Disk-based digital video recorder

• US 6,526,225 B1
• Filed: 01/21/2000
• Issued: 02/25/2003
• Est. Priority Date: 09/21/1992
• Status: Expired due to Term

• Current Assignee: Grass Valley USA LLC (Vislink Technologies, Inc.)
• Original Assignee: Grass Valley USA LLC (Vislink Technologies, Inc.)
• Inventors: Casper, David, Murray, Scott, Greco, Anna, OʼConnor, Paul, Zamani, Elaine B., Windrem, Kevin D.
• Primary Examiner(s): NGUYEN, HUY THANH
• Application Number:
  US09/489,258
• Time in Patent Office: 1,131 Days
• Field of Search: 386/46, 386/68, 386/96, 386/104, 386/105, 386/112, 386/125, 711/114
• US Class Current: 386/265
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 12/0862 with prefetch
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• 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: H04N 5/781 on disks or drums
• CPC Class Codes: H04N 5/9261 involving data reduction

Abstract

A digital video recorder employing standard hard disk arrays employs a caching system to enable continuous video data to be supplied to and provided from the standard disk drives which may not be adapted for continuous data stream operation. The system is implemented as an array of disk drives and includes cache management functions for governing disk read and write operations. A predictor enables the cache to predict disk reads and disk writes and to maintain the cache based on the predictions. Redundancy enables playback in the event of failure of a drive in the array and also provides improved playback data retrieval time.

Claims

1. Apparatus for recording and playing a television data stream having video data and audio data comprising:

an array of non-continuous access, asynchronous disk drives for storing the video and audio data from the television data stream;

a cache having a circular structure and a capacity less than the array of asynchronous disk drives, but sufficient to minimize disk drive data requests during motion state changes, for either receiving the television data stream from an external device and storing said received television data stream temporarily until said television data stream can be transferred in discrete portions as video and audio data to said array of asynchronous disk drives while still storing the received television data stream, or retrieving discrete portions of video and audio data from said array of asynchronous disk drives and storing said retrieved video and audio data until said retrieved video and audio data is transferred as the television data stream to an external device while still storing the retrieved video and audio data; and

computer means for directing operation of said cache to provide interchange of video and audio data as the television data stream between said array of asynchronous disk drives and an external device.

2. Apparatus according to claim 1, wherein said cache comprises memory for holding said television data stream from an external device and for holding retrieved data from said array of non-continuous access, asynchronous disk drives.

3. Apparatus according to claim 1, for recording and playing video data, wherein said cache comprises a plurality of video data storage blocks, each equal in length to a predetermined multiple of frames of video data for storing video data from or for the television data stream.

4. Apparatus according to claim 1, for recording and playing video data and associated audio data, wherein said cache comprises a plurality of multiple frame video data storage blocks for storing video data and a plurality of corresponding audio data storage blocks for storing audio data from or for the television data stream.

5. Apparatus according to claim 1, wherein said computer means further comprises program means for managing organized exchange of data between an external device and said cache and between said cache and said array of non-continuous access, asynchronous disk drives.

6. Apparatus according to claim 1 further comprising a redundant disk drive for recording redundant data and enabling playback of valid data even when less than the entire array of non-continuous access, asynchronous disk drives has provided playback data.

7. A video disk recorder comprising:

an array of n non-continuous access, asynchronous disk drives for storing video and audio data from a television data stream, one of said asynchronous disk drives storing redundant data;

a memory cache having a circular structure and a lesser capacity than the disk drives, but sufficient to minimize disk drive data requests during motion state changes, for either receiving the television data stream from an external device and storing the received television data stream temporarily as video and audio data until the television data stream can be transferred in discrete portions to the array of asynchronous disk drives while still storing the received television data stream, or retrieving discrete portions of video and audio data from the array of asynchronous disk drives and storing the retrieved video and audio data until the retrieved video and audio data is transferred as the television stream to an external device while still storing the retrieved video and audio data; and

computer means for directing operation of said memory cache to provide interchange of video and audio data as the television data stream between the array of asynchronous disk drives and an external device.

8. Apparatus according to claim 7 wherein said computer means comprises means for retrieving video and audio data from the array of asynchronous disk drives after n−

1 of the disk drives have responded to a request for data retrieval.

9. A digital video recorder according to claim 7, wherein said memory cache is organized as a plurality of blocks, each equal in length to a predetermined multiple of frames of video data and a plurality of said memory cache blocks store video data.

10. A digital video recorder according to claim 7, for recording and playing both video data and audio data, wherein said memory cache is organized as a plurality of blocks, each equal in length to a predetermined multiple of frames of video data, and a first plurality of said memory cache blocks are adapted to store video data and a second corresponding plurality of said memory cache blocks are adapted to store audio data.

11. A method for recording and playing a television data stream having video and audio data comprising the steps of:

receiving the television data stream from an external device;

storing continuously the received television data stream as the video and audio data in a cache having a circular structure and a capacity sufficient to minimize data transfer requests during motion state changes;

transferring the video and audio data from the cache in discrete portions to an array of non-continuous access, asynchronous disk drives having a greater capacity than the cache while storing the received television data stream thereby recording the video and audio data;

receiving the video and audio data in discrete portions from the array of non-continuous access, asynchronous disk drives;

storing the received video and audio data in said cache; and

transferring continuously the video and audio data from the cache to the external device as the television data stream while storing the video and audio data thereby playing the data.