Data stream protocol for multimedia data streaming data processing system

• US 5,339,413 A
• Filed: 08/21/1992
• Issued: 08/16/1994
• Est. Priority Date: 08/21/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Winters, Scott L., Lawton, William W., Tyler, John G., Koval, Michael J.
• Primary Examiner(s): Heckler, Thomas M.
• Application Number:
  US07/934,069
• Time in Patent Office: 725 Days
• Field of Search: 395/154, 395/650, 395/250
• US Class Current: 719/314
• CPC Class Codes: G06F 13/387 for adaptation of different data processing systems to different peripheral devices, e.g. protocol converters for incompatible systems, open system

Abstract

A data stream is created for moving data from a source to a target in accordance with a stream protocol defined by controlling stream protocol control blocks (SPCBs) created from a predefined source SPCB and a predefined target SPCB. The controlling SPCBs include information establishing a plurality of data buffers that are used to efficiently stream or transfer data on a real-time basis. The controlling SPCBs are formed by a process of negotiation in which differences between the source and target SPCBs are reconciled in accordance with rules of negotiation. Once the data stream is created, it is then started by the application program and data is streamed until an end of stream is reached.

Claims

1. In a multimedia data processing system comprising a personal computer having processor and a storage system, said storage system including a memory for storing at least one multimedia application program and a multitasking operating system for execution by said processor, data streaming apparatus operable under said operating system and said application program for streaming data from a source device to a target device in accordance with a streaming protocol, said apparatus comprising:

a plurality of programmable stream handlers stored in said storage system and including at least one source stream handler and at least one target stream handler;

a plurality of predefined streaming protocol control blocks (SPCBs) stored in said storage system and including a first SPCB for said source stream handler and a second SPCB for said target stream handler;

each of said predefined SPCBs containing a plurality of fields for storing stream protocol parameters including data type, number of buffers needed to maintain continuous streaming of data, and size of buffers;

said source stream handler comprising a callable first routine for creating a source thread as a task under said operating system and blocking such source thread, and a callable second routine for unblocking said source thread and streaming data from said source device to said buffers;

said target stream handler comprising a callable third routine for creating a target thread as a task under said operating system and blocking such target thread, and a callable fourth routine for unblocking said target thread and streaming data from said buffers to said target device;

and stream manager means operable in response to execution of a stream create call instruction in said application program, to create a data stream by

calling said first routine and said third routine to set up source and target threads as multitask threads under said operating system and block on such threads,

creating a negotiated source SPCB and a negotiated target SPCB by negotiating differences between said first and second SPCBs, said negotiated source SPCB and said negotiated target SPCB defining a negotiated streaming protocol mutually acceptable to both said source handler and said target handler,

and dynamically allocating in said memory a plurality of buffers for said data stream in accordance with said streaming protocol defined in said negotiated source and target SPCBs.

2. A multimedia data processing system in accordance with claim 1 wherein:

said stream manager means is operable in response to execution of a start stream call in said application program, to call said second and fourth routines to initiate data streaming and transfer data in accordance with said negotiated streaming protocol.

3. A multimedia data processing system in accordance with claim 2 wherein said stream protocol parameters include a plurality of buffer attribute flags, a plurality of data attribute flags, and a plurality of stream handler flags.

4. A multimedia data processing system in accordance with claim 3 wherein:

said stream manager means is operative to produce said negotiated SPCBs by selecting parameters from said first and second SPCBs in accordance with predefined rules of negotiation.

5. A multimedia data processing system in accordance with claim 4 wherein said data type parameters in said first and second SPCBs may be specified as a generic data type or as a specific data type, and said data type parameters in said negotiated SPCBs are set in accordance with said rules of negotiation to a generic type when either one of said first or second SPCBs specifies a generic data type and to a specific data type when both of said first and second SPCBs specify the same specific data type.

6. A multimedia data processing system in accordance with claim 5 wherein said system manager means produces an error indication when said first and second SPCBs specify different specific data types.

7. A multimedia data processing system in accordance with claim 4 wherein said data attribute flags indicate whether data or time cue points and seeking are supported by data type set forth in said negotiated SPCBs.

8. A multimedia data processing system in accordance with claim 7 wherein a SPCBHAND_-- PHYS_-- SEEK flag is used to specify if a stream handler does a physical device seek when called, said stream manager means being operative to first call such stream handler when said SPCBHAND_-- PHYS_-- SEEK flag is set.

9. A multimedia data processing system in accordance with claim 4 wherein said stream handler flags indicate whether each stream handler can participate in synchronization by receiving or generating sync pulses, or without streaming.

10. A multimedia data processing system in accordance with claim 8 wherein for sync pulses, each handler must specify whether it can send or receive sync pulses by setting SPCBHAND_-- GENSYNC and SPCBHAND_-- RCVSYNC flags, and in accordance with said rules of negotiation said target stream handler is set as a default generator/receiver of sync pulses unless only the source can generate/receive sync pulses.

11. A multimedia data processing system in accordance with claim 4 wherein said buffer attribute flags indicate user provided buffers, fixed block size, interleaved data type, and maximum buffer size.

12. A multimedia data processing system in accordance with claim 4 wherein said negotiated SPCBs contain size of buffer parameters that are set to the greater one of the size of buffer parameters contained in said first SPCB and said second SPCB.

13. A multimedia data processing system in accordance with claim 4 wherein said fields in said negotiated source SPCB include a field for specifying a maximum number of records per buffer which field is obtained for split streams from said first SPCB and is a value greater than 0.

14. A multimedia data processing system in accordance with claim 4 wherein said negotiated SPCBs include fields specifying the number of empty buffers required to start said source thread which number is always taken from said first SPCB, and said negotiated SPCBs further include fields specifying the number of full buffers required to start said target thread which number is always taken from said second SPCB.

15. A multimedia data processing system in accordance with claim 2 wherein:

said stream manager means is further operable in response to execution of said start stream call to call said second routine to fill a plurality of buffers with data from said source device, and to thereafter call said fourth routine to empty such filled buffers, said second routine and said fourth routine being thereafter operable to run both threads to alternately fill buffers with data and write data from said buffers until an end of data stream is reached.

16. A multimedia data processing system in accordance with claim 15 wherein said source handlers are operative to initially block said threads after said threads have been set up, and to thereafter unblock said threads in response to said start stream call thereby allowing said threads to transfer said data through said buffers.

17. A multimedia data processing system in accordance with claim 16 wherein said stream manager means controls use of said buffers by said threads whereby said stream manager means provides empty buffers to said source thread for filling with data from said source device, receives filled buffers from said source thread, provides filled buffers to said target thread for writing data therefrom to said target device, and receives empty buffers from said target thread.

18. A multimedia data processing system in accordance with claim 2 wherein said memory is a paged memory;

and said apparatus includes means operative after said buffers have been allocated to lock said buffers in said memory to prevent said buffers from being paged out while data streaming is occurring.