Rate control method with frame-layer bit allocation and video encoder
AssigneeMediatek Inc.
InventorsDo Kyoung Kwon, Meiyin Shen, Chung-Chieh Kuo
Life of this patent
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Abstract
A video encoder controlling rate of each frame in a current frame set (Group of Picture, GOP), and method thereof. The video encoder comprises a frame grouping device, a GOP initialization device, and a GOP encoding device. The frame grouping device allocates a target bit budget RGOP to the current frame set. The GOP initialization device is coupled to the frame grouping device, and estimates a first quantization parameter QP1 based on the target bit budget RGOP and complexity of the current frame set. The GOP encoding device is coupled to the GOP initialization device, and encoding a frame in the current frame set with the second quantization parameter QP2 to generate output data.
Claims28
A method of rate control with bit allocation to each frame in a current frame set, comprising:
- allocating a target number of bits to the current frame set;
- analyzing a frame in the current frame set by encoding with an average quantization parameter QPavg of a previous frame set to obtain a rate model and a distortion model of the frame;
- determining a first quantization parameter of the frame based on the target number of bits, the rate model and the distortion model using Lagrange optimization algorithm;
- and
- encoding the frame with the first quantization parameter to generate output data;
- wherein the allocating step comprises allocating the target number of bits RGOP based on the following expression:
- R
- GOP
- =
- C
- ·
- N
- GOP
- f
- +
- ɛ
- ,
- where NGOP is a total number of all frames in the current frame set;
- C is a channel rate;
- f is a frame rate;
- and
- ε is a feedback term from the previous frame set.
A method of rate control for each frame of a current frame set in a video encoder, comprising:
- allocating a target bit budget RGOP to the current frame set;
- estimating a first quantization parameter QP1 based on the target bit budget and complexity of the current frame set;
- and
- encoding a frame in the current frame set with the first quantization parameter to generate output data;
- and
- wherein the estimating step comprises estimating the first quantization parameter QP1 based on the following:
- R
- GOP
- =
- η
- ·
- S
- Qs
- ;
- where RGOP is the target bit budget;
- S is the complexity of the current frame set;
- η is a model parameter of the first quantization parameter;
- and
- Qs is the average quantization stepsize of the current frame set.
A video encoder, controlling rate of each frame in a current frame set (Group of Picture, GOP), comprising:
- a frame grouping device, allocating a target bit budget RGOP to the current frame set;
- a GOP initialization device coupled to the frame grouping device, estimating a first quantization parameter QP1 based on the target bit budget RGOP and complexity of the current frame set;
- and
- a GOP encoding device coupled to the GOP initialization device, encoding a frame in the current frame set with the first quantization parameter to generate output data;
- and
- wherein the GOP initialization device estimates the first quantization parameter QP1 based on the following
- R
- GOP
- =
- η
- ·
- S
- Qs
- ;
- where RGOP is the target bit budget;
- S is the complexity of the current frame set;
- η is a model parameter;
- and
- Qs is the average quantization stepsize of the current frame set.
Dependencies are inferred from the claim text.