Video encoder for digital video displays

• US 6,507,672 B1
• Filed: 09/30/1997
• Issued: 01/14/2003
• Est. Priority Date: 09/10/1997
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Dierke, Gregg, Watkins, Daniel
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Alavi, Amir
• Application Number:
  US08/940,784
• Time in Patent Office: 1,932 Days
• Field of Search: 382/232-233, 382/236, 382/238, 382/107, 382/209, 382/239, 375/240.01, 375/240.12, 375/240.13, 375/240.25, 375/240.27, 375/240.16, 375/240.17, 375/240.26, 375/240.02, 348/207, 348/231, 348/232, 348/409, 348/416, 386/33, 386/109, 386/111, 386/112, 386/116, 386/124
• US Class Current: 382/232
• CPC Class Codes: H04N 21/4384 involving operations to reduce the access time, e.g. fast-tuning for reducing channel switching latency

Abstract

An improved multimedia encoder having features advantageous for use in a computer system. These features provide for the reduction of bandwidth and storage requirements, the enhancement of noise immunity, the evening of computational loading, and the use of multimedia drives for general purpose data storage. In one embodiment, the encoder receives image data representing a sequence of video frames and display text data representing a sequence of text fields to be overlaid on the sequence of video frames. The multimedia encoder produces a compressed video frame only for each subsequent video frame which is different from the current video frame. After each video frame is compressed, it becomes the current frame. The multimedia encoder provides error correction encoding to enhance noise immunity, and performs interframe compression using a dynamic search area to even out computational loading. Additionally, the multimedia encoder allows text file storage using a sub-picture unit bitstream and direct binary file storage, thereby enabling a write-able multimedia disk to displace a hard disk drive. A companion multimedia decoder recognizes these features and decodes a multimedia bitstream accordingly.

Claims

1. An improved multimedia encoder for compressing digital video displays, wherein the encoder comprises:

a video buffer configured to receive image data;

a microprocessor coupled to the video buffer to retrieve image data and configured to store a previous video frame in a frame store, wherein the microprocessor is further configured to generate a compressed multimedia bitstream which includes a compressed video bitstream representative of the received image data; and

a bitstream buffer coupled to the microprocessor to receive the compressed multimedia bitstream;

wherein the previous video frame is one of a sequence of video frames which includes a subsequent video frame, and wherein a compressed representation of the subsequent video frame is provided to the bitstream buffer as part of the multimedia bitstream only if the subsequent video frame is different from the previous video frame, wherein the compressed video bitstream includes a compressed representation of the subsequent video frame which is compressed using the previous video frame as a reference, wherein the microprocessor is configured to search a dynamically-sized area of the previous video frame for a previous image block which most closely matches a subsequent image block, and wherein the microprocessor increases the search area size during periods of low processor usage and decreases the search area size during periods of high processor usage.

2. The improved multimedia encoder of claim 1, wherein the microprocessor is further configured to receive text data and configured to store a previous text field in a text field store, wherein when the text data represents a change to the previous text field, the microprocessor is configured to provide a compressed representation of a subsequent text field to the bitstream buffer as part of the multimedia bitstream.

3. The improved multimedia encoder of claim 2, wherein the text data represents user edits to the previous text field.

4. The improved multimedia encoder of claim 1, wherein the image data is said sequence of video frames.

5. The improved multimedia encoder of claim 1, wherein the image data is a sequence of deltas representing subsequent video frames by changes to previous video frames.

6. The improved multimedia encoder of claim 1, wherein the compressed video bitstream is coded by the microprocessor to provide redundancy to enhance noise immunity.

7. An improved multimedia encoder with regulated computational loading, wherein the encoder comprises:

a video buffer configured to receive image data;

a microprocessor coupled to the video buffer to retrieve image data and configured to store a previous video frame in a frame store, wherein the microprocessor is further configured to generate a compressed multimedia bitstream which includes a compressed video bitstream representative of the received image data; and

a bitstream buffer coupled to the microprocessor to receive the compressed multimedia bitstream;

wherein the previous video frame is one of a sequence of video frames which includes a subsequent video frame, wherein microprocessor compresses the subsequent video frame using the previous video frame as a reference, wherein the microprocessor is configured to search a dynamically-sized area of the previous video frame for a previous image block which most closely matches a subsequent image block, and wherein the microprocessor increases the search area size during periods of low processor usage and decreases the search area size during periods of high processor usage.

8. An improved multimedia encoder with a dynamic search area, wherein the encoder comprises:

a video buffer configured to receive image data;

a microprocessor coupled to the video buffer to retrieve image data and configured to store a previous video frame in a frame store, wherein the microprocessor is further configured to generate a compressed multimedia bitstream which includes a compressed video bitstream representative of the received image data; and

a bitstream buffer coupled to the microprocessor to receive the compressed multimedia bitstream;

wherein the previous video frame is one of a sequence of video frames which includes a subsequent video frame, wherein microprocessor compresses the subsequent video frame using the previous video frame as a reference, wherein the microprocessor is configured to search the previous video frame for a first previous image block which matches a subsequent image block to within an adjustable threshold, and wherein the microprocessor is configured to terminate the search upon finding said first previous image block.