Method for rate control for constant-bit-rate-finite-buffer-size video encoder

• US 9,414,078 B2
• Filed: 03/02/2007
• Issued: 08/09/2016
• Est. Priority Date: 04/18/2000
• Status: Active Grant

• Current Assignee: ATI Technologies ULC (Advanced Micro Devices, Inc.)
• Original Assignee: ATI Technologies ULC (Advanced Micro Devices, Inc.)
• Inventors: Eckart, Stefan
• Primary Examiner(s): LI, TRACY Y
• Application Number:
  US11/681,492
• Publication Number:
  US 20070147512A1
• Time in Patent Office: 3,448 Days
• Field of Search: 375/240.01, 375/240.07
• US Class Current: 1/1
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/12 Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/142 Detection of scene cut or scene change
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/177 the unit being a group of pictures [GOP]
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/33 in the spatial domain
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/65 using error resilience

Abstract

A method and apparatus for rate control for a constant-bit-rate finite-buffer-size video encoder is described. Rate control is provided by adjusting the size of non-intra frames based on the size of intra frames. A sliding window approach is implemented to avoid excessive adjustment of non-intra frames located near the end of a group of pictures. A measurement of “power” based on a sum of absolute values of pixel values is used. The “power” measurement is used to adjust a global complexity value, which is used to adjust the sizes of frames. The global complexity value responds to scene changes. An embodiment of the invention calculates and uses L1 distances and pixel block complexities to provide rate control. An embodiment of the invention implements a number of bit predictor block. Predictions may be performed at a group-of-pictures level, at a picture level, and at a pixel block level. An embodiment of the invention resets a global complexity parameter when a scene change occurs.

Claims

1. A method for rate control for a constant-bit-rate finite-buffer-size video encoder comprising:

calculating a group-of-pictures-level prediction for a number of bits encoded for a group of pictures;

calculating a picture-level prediction for a number of bits encoded for a picture;

calculating a pixel-block-level prediction for a number of bits encoded for a pixel block; and

using the group-of-pictures-level prediction, the picture-level prediction, and the pixel-block-level prediction to adjust a quantizer scale factor to provide the rate control for the video encoder.

2. The method of claim 1 wherein calculating the picture-level prediction for the number of bits encoded for the picture further comprises:

calculating the picture-level prediction for the number of bits encoded for the picture based on a pixel block type, a sum of absolute values of pixel-level error values, and a pixel block complexity.

3. The method of claim 1 wherein calculating the pixel-block-level prediction for the number of bits encoded for the pixel block further comprises:

calculating the pixel-block-level prediction for the number of bits encoded for the pixel block based on a local activity value.

4. The method of claim 1 wherein calculating the group-of-pictures-level prediction for the number of bits encoded for the group of pictures further comprises:

calculating the group-of-pictures-level prediction for the number of bits encoded for the group-of-pictures based on a global complexity value.