EFFICIENT QUANTIZATION PARAMETER PREDICTION METHOD FOR LOW LATENCY VIDEO CODING

• US 20200137390A1
• Filed: 10/31/2018
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: ATI Technologies ULC (Advanced Micro Devices, Inc.)
• Original Assignee: ATI Technologies ULC (Advanced Micro Devices, Inc.)
• Inventors: Lew, Dennis, Wang, Jiao, Zhang, Lei, Harold, Edward A.
• Granted Patent: US 10,924,739 B2
• Time in Patent Office: Days
• 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 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• 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

Abstract

Systems, apparatuses, and methods for calculating a quantization parameter (QP) for encoding video frames to meet a given bit budget are disclosed. Control logic coupled to an encoder calculates a complexity indicator that represents a level of difficulty in encoding a previous video frame. The complexity indicator is based at least in part on a first parameter associated with the previous video frame and corresponds to one or more of a variance, an intra-prediction factor, and an inter-to-intra ratio. The complexity indicator is then used by the control logic to calculate a preferred QP to use to encode the current video frame to meet a given bit budget. By using the preferred QP generated based on the complexity indicator, the encoder is able to make fewer QP adjustments during the frame. This helps to improve the visual quality of the resulting encoded video bitstream.

Claims

1. A system comprising:

an encoder configured to encode video frames of a video stream;

control logic coupled to the encoder, wherein the control logic is configured to;

calculate a complexity indicator that represents a level of difficulty in encoding a previous video frame; and

calculate a quantization parameter (QP) value based on the complexity indicator and a preferred size of an encoded video frame;

wherein the encoder is configured to;

generate an encoded video frame that represents a current video frame by setting a QP to the QP value calculated by the control logic; and

convey the encoded video frame to a decoder to be displayed.

2. The system as recited in claim 1, wherein the complexity indicator is based at least in part on a first parameter associated with the previous video frame and corresponds to one or more of a variance, an intra-prediction factor, and an inter-to-intra ratio.

3. The system as recited in claim 2, wherein the intra-prediction factor represents how effective intra prediction was for the previous video frame at a given QP.

4. The system as recited in claim 2, wherein the inter-to-intra ratio represents a ratio of inter-coded bits to intra-coded bits for the previous video frame at a given QP.

5. The system as recited in claim 1, wherein the control logic is further configured to calculate the complexity indicator based on two or more previous video frames of the video stream.

6. The system as recited in claim 1, wherein the preferred size of the encoded video frame is calculated based on a preferred bit rate of an encoded video bitstream.

7. The system as recited in claim 1, wherein the control logic is further configured to generate one or more parameters based on the current video frame for use in generating a next complexity indicator for encoding a next video frame.

8. A method comprising:

calculating, by control logic, a complexity indicator based on a level of difficulty in encoding a previous video frame;

calculating, by the control logic, a quantization parameter (QP) value based on the complexity indicator and a preferred size of an encoded video frame;

generating, by an encoder, an encoded video frame that represents a current video frame by setting a QP to the QP value calculated by the control logic; and

conveying, by the encoder, the encoded video frame to a decoder to be displayed.

9. The method as recited in claim 8, wherein the complexity indicator is based at least in part on a first parameter associated with the previous video frame and corresponds to one or more of a variance, an intra-prediction factor, and an inter-to-intra ratio.

10. The method as recited in claim 9, wherein the intra-prediction factor represents how effective intra prediction was for the previous video frame at a given QP.

11. The method as recited in claim 9, wherein the inter-to-intra ratio represents a ratio of inter-coded bits to intra-coded bits for the previous video frame at a given QP.

12. The method as recited in claim 8, further comprising calculating the complexity indicator based on two or more previous video frames of the video stream.

13. The method as recited in claim 8, wherein the preferred size of the encoded video frame is calculated based on a preferred bit rate of an encoded video bitstream.

14. The method as recited in claim 8, further comprising generating one or more parameters based on the current video frame for use in generating a next complexity indicator for encoding a next video frame.

15. An apparatus comprising:

a memory;

an encoder coupled to the memory; and

control logic coupled to the encoder, wherein the control logic is configured to;

calculate a complexity indicator based on a level of difficulty in encoding a previous video frame; and

calculate a quantization parameter (QP) value based on the complexity indicator and based on a preferred size of an encoded video frame;

wherein the encoder is configured to;

generate an encoded video frame that represents a current video frame by setting a QP to the QP value calculated by the control logic; and

convey the encoded video frame to a decoder to be displayed.

16. The apparatus as recited in claim 15, wherein the complexity indicator is based at least in part on a first parameter associated with the previous video frame and corresponds to one or more of a variance, an intra-prediction factor, and an inter-to-intra ratio.

17. The apparatus as recited in claim 16, wherein the intra-prediction factor represents how effective intra prediction was for the previous video frame at a given QP.

18. The apparatus as recited in claim 16, wherein the inter-to-intra ratio represents a ratio of inter-coded bits to intra-coded bits for the previous video frame at a given QP.

19. The apparatus as recited in claim 15, wherein the control logic is configured to calculate the complexity indicator based on two or more previous video frames of the video stream.

20. The apparatus as recited in claim 15, wherein the preferred size of the encoded video frame is calculated based on a preferred bit rate of an encoded video bitstream.