used according to the sequence of transformed coefficients and the size of a motion vector. Therefore, it is not necessary to prepare a receiving buffer of a large capacity or a high speed decoding circuit, so that the apparatus can be manufactured at a low cost and the stability of operation is improved and also a signal can be compressed efficiently owing to the realization of quantization corresponding to a statistical characteristic of an input signal.

Claims

1. A picture signal encoding and decoding apparatus having an encoding section for converting a series of picture elements whose number is predetermined (one picture frame or one line etc.) of a digitized picture signal series to a variable-length code-word series for transmission;

and a decoding section for receiving a transmitted encoded signal and converting the signal to a fixed-length signal and after that decoding the signal to a digital picture signal series;

said picture signal encoding and decoding apparatus comprising;

a transmitting buffer for performing speed conversion by storing data temporarily in order to transmit a sequence of said variable-length code-word series at a constant transmission rate;

a reference timing pulse generator being able to create reference timing pulses having an adjustable fixed period; and

a timing comparing and adjusting section for sensing the timing of head timing pulses positioned at the head of each of said variable-length coded-word series corresponding to said series of picture elements whose number is predefined which are read from said transmitting buffer and for determining the time difference between said head timing pulses and said reference timing pulses, and if said reference timing pulse is found to occur later than said head timing pulse, the magnitude of the time difference between said reference timing pulse and said head timing pulse is determined, and if the magnitude of said time difference is larger than a predetermined threshold value, the reading from said transmitting buffer is stopped and, after the insertion of dummy data, is then resumed to compensate for said time difference, and if said reference timing pulse is found to occur earlier than said head timing pulse, said reference pulse generator is reset to effect time adjustment to correct for the time difference between said reference timing pulse and head timing pulse whereby encoded-data series to be transmitted can be adjusted time-serially based on the reference timing given by said reference timing generator.

2. A picture signal encoding and decoding apparatus according to claim 1, wherein the period of said reference timing pulses corresponds to a time interval necessary to decode a fixed section of a picture signal on said decoding section side.