Scalable rate control system for a video encoder
A rate control system for a video encoder including rate control logic which determines a first QP corresponding to a selected encoding layer of multiple encoding layers, and scaling logic configured to scale the first QP to a second QP corresponding to any other encoding layer based on at least one encoding layer parameter. A template of stored QP values may be used to reduce computational complexity, such as a QP value for each frame interval or a QP value for each of multiple rate control interval complexity values. The QP values in the template may be predetermined or programmed and updated during periodic training sessions. Several encoding layer parameters are contemplated, such as any combination of bit rate, frame rate and frame resolution. The scaling logic may be configured to scale from any one encoding layer to another and vice-versa for bi-directional scaling.
1. A rate control system for a video encoder, comprising:
a template comprising a plurality of predetermined and pre-stored quantization parameter (QP) values corresponding to a selected one of a plurality of encoding layers, wherein said template stores a plurality of QP values including at least one QP value for each of a set of motion complexity values each indicative of relative motion in which said plurality of motion complexity values range from low motion to high motion;
rate control logic which determines a new motion complexity value for each new rate control interval and which uses said new motion complexity value as an index to retrieves a first QP value from said template; and
scaling logic configured to scale said first QP value corresponding to said selected encoding layer to a second QP value corresponding to any other one of said plurality of encoding layers based on at least one encoding layer parameter.
2. The rate control system of claim 1 , wherein said rate control logic periodically performs a training session for calculating and storing a QP value for each interval of a selected video frame, and wherein said rate control logic retrieves a corresponding stored QP value for each interval of at least one subsequent video frame.
3. The rate control system of claim 1 , wherein said template stores at least one QP value for each of a plurality of rate control interval complexity values.
4. The rate control system of claim 3 , wherein said plurality of rate control interval complexity values comprises a plurality of mean of sum of absolute difference values.
5. The rate control system of claim 3 , wherein said template stores a plurality of QP values for each of said plurality of rate control interval complexity values, wherein each of said plurality of QP values further corresponds to one of a plurality of target bits per pixel parameters.
6. The rate control system of claim 1 , wherein each of said plurality of encoding layers is based on a plurality of encoding layer parameters, including a corresponding bit rate, a corresponding temporal resolution, and a corresponding spatial resolution.
7. The rate control system of claim 6 , wherein said scaling logic is configured to convert said first QP value to said second QP value by converting between a plurality of different bit rates, a plurality of different temporal resolutions, and a plurality of different spatial resolutions.
8. The rate control system of claim 7 , wherein said scaling logic converts said first QP value to said second QP value by adding a QP offset, and wherein said QP offset is determined based on any selected ones of a ratio of first and second bit rates, a ratio of first and second video frame rates, and a ratio of first and second video frame resolutions.
9. The rate control system of claim 1 , wherein said scaling logic is configured to scale from any one of said plurality of encoding layers to any other one of said plurality of encoding layers and vice-versa.
10. A scalable video encoding system, comprising:
a video encoder which encodes video information based on a quantization parameter (QP);
system control logic which provides at least one target encoding layer parameter indicating a corresponding one of a plurality of encoding layers; and
a rate control system which determines said QP corresponding to a selected one of said plurality of encoding layers, comprising:
a template which stores a plurality of predetermined and pre-stored QP values corresponding to said selected one of said plurality of encoding layers, wherein said template stores a plurality of QP values including at least one QP value for each of a set of motion complexity values each indicative of relative motion in which said plurality of motion complexity values range from low motion to high motion;
rate control logic which calculates a new complexity value for each new rate control interval and which uses said new complexity value to retrieve a corresponding QP value from said template; and
scaling logic which is configured to scale said QP value retrieved from said template to correspond to any other one of said plurality of encoding layers based on said at least one target encoding layer parameter.
11. The scalable video encoding system of claim 10 , wherein each of said plurality of encoding layers is based on a selected bit rate, a selected temporal resolution, and a selected spatial resolution of said video information.
12. The scalable video encoding system of claim 11 , wherein said rate control system is configured to scale said QP value based on a plurality of different bit rates, a plurality of different temporal resolutions, and a plurality of different spatial resolutions.
13. The scalable video encoding system of claim 12 , wherein said rate control system is configured to add a QP offset to said QP value, and wherein said QP offset is determined based on any selected ones of a ratio of first and second bit rates, a ratio of first and second video frame rates, and a ratio of first and second video frame resolutions.
14. The scalable video encoding system of claim 10 , wherein said rate control system conducts a training session to program said template with a QP value for each rate control interval of a selected video frame.
15. The scalable video encoding system of claim 10 , wherein each of said plurality of QP values stored in said template corresponds to one of a plurality of frame complexity values.
16. The scalable video encoding system of claim 15 , wherein said video encoder provides a frame complexity value and pixel encoding information after encoding each interval of a video frame, and wherein said rate control system updates said template based on said frame complexity value and said pixel encoding information.
17. A method of scaling a quantization parameter (QP) for video encoding, comprising:
determining a first QP corresponding to a selected one of a plurality of encoding layers comprising retrieving a QP value from a template of predetermined and pre-stored QP values, wherein the template stores a plurality of QP values including at least one QP value for each of a set of motion complexity values each indicative of relative motion in which said plurality of motion complexity values range from low motion to high motion;
receiving a plurality of encoding parameters indicating a second one of the plurality of encoding layers; and
scaling the first QP to a second QP which corresponds with the second one of the plurality of encoding layers.
18. The method of claim 17 , wherein said receiving a plurality of encoding parameters comprises receiving a target bit rate, a target frame rate, and a target frame resolution.
19. The method of claim 17 , wherein said scaling the first QP to a second QP comprises adding a QP offset based on a change of at least one of bit rate, frame rate and frame resolution.