Method and apparatus for performing compression of image data

Patent metadata

Field	Value
Publication number	US-10230959-B2
Application number	US-201214401151-A
Country	US
Kind code	B2
Filing date	Jun 1, 2012
Priority date	Jun 1, 2012
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

A method of performing compression of image data for at least one image is described. The method comprises receiving image data of at least a part of the at least one image, encoding the received image data into at least one compressed data block, applying at least one bandwidth limit to the at least one compressed data block, and outputting the at least one bandwidth limited compressed data block to a buffer. The method further comprises dynamically updating the at least one bandwidth limit applied to the at least one compressed data block base at least partly on a fill level of the buffer.

First claim

The invention claimed is:

1. A method of performing compression of image data for a current image of a video data stream, the method comprising:
receiving image data of at least part of the current image;
encoding the received image data into at least one compressed data block in accordance with a compression factor;
applying at least one bandwidth limit to the at least one compressed data block by truncating bits from the at least one compressed data block; and
outputting the at least one bandwidth limited compressed data block to a buffer,

wherein the method further comprises dynamically updating the at least one bandwidth limit applied to the at least one compressed data block based at least partly on a fill level of the buffer and starting from an initial bandwidth limit for the current image, and determining the compression factor for encoding the received image data of the current image into the at least one compressed data block based at least partly on a data rate and a distribution of truncated bits for N previous images in the video data stream.

2. The method of claim 1 , wherein dynamically updating the at least one bandwidth limit is further based at least partly on at least one from a group comprising:
(i) a size of the buffer to which the at least one bandwidth limited compressed data block is output;
(ii) an egress rate of the buffer to which the at least one bandwidth limited compressed data block is output;
(iii) the initial bandwidth limit;
(iv) the data rate distribution of compressed image data for N previous images, where N equals an integer value; and
(v) the distribution of truncated bits for N previous images.

3. The method of claim 1 , wherein the method comprises dynamically reducing the at least one bandwidth limit upon the fill level of the buffer exceeding at least one threshold level.

4. The method of claim 3 , wherein the method comprises dynamically reducing the at least one bandwidth limit relative to the initial bandwidth limit by an amount dependent at least partly on by how much the fill level of the buffer exceeds the at least one threshold level.

5. The method of claim 3 , wherein the method comprises configuring the at least one threshold level based at least partly on at least one from a group consisting of:
(i) a size of the buffer to which the at least one bandwidth limited compressed data block is output;
(ii) an egress rate of the buffer to which the at least one bandwidth limited compressed data block is output; and
(iii) the initial bandwidth limit.

6. The method of claim 1 , wherein the method comprises calculating the initial bandwidth limit to be applied to compressed data blocks for the current image based at least partly on a data rate for at least one previous image.

7. The method of claim 6 , wherein the method comprises calculating the initial bandwidth limit for the current image based at least partly on at least one from a group consisting of:
(i) a data rate distribution of compressed image data for N previous images, where N equals an integer value;
(ii) a distribution of truncated bits for N previous images; and
(iii) the compression factor for N previous images.

8. The method of claim 7 , wherein the method comprises performing low pass filtering of distribution data for the N previous images used for calculating the initial bandwidth limit.

9. The method of claim 1 , wherein the method comprises applying separate bandwidth limits to different image components of the at least one compressed data block.

10. The method of claim 9 , wherein the method comprises applying separate bandwidth limits to luma and chroma components of the at least one compressed data block.

11. A method of performing compression of image data for a current image of a video data stream, the method comprising:
receiving image data of at least part of the current image;
encoding the received image data into at least one compressed data block in accordance with a compression factor;
applying at least one bandwidth limit to the at least one compressed data block by truncating bits from the at least one compressed data block; and
outputting the at least one bandwidth limited compressed data block to a buffer,

wherein the method further comprises dynamically updating the at least one bandwidth limit by calculating the compression factor for encoding the received image data of the current image into compressed data blocks based at least partly on a data rate and a distribution of truncated bits for each of a plurality of images in the video data stream prior to the current image in the video data stream.

12. The method of claim 11 , wherein calculating the compression factor for encoding received image data of the current image into compressed data blocks based at least partly on at least one from a group consisting of:
(i) a data rate distribution of compressed image data for N previous images, where N equals an integer value; and
(ii) the compression factor for N previous images.

13. The method of claim 12 , wherein the method comprises performing low pass filtering of distribution data for N previous images used for calculating the compression factor for encoding received image data of the current image into compressed data blocks.

14. The method of claim 11 , wherein calculating the compression factor for encoding the received image data of the current image is further based on at least one from a group consisting of:
(i) a size of the buffer to which the at least one bandwidth limited compressed data block is output; and
(ii) an egress rate of the buffer to which the at least one bandwidth limited compressed data block is output.

15. The method of claim 11 , wherein the method for use in a latency sensitive video application.

16. An encoder module comprising:
an encoding component arranged to receive image data of at least part of a current image of a video data stream, and to encode the received image data into at least one compressed data block in accordance with a compression factor; and
a bandwidth limiter component arranged to apply at least one bandwidth limit to the at least one compressed data block, and to output the at least one bandwidth limited compressed data block to a buffer,
wherein the encoder module further comprises a controller component arranged to dynamically update the at least one bandwidth limit applied to the at least one compressed data block based at least partly on a fill level of the buffer and starting from an initial bandwidth limit for the current image, and calculate the compression factor for encoding received image data of the current image into compressed data blocks based at least partly on a data rate and a distribution of truncated bits for each of a plurality of images in the video data stream prior to the current image in the video data stream.

Assignees

• Singer Stefan
• Gerster Jochen
• Herrmann Stephan
• Neff Albrecht
• Nxp Usa Inc

Inventors

• Singer Stefan
• Gerster Jochen
• Herrmann Stephan
• Neff Albrecht

Classifications

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/152 Primary

  by measuring the fullness of the transmission buffer · CPC title

• H04N19/172

  the region being a picture, frame or field · CPC title

• H04N19/115

  Selection of the code volume for a coding unit prior to coding · CPC title