Encoder using coding tree unit level adaptive quantization mode to adjust frame level quantization parameter and associated signal processing method

Patent metadata

Field	Value
Publication number	US-11523117-B2
Application number	US-202117207771-A
Country	US
Kind code	B2
Filing date	Mar 22, 2021
Priority date	Mar 22, 2021
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

An encoder includes a frame level processing circuit, a coding tree unit (CTU) level processing circuit and an encoding circuit. The frame level processing circuit is arranged to calculate a bit number of a current frame according a target bitrate and a frame rate, and the frame level processing circuit is further arranged to calculate a quantization parameter of the current frame according to the bit number of the current frame and at least one parameter. The CTU level processing circuit is arranged to use an adaptive quantization mode to adjust the quantization parameter to generate an adjusted quantization parameter. The encoding circuit is arranged to encode the current frame to generate output data according to the adjusted quantization parameter.

First claim

What is claimed is:

1. An encoder, comprising:
a frame level processing circuit, arranged to calculate a bit number of a current frame according a frame rate and a target bitrate of the encoder, and calculate a quantization parameter of the current frame according to the bit number of the current frame and at least one parameter;
a coding tree unit (CTU) level processing circuit, coupled to the frame level processing circuit, and arranged to use an adaptive quantization mode to adjust the quantization parameter to generate an adjusted quantization parameter; and
an encoding circuit, coupled to the CTU level processing circuit, and arranged to encode the current frame to generate an output data according to the adjusted quantization parameter;
wherein if the current frame is an intra frame, the frame level processing circuit calculates a sum of intra costs of all blocks in the current frame, calculates a distributed bit number of the current frame according to the sum, the bit number of the current frame, and a first parameter, and calculates the quantization parameter according to the distributed bit number, the sum, the first parameter, and a second parameter; or
wherein if the current frame is a predicted frame, the frame level processing circuit calculates the quantization parameter according to the bit number of the current frame, the first parameter, and the second parameter.

2. The encoder of claim 1 , wherein the current frame comprises multiple blocks; for any block of the current frame, the CTU level processing circuit calculates a quantization parameter adjustment radix of the block of the current frame according to energy and a quantization parameter adjustment radix of a corresponding block of a previous frame and energy of the block, and adjusts the quantization parameter according to the quantization parameter adjustment radix of the block of the current frame, to obtain the adjusted quantization parameter corresponding to the block.

3. The encoder of claim 1 , wherein the frame level processing circuit updates the first parameter or the second parameter for use in calculating the quantization parameter of a next frame.

4. The encoder of claim 3 , wherein the frame level processing circuit or the CTU level processing circuit determines whether the next frame and the current frame involve scene change; if the next frame and the current frame involve scene change, the frame level processing circuit uses the first parameter and the second parameter to calculate the quantization parameter of the next frame; and if the next frame and the current frame do not involve scene change, the frame level processing circuit uses the first parameter after updating and the second parameter after updating to calculate the quantization parameter of the next frame.

5. A signal processing method applied in an encoder, comprising:
calculating a bit number of a current frame according to a frame rate and a target bitrate of the encoder;
calculating a quantization parameter of the current frame according to the bit number of the current frame and at least one parameter;
using an adaptive quantization mode to adjust the quantization parameter to generate an adjusted quantization parameter; and
according to the adjusted quantization parameter, encoding the current frame to generate an output data;
wherein if the current frame is an intra frame, calculating the quantization parameter of the current frame according to the bit number of the current frame and the at least one parameter comprises:
calculating a sum of intra costs of all blocks in the current frame;
calculating a distributed bit number of the current frame according to the sum, the bit number of the current frame, and a first parameter; and
calculating the quantization parameter according to the distributed bit number, the sum, the first parameter, and a second parameter; or

wherein if the current frame is a predicted frame, calculating the quantization parameter of the current frame according to the bit number of the current frame and the at least one parameter comprises:
calculating the quantization parameter according to the bit number of the current frame, the first parameter, and the second parameter.

6. The signal processing method of claim 5 , wherein the current frame comprises multiple blocks, and using the adaptive quantization mode to adjust the quantization parameter to generate the adjusted quantization parameter comprises:
for any block of the current frame:
calculating a quantization parameter adjustment radix of the block of the current frame according to energy and a quantization parameter adjustment radix of a corresponding block of a previous frame and energy of the block; and
adjusting the quantization parameter to obtain the adjusted quantization parameter corresponding to the block according to the quantization parameter adjustment radix of the block of the current flame.

7. The signal processing method of claim 5 , further comprising:
updating the first parameter and the second parameter for use in calculating the quantization parameter of a next frame.

8. The signal processing method of claim 7 , further comprising:
determining whether the next frame and the current frame involve scene change;
if the next frame and the current frame involve scene change, using the first parameter and the second parameter to calculate the quantization parameter of the next frame; and
if the next frame and the current frame do not involve scene change, using the first parameter after updating and the second parameter after updating to calculate the quantization parameter of the next frame.

Assignees

• Realtek Semiconductor Corp

Inventors

• Zeng Weimin
• Chai Chi-Wang
• Li Wei
• He Qingxi
• Chen Wujun
• Zhang Rong

Classifications

• H04N19/96

  Tree coding, e.g. quad-tree coding · CPC title

• H04N19/42 Primary

  characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation (H04N19/635 takes precedence) · CPC title

• H04N19/146

  Data rate or code amount at the encoder output · CPC title

• H04N19/142

  Detection of scene cut or scene change · CPC title

• H04N19/124 Primary

  Quantisation · CPC title