Dynamically linked and shared compression/decompression

• US 5,539,908 A
• Filed: 04/21/1995
• Issued: 07/23/1996
• Est. Priority Date: 11/24/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dorrance, Daniel M., Chen, Fetchi
• Primary Examiner(s): Kriess, Kevin A.
• Application Number:
  US08/428,783
• Time in Patent Office: 459 Days
• Field of Search: 395/700, 395/650, 395/600, 395/154
• US Class Current: 719/331
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

This invention discloses a software mechanism for installing and identifying compression/decompression procedures thereby providing dynamic linking, while also supporting existing and future CODEC algorithms. The present procedure is a dynamically linked library installed as an entry in the system initialization file. Each entry is comprised of a four character code which uniquely identifies a file format, a compression type, and a compression subtype. Additional CODEC information in the entry of the system initialization file are the file name, the procedure name, the processing speed, and other attributes of compression algorithms. This method combined with the installed entry in the initialization file allows sharing of the same CODEC algorithm for different file formats and also provides for an existing application program to continue working, without modification, even at such time as when a new CODEC algorithm is added to the file format in a future installation.

Claims

1. A computer implemented method for enabling a data processing system to support application software compression/decompression (CODEC) requirements, the method comprising the steps of:

installing a CODEC procedure in the data processing system;

identifying the CODEC procedure with a character code identifying attributes including file format for the CODEC procedure;

entering the character code identifying the installed CODEC procedure as an entry in an initialization file in the data processing system;

matching an application software attribute with a character code entry in the initialization file for an installed and identified CODEC procedure to identify a matched CODEC procedure required for the application software attribute; and

loading the identified matched CODEC procedure required for the application software attribute in the data processing system independent of the application software.

3. The method for enabling a data processing system to support application software CODEC requirements, as set forth in claim 1, wherein the step of identifying the CODEC procedure with a character code includes assigning a four character code for uniquely identifying each specific file format and compression attribute.

4. The method for enabling a data processing system to support application software CODEC requirements, as set forth in claim 3, wherein the step of identifying each specified file format and compression attribute includes identifying attributes or their combination, including compression type, compression subtype, CODEC library file name, CODEC procedure name and processing speed.

2. A computer implemented method for enabling a data processing system to support compression/decompression (CODEC) requirements of application software, the method comprising the steps of:

storing CODEC procedures in a linked library as entries in an initialization file for dynamic accessing by the application software in the data processing system;

identifying each entry in the linked library with a character code identifying CODEC procedure attributes of each entry; and

dynamically selecting one of the CODEC procedures from an entry in the linked library to carry out an application software requirement.

5. The method for enabling a data processing system to support CODEC requirements application software, as set forth in claim 2, further including the step of sharing of the CODEC procedures installed in the linked library by application softwares incorporating differing file formats such that a plurality of application softwares utilize the same CODEC procedure.

6. The method for enabling a data processing system to support CODEC requirements of application software, as set forth in claim 2, further including identifying each entry in the linked library with the character code comprising four characters and the step of dynamically linking the application software to one of the CODEC procedures in the absence of explicit CODEC procedure identification within the application software.

7. The method for enabling a data processing system to support CODEC requirements of application software, as set forth in claim 2, further including the steps of expanding the linked library to install another CODEC procedure installed subsequently to CODEC procedures initially installed.

8. The method for enabling a data processing system to support CODEC requirements of application software, as set forth in claim 2, wherein the step of identifying each installed CODEC procedure entry in the linked library includes identifying a different four character code identification and a CODEC procedure associated with different file formats, respectively, but with the same CODEC linked library file name and CODEC procedure name thereby providing for sharing of the same CODEC procedure for different file formats.

9. A computer implemented method for enabling a data processing system to support compression/decompression (CODEC) requirements of either a first or a second application software program during operation of one of the first or the second application software programs on the data processing system, the method comprising the steps of:

storing CODEC procedures in a linked library as entries in an initialization file for dynamic accessing by either the first or the second application software program in the data processing system;

identifying each entry in the linked library with a character code identifying CODEC procedure attributes of each entry;

dynamically selecting one of the CODEC procedures from an entry in the linked library to carry out a software requirement of either the first or the second application software program; and

expanding during operation of said one of the first or the second application software programs on the data processing system the linked library to install another CODEC procedure installed subsequently to CODEC procedures initially installed for dynamic accessing by either the first or the second application software program on the data processing system.