Computer program product for selectively reducing bandwidth of real-time video data

• US 6,061,403 A
• Filed: 07/15/1999
• Issued: 05/09/2000
• Est. Priority Date: 06/10/1997
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Marino, Charles F.
• Primary Examiner(s): Le, Vu
• Application Number:
  US09/353,558
• Time in Patent Office: 299 Days
• Field of Search: 348/384, 348/390, 348/405, 348/419, 386/27, 386/33, 386/109, 386/111-112, 382/233, 345/202-203, 395/292-305, 364/715.02, 375/240
• US Class Current: 375/240
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• 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 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

Method, apparatus and computer program product are disclosed for selectively reducing the bandwidth of real-time video data for transmission on a bus having varying bandwidth, while minimizing perceptible loss of picture quality. After detecting an overflow condition within a buffer coupled to a bus, video data to be written to the buffer is discarded until a prior pending request for transmission of a pending block of video data from the buffer is granted and begun. After beginning the transmitting, the discarding of data is discontinued and new video data is written into the buffer. A next bus request is made for transmission of all remaining data in the buffer stored prior to detecting the overflow condition. The amount of discarded data in the line is monitored and used to determine an address for a new block of data stored after the discontinuity in the line of video data. Temporal redundancies between frames of a video image is employed to fill in the discontinuity in the line of video data by using correspondingly positioned data in a corresponding line of a prior frame or field.

Claims

1. A computer program product for processing a line of video data for transmission across a bus, the line of video data being temporarily written to a buffer, the buffer being coupled to the bus for reading of data in blocks from the buffer to the bus, said computer program product comprising:

(a) a computer usable medium having computer readable program code means embodied in said medium for causing a selective reduction in bandwidth of the line of video data, said computer program product having;

(i) computer readable program code means for causing said computer to detect an overflow condition within the buffer;

(ii) computer readable program code means for causing said computer to discard data from the line of video data being temporarily written to the buffer upon detecting said overflow condition;

(iii) computer readable program code means for causing said computer to transmit a pending block of video data from the buffer upon granting of a pending request for transmission of the pending block of video data from the buffer, said pending request being pending prior to said detecting (i), and upon beginning said transmitting, to discontinue said discarding of data from the line of video data being temporarily written to the buffer; and

(iv) computer readable program code means for causing said computer to provide at least one next bus request for transmission of at least one next block of video data from the buffer to the bus, said at least one next block of video data comprising all remaining video data in the buffer stored therein prior to said detecting of the overflow condition.

2. The computer program product of claim 1, further comprising computer readable program code means for causing said computer to determine an address for a new block of video data written to the buffer after said discontinuing (iii) discarding of data from the line of video data being written to the buffer.

3. The computer program product of claim 2, further comprising computer readable program code means for causing said computer to provide a new bus request for transmission of the new block of video data from the buffer across the bus.

4. The computer program product of claim 2, wherein said computer readable program code means for causing said computer to determine the address for the new block of video data comprises computer readable program code means for causing said computer to monitor said discarding (ii) to determine a discarded amount of data from said line of video data and to use said discarded amount of data to determine the address for the new block of video data as an offset from a starting address of the line of video data.

5. The computer program product of claim 1, further comprising computer readable program code means to cause said computer to set an overflow pending state upon detecting of the overflow condition and to reset said overflow pending state upon transmitting of the pending block of video data from the buffer to the bus.

6. The computer program product of claim 5, further comprising computer readable program code means for causing the computer to set an overflow inprocess state upon resetting the overflow pending state, and to reset the overflow in-process state upon transfer of the at least one next block of video data from the buffer to the bus subsequent to a granting of the at least one next bus request.

7. The computer program product of claim 5, further comprising computer readable program code means for causing said computer to set said overflow pending state if a further overflow condition is detected subsequent to beginning transmitting of the pending block of video data, and to repeat the computer processing of said computer readable program code means (i)-(iv).

8. At least one program storage device readable by a machine, tangibly embodying at least one program of instructions executable by the machine to perform a method of processing a line of video data for transmission across a bus, the line of video data being temporarily written to a buffer, the buffer being coupled to the bus for reading of data in blocks from the buffer to the bus, comprising:

(a) detecting an overflow condition within the buffer;

(b) upon detecting said overflow condition, discarding data from the line of video data being temporarily written to the buffer;

(c) upon granting of a pending request for transmission of a pending block of video data from the buffer, transmitting the pending block of video data from the buffer to the bus, said pending request being pending prior to said detecting (a), and upon beginning said transmitting, discontinuing said discarding (b) of data from the line of video data being temporarily written to the buffer; and

(d) providing at least one next bus request for transmission of at least one next block of video data from the buffer to the bus, said at least one next block of video data comprising all remaining video data in the buffer stored therein prior to said detecting (a) of the overflow condition.

9. The at least one program storage device of claim 8, further comprising determining an address for a new block of video data written to the buffer after said discontinuing (c) of said discarding of data from the line of video data being written to the buffer.

10. The at least one program storage device of claim 9, further comprising providing a new bus request for transmission of the new block of video data from the buffer.

11. The at least one program storage device of claim 9, wherein said determining an address comprises monitoring said discarding (b) to determine a discarded amount of data from said line of video data and using said discarded amount of data to determine the address for the new block of video data as an offset from a starting address of the line of video data.

12. The at least one program storage device of claim 8, further comprising repeating steps (b)-(d) for each overflow condition detected within the buffer.

13. The at least one program storage device of claim 8, further comprising setting an overflow pending state upon said detecting (a) of the overflow condition and resetting said overflow pending state upon transmitting (c) of the pending block of video data from the buffer to the bus.

14. The at least one program storage device of claim 13, further comprising setting an overflow in-process state upon resetting said overflow pending state, and resetting said overflow in-process state upon transfer of the at least one next block of video data from the buffer to the bus subsequent to a granting of the at least one next bus request of said providing (d).

15. The at least one program storage device of claim 13, further comprising setting said overflow pending state if a further overflow condition is detected subsequent to beginning said transmitting (c) of the pending block of video data, and repeating said steps (b)-(d).

16. The at least one program storage device of claim 8, wherein said line of video data comprises a line of a frame or a field of video data, and further comprising repeating said processing for each line of video data of said frame or field.

17. The at least one program storage device of claim 8, wherein said line of video data comprises one line of a frame or a field of video data, said discarding (b) creating gaps in said line of video data, and further comprising filling said gaps in said line of video data with video data in a corresponding position in a corresponding line of video data in a previous frame or a previous field.