Picture-level QP rate control for HEVC encoding

• US 10,171,807 B2
• Filed: 01/29/2016
• Issued: 01/01/2019
• Est. Priority Date: 01/29/2015
• Status: Expired due to Fees

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Inventors: Wang, Limin, Hong, Seungwook
• Primary Examiner(s): Philippe, Gims S
• Assistant Examiner(s): Gadomski, Stefan
• Application Number:
  US15/011,394
• Publication Number:
  US 20160227212A1
• Time in Patent Office: 1,068 Days
• Field of Search: 37524003
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• 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 19/179 the unit being a scene or a shot
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques

Abstract

A method and system for controlling a bit rate of an encoded video including a plurality of pictures is provided. In the method, each of the plurality of pictures is one of a plurality of picture types. For the method, a number of bits required to encode a current picture as well as other pictures in a window is determined, and the fullness of a buffer storing the current picture and other picture data is estimated and compared to buffer fullness limits. This process is repeated for different quantization values to determine a suitable quantization value.

Claims

1. A method of controlling a bit rate of an encoded video comprising a plurality of pictures, each of the plurality of pictures being of one of a plurality of picture types, comprising:

(a) defining a window of M pictures comprising a plurality of window pictures;

(b) defining a parameter set for each picture type T, each parameter set comprising;

a quantization parameter (Q_T);

a first parameter (α

_T);

a second parameter (β

_T);

(c) estimating a number of bits R needed to encode a current picture of picture type T;

according to;

2. The method of claim 1, further comprising:

repeating (d)-(g) for further adjusted values for the current picture of picture type T and Q_iT of each remaining picture i of picture type T;

choosing an optimal Q_iT from among the adjusted and further adjusted values; and

coding the current picture according to the optimal Q_iT.

4. The method of claim 1, wherein determining, for the current picture and each remaining picture i of the window of M pictures and from the estimated number of bits to needed to encode the current picture R_cur and the estimated number of bits needed encode each remaining picture i of the window of M pictures, if a maximum video buffer boundary B_upper or a minimum video buffer boundary B_low are exceeded comprises:

determining an estimated video buffer fullness immediately before the coding of the current picture as B_cur−

=B<sub>(cur−

1)+</sub>+R_{pic nominal}<

B_upper, wherein B<sub>(cur−

2)+</sub> is the video buffer fullness just after the picture temporally previous to the current picture, and R_{pic nominal} is a nominal number of bits per picture;

determining an estimated video buffer fullness immediately after the coding of the current picture as B_cur+=B_cur−

−

R_cur<

B_low;

determining an estimated video buffer fullness immediately before the coding of each picture i as B_i−

=B<sub>(i−

1)+</sub>+R_{pic nominal}<

B_upper, wherein B<sub>(i−

2)+</sub> is the video buffer fullness just after the temporally previous picture;

determining an estimated video buffer fullness immediately after the coding of picture i as B₁₊=B_i−

−

R_i<

B_low;

determining that a maximum video buffer boundary B_upper or a minimum video buffer boundary B_low are exceeded only if;

B_cur−

−

B_upper;

B_cur+<

B_low;

B_i−

<

B_upper;

or

B_i+<

B_low.

5. The method of claim 1, wherein the quantization parameter Q_T for each picture type T differs from a quantization parameter for other picture types by an offset.

6. The method of claim 1, wherein the quantization parameter Q_T for each picture type T has the same value.

7. The method of claim 1, wherein defining a parameter set for each picture type T comprises:

setting α

_T to an initial value α

_Tinitial;

setting β

_T to an initial value β

_Tinitial; and

setting Q_T equal to an initial value Q_Tinitial.

8. The method of claim 1, wherein:

Q_curT has the value of Q_T for a most previously coded picture of the same type T as the current picture.

9. The method of claim 1, wherein:

α

_curT has the value of α

_T for a most previously coded picture of the same type T as the current picture;

β

_curT has a value of a β

_T value for a most previously coded picture of the same type T as the current picture;

α

_iT has the value of α

_T for a most previously coded picture of the same type T as the picture i; and

β

_curT has a value of a β

_T value for a most previously coded picture of the same type T as the picture i.

10. The method of claim 9, wherein:

the values of α

_curT and β

_curT are stored in a different memory than the values of α

_iT and β

_iT for each remaining picture; and

the values of α

_iT and β

_iT for each remaining picture i are stored in a different memory other values of α

_iT and β

_iT for the other remaining pictures.

3. A method of controlling a bit rate of an encoded video comprising a plurality of pictures, each of the plurality of pictures being of one of a plurality of picture types, comprising:

(a) defining a window of M pictures comprising a plurality of window pictures;

(b) defining a parameter set for each picture type T, each parameter set comprising;

a quantization parameter (Q_T);

a first parameter (α

_T);

a second parameter (β

_T);

(c) estimating a number of bits R needed to encode a current picture of picture type T;

according to;

11. An apparatus for controlling a bit rate of an encoded video comprising a plurality of pictures, each of the plurality of pictures being of one of a plurality of picture types, comprising:

a processor;

a memory, communicatively coupled to the processor, the memory storing instructions comprising instructions for;

(a) defining a window of M pictures comprising a plurality of window pictures;

(b) defining a parameter set for each picture type T, each parameter set comprising;

a quantization parameter (Q_T);

a first parameter (α

_T);

a second parameter (β

_T);

(c) estimating a number of bits R needed to encode a current picture of picture type T according to;

12. An apparatus for controlling a bit rate of an encoded video comprising a plurality of pictures, each of the plurality of pictures being of one of a plurality of picture types, comprising:

a processor;

a memory, communicatively coupled to the processor, the memory storing instructions comprising instructions for;

(a) defining a window of M pictures comprising a plurality of window pictures;

(b) defining a parameter set for each picture type T, each parameter set comprising;

a quantization parameter (Q_T);

a first parameter (α

_T);

a second parameter (β

_T);

(c) estimating a number of bits R needed to encode a current picture of picture type T according to;