Moving image encoding apparatus

• US 20020172283A1
• Filed: 06/06/2002
• Published: 11/21/2002
• Est. Priority Date: 12/14/1999
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kawakatsu, Hirokazu, Asano, Atsushi
• Granted Patent: US 6,907,072 B2
• Time in Patent Office: Days
• US Class Current: 375/240.13
• CPC Class Codes: H04L 1/0014 by adapting the source coding
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/166 concerning the amount of transmission errors, e.g. bit error rate [BER]
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/192 the adaptation method, adaptation tool or adaptation type being iterative or recursive
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

In a moving image encoding apparatus of this invention, a generated bit amount extracting section (21) counts generated bits of variable-length-encoded data in units of macroblocks, and a reference generated bit count is set in a parameter value control section (22) as an update condition for a parameter value in each block. The boundary value of the parameter value is set in an intra/inter determination section (23) as a criterion for selection of the intra-encoding mode. In the inter-frame encoding mode, the parameter value control section (22) updates the parameter value of a block in which the generated bit count value of encoded data obtained by the generated bit amount extracting section (21) exceeds a reference value. The intra/inter determination section (23) determines that the influence of a data error is large in a block in which the parameter value is continuously updated and exceeds the boundary value, and switches the current mode to the intra-encoding mode to perform refresh operation.

Claims

1. A moving image encoding apparatus including

block generating means (12) for receiving moving image data in units of frames, dividing the received data into a plurality of blocks, and outputting the data of the respective blocks in a predetermined order, and

mode-specific encoding means (11, 13-20), having intra-encoding mode and inter-frame encoding mode, for encoding in a designated mode the data of the respective blocks sequentially output from said block generating means, characterized by comprising:

information extraction means (21, 24) for extracting information for determination of a degree of influence of a data error from an encoded block processed by said mode-specific encoding means (11, 13-20);

parameter value control means (22) for, when intra-encoding is performed by said mode-specific encoding means (11, 13-20), setting an initial value as a parameter value of a corresponding block in advance, comparing the information extracted by said information extraction means (21, 24) with a predetermined reference value, and updating and storing the parameter value on the basis of the comparison result; and

intra/inter determination means (23) for, when data of a block of a next frame, output from said block generating means (11), is to be encoded, comparing a parameter value of a corresponding block, stored in said parameter value control means (22), with a predetermined boundary value, determining on the basis of the comparison result whether to execute refresh by intra-encoding, and designating a mode based on the determination result with respect to said mode-specific encoding means (11, 13-20).

2. An apparatus according to claim 1, characterized in that said mode-specific encoding means (11, 13-20) encodes pixel components in an input frame in units of blocks without performing motion compensation prediction in the intra-encoding mode, and obtaining difference values between an original image and a motion compensation predicted image obtained by motion compensation prediction and encoding the difference values in units of blocks in the inter-frame encoding mode.

3. An apparatus according to claim 1, characterized in that said information extraction means (21) extracts a generated encoded data amount from an encoded output from said mode-specific encoding means as information for determination of the degree of influence of the data error.

4. An apparatus according to claim 1, characterized in that when said mode-specific encoding means (11, 13-20) performs discrete cosine transform processing for block data, said information extraction means (24) extracts a total number of non-zero coefficients of coefficients obtained by the discrete cosine transform processing as information for determination of the degree of influence of the data error.

5. An apparatus according to claim 1, characterized by further comprising reference value/boundary value changing means (25) for detecting an error rate in a transmission path, and changing at least one of a reference value held in said parameter value control means and a boundary value held in said intra/inter determination means (23) on the basis of the detected error rate.

6. An apparatus according to claim 1, characterized by further comprising:

encoded data storage means (26) for storing encoded data output from said mode-specific encoding means (11, 13-20) in units of blocks; and

reference value/boundary value changing means (27) for obtaining an encoded data amount stored in said means (26), and changing at least one of a reference value held in said parameter value control means and a boundary value held in said intra/inter determination means (23) on the basis of the encoded data amount.

7. An apparatus according to claim 1, characterized in that said parameter value control means (22) adds one to the parameter value when information extracted by said information extraction means is larger than a reference value, and adds 0 to the parameter value otherwise.