Video storage

• US 6,404,975 B1
• Filed: 04/14/1997
• Issued: 06/11/2002
• Est. Priority Date: 04/15/1996
• Status: Expired due to Term

• Current Assignee: Autodesk, Inc.
• Original Assignee: Discreet Logic, Inc. (Autodesk, Inc.)
• Inventors: Bopardikar, Raju C., Braine, Adrian R.
• Primary Examiner(s): Boccio, Vincent F.
• Application Number:
  US08/843,282
• Time in Patent Office: 1,884 Days
• Field of Search: H04/N.591, 386/4, 386/21, 386/45-46, 386/52, 386/64, 386/113, 386/116, 386/125-126, 360/13, 360/15-17, 369/83-85, 348/7, 348/1-6, 348/8-14, 714/6-7
• US Class Current: 386/241
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence
• CPC Class Codes: G11B 2220/415 Redundant array of inexpensive disks [RAID] systems
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/34 Indicating arrangements indicating means incorporated in magazine or cassette G11B23/046 and G11B23/0875; indicating measured values in general G01D
• CPC Class Codes: H04N 11/20 Conversion of the manner in which the individual colour picture signal components are combined, e.g. conversion of colour television standards
• CPC Class Codes: H04N 21/2182 involving memory arrays, e.g. RAID disk arrays RAID arrays per se G06F3/0689; use of parity to protect data in RAID systems G06F11/1008
• CPC Class Codes: H04N 5/262 Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects ; Cameras specially adapted for the electronic generation of special effects
• CPC Class Codes: H04N 5/781 on disks or drums
• CPC Class Codes: H04N 5/945 for signals recorded by pulse code modulation

Abstract

Video data in the form of a plurality of digitised frames, is stored on a plurality of magnetic disks. Each image frame is striped across a plurality of disks and redundant parity information, derived from the stripes, is written to an additional disk. Disk failure is detected and in response to this detection missing data is regenerated from the parity information. This allows the transfer of video data in real time to be maintained for output so that the system remains operational. While data is being read in real time, derived-from regenerated data, the regenerated data is written to an operational disk, thereby reprotecting the data in the event of a subsequent failure. Frame supplied to output are labelled as being protected or unprotected and application programs may respond to this status information as considered appropriate.

Claims

1. Video storage apparatus comprising storage means, transfer means and processing means, wherein

said storage means comprises a plurality of storage devices configured to store respective stripes of image frames with redundant data derived from said stripes,

said transfer means is arranged to transfer image data at image display rate at or at a rate greater than said display rate,

said processing means is configured to regenerate lost data from said redundant data during a reading operation to provide output data to a compositing process and to write said regenerated data to an operational storage device while said output data is being supplied to said compositing process while maintaining said rate;

and

wherein said processing means writes the regenerated data to the operational storage device using bandwidth normally allocated during on-line operation for reading data from a storage device that contained the lost data and that has become non-operational.

2. Apparatus according to claim 1, wherein said storage devices are magnetic disks.

3. Apparatus according to claim 2, wherein each stripe is written to a respective disk and said redundant data is written separate disk.

4. Apparatus according to claim 3, wherein said redundant data is parity data derived by an exclusive ORing operation.

5. Apparatus according to claim 1, wherein output data is written to a frame buffer.

6. Apparatus according to claim 5, wherein two output frame buffers alternate in operation, to effect double buffering in which a first buffer is written to randomly from the storage devices and a second buffer is read sequentially as a synchronized video stream.

7. Apparatus according to claim 6, wherein said video stream is compatible with D1 video recommendation.

8. Apparatus according to claim 1, wherein said processing means detects data errors and initiates data regeneration in response to said detection.

9. Apparatus according to claim 1, wherein a spare drive is maintained in an array to receive regenerated data.

10. Apparatus according to claim 1, wherein said processing means is configured to label image frames as being protected or as being unprotected.

11. Apparatus according to claim 1, wherein said processing means is configured to perform additional regeneration of data not requested for output during relatively idle periods.

12. Apparatus according to claim 1, wherein said processing means is configured to detect disk imbalance conditions after data has been regenerated.

13. A method of storing video data, wherein image stripes derived from image frames in combination with redundant data derived from said stripes are stored on a plurality of storage devices,

image data is transferred at substantially image display rate or at a rate greater than said display rate,

lost data is regenerated from said redundant data during a reading operation, and

said regenerated data is written to an operational storage device while output data is being supplied at said transfer rate while maintaining said rate, wherein the regenerated data is written to the operational storage device using bandwidth normally allocated during on-line operation for reading data from a storage device that contained the lost data and that has become non-operational.

14. A method according to claim 13, wherein errors are detected during the replay of video data and data regeneration is initiated in response to said detection.

15. A method according to claim 13, wherein output image frames are labelled as being protected or as being unprotected, wherein an unprotected label indicates that data has been regenerated.

16. A method according to claim 13, wherein additional regeneration of data is effected during idle periods.

17. A method according to claim 13, including procedures for detecting disk imbalance conditions after data has been regenerated.

18. A method according to claim 13, wherein said video data is derived from cinematographic film.

19. A method according to claim 13, wherein said video data is derived from high definition video frames.

20. A method according to claim 13, wherein said video data is derived from broadcast video fields.

21. A video data storage system comprising:

storage devices for storing respective portions of a video data signal and redundancy data derived from the respective portions of the video data signal; and

a processing system configured to maintain normal on-line operation of said data storage system wherein a transfer rate of the video data signal is maintained at a normal transfer rate when one of said storage devices storing a portion of the video data signal becomes non-operational by regenerating video data stored on the non-operational storage device using the redundancy data,

said processing system being further configured to write the regenerated video data to an operational storage device while the normal transfer rate during on-line operation of said data storage system is maintained, wherein the portion of the video data signal stored on the non-operational storage device is at least partly healed while the normal on-line operation of said data storage system is maintained, and wherein the processing system writes the regenerated video data to the operational storage device using bandwidth normally allocated during on-line operation for reading video data from the storage device that has become non-operational.

22. A system according to claim 21, wherein the video data signal is a D1 video signal.

23. A system according to claim 21, wherein frames of the video data signal are divided into stripes and each stripe is stored on a respective corresponding one of said storage devices.

24. A system according to claim 23, wherein the redundancy data is parity data derived by logically combining the data supplied to said storage devices.

25. A system according to claim 24, wherein said processing system regenerates data by logically combining parity data and data from the operational storage devices.

26. A system according to claim 21, further comprising:

first and second frame buffers each of which is alternately operable for being written with data output from said storage devices and for being read to input data to said storage devices.

27. A method of operating a data storage system comprising storage devices, the method comprising:

storing on said storage devices respective portions of a video data signal and redundancy data derived from the respective portions of the video data signal;

maintaining a normal transfer rate of the video data signal during on-line operation of said data storage system when one of said storage devices storing a portion of the video data signal becomes non-operational by regenerating video data stored on the non-operational storage device using the redundancy data; and

writing the regenerated video data to an operational storage device while the normal transfer rate during on-line operation of said data storage system is maintained, whereby the portion of the video data signal stored on the non-operational storage device is at least partly healed while the on-line operation of said data storage system is maintained, and wherein the regenerated video data is written to the operational storage device using bandwidth normally allocated during on-line operation for reading data from a storage device that has become non-operational.

28. A method according to claim 27, wherein the video data signal is a D1 video signal.

29. A method according to claim 27, wherein frames of the video data signal are divided into stripes and each stripe is stored on a respective corresponding one of said storage devices.

30. A method according to claim 29, wherein the redundancy data is parity data derived by logically combining the data supplied to said storage devices.

31. A method according to claim 30, wherein the data is regenerated by logically combining parity data and data from the operational storage devices.