Picture-level QP rate control performance improvements for HEVC encoding

• US 10,165,272 B2
• Filed: 01/29/2016
• Issued: 12/25/2018
• 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:
  US15/011,410
• Publication Number:
  US 20160227219A1
• Time in Patent Office: 1,061 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 are provided for controlling a bit rate of an encoded video that includes a plurality of pictures. In the method, each of the plurality of pictures is one of a plurality of picture types. For the method, the 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_cur needed to encode a current picture of picture type T according to;

2. The method of claim 1, further comprising:

after coding the current picture according to Q_curr;

updating α

_T and β

_T for the picture type T of the current picture;

setting a next remaining picture as the current picture and performing steps (c)-(g).

3. The method of claim 1, further comprising:

determining if a scene change has occurred in the current picture or any remaining picture i of the window of M pictures;

if a scene change has occurred in the current picture of any remaining picture of i of the window of M pictures;

resetting α

_T to an initial value α

_Tinitial for each picture types T for all pictures following the scene change in the window of M pictures; and

resetting β

_T to an initial value β

_Tinitial for each picture type T for all pictures following the scene change in the window of M pictures.

4. The method of claim 3, wherein:

the initial value β

_Tinitial is determined according to a mapping of statistics of the values of β

_T for picture types T of other pictures in the window of pictures; and

the initial value β

_Tinitial is determined according to a mapping of statistics of the values of β

_T for picture types T of other pictures in the window of pictures.

5. The method of claim 3, wherein:

the mapping of statistics of the values of β

_T for picture types T of other pictures in the window of pictures comprises the function α

=ƒ

(SAD);

the mapping of statistics of the values of β

_T for picture types T of other pictures in the window of pictures comprises the function β

=g(SAD); and

wherein SAD comprises a sum of an absolute difference between the current picture and the other pictures in the window.

6. The method of claim 1, further comprising:

determining if a number of intra coding units in the current picture or any remaining picture i of the window of M pictures comprises more than a percentage of the picture;

if the number of intra coding units in the current picture or any remaining picture i of the window of M pictures comprises more than a percentage of the picture;

resetting α

_T to an initial value α

_Tinitial; and

resetting β

_T to an initial value β

_Tinitial for each picture type T for all pictures following a scene change in the window of M pictures.

7. The method of claim 1, wherein the determination if a maximum video buffer boundary B_upper or a minimum video buffer boundary B_low are exceeded is further determined from a predicted number of bits of the previously coded picture.

8. The method according to claim 1, wherein determining if a statistic of the current picture differs from a statistic of one or more adjacent pictures by greater than a threshold value comprises:

determining if a sum of absolute difference value of the current picture is different than an average value of a sum of absolute difference value of the one or more adjacent pictures exceeds a threshold value.

9. The method of claim 8, wherein:

estimating the number of bits R needed to encode the current picture type T according to

10. The method of claim 1, further comprising:

after coding the current picture, setting a next remaining picture as the current picture without updating α

_T and β

_T for the picture type T of the current picture; and

performing steps (c)-(g).

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 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. The apparatus of claim 11, wherein the instructions further comprise instructions for:

after coding the current picture according to Q_curr;

updating α

_T and β

_T for the picture type T of the current picture;

setting a next remaining picture as the current picture and performing instructions (c)-(g).

13. The apparatus of claim 11, wherein the instructions further comprise:

determining if a scene change has occurred in the current picture or any remaining picture i of the window of M pictures;

if a scene change has occurred in the current picture of any remaining picture of i of the window of M pictures;

resetting α

_T to an initial value α

_Tinitial for each picture types T for all pictures following the scene change in the window of M pictures; and

resetting β

_T to an initial value B_Tinitial for each picture type T for all pictures following the scene change in the window of M pictures.

14. The apparatus of claim 13, wherein:

the initial value α

_Tinitial is determined is determined according to a mapping of statistics of the values of α

_T for picture types T of other pictures in the window of pictures; and

the initial value β

_Tinitial is determined according to a mapping of statistics of the values of β

_T for picture types T of other pictures in the window of pictures.

15. The apparatus of claim 13, wherein:

the mapping of statistics of the values of α

_T for picture types T of other pictures in the window of pictures comprises the function α

=ƒ

(SAD);

the mapping of statistics of the values of β

_T for picture types T of other pictures in the window of pictures comprises the function β

=g(SAD); and

wherein SAD is a sum of an absolute difference between the current picture and the other pictures in the window.

16. The apparatus of claim 11, wherein the instructions further comprise instructions for:

determining if a number of intra coding units in the current picture or any remaining picture i of the window of M pictures comprises more than a percentage of the picture;

if the number of intra coding units in the current picture or any remaining picture i of the window of M pictures comprises more than a percentage of the picture;

resetting α

_T to an initial value α

_Tinitial; and

resetting β

_T to an initial value β

_Tinitial for each picture type T for all pictures following a scene change in the window of M pictures.

17. The apparatus of claim 11, wherein the determination if a maximum video buffer boundary B_upper or a minimum video buffer boundary B_low are exceeded is further determined from a predicted number of bits of the previously coded picture.

18. The apparatus according to claim 11, wherein the instruction for determining if a statistic of the current picture differs from a statistic of one or more adjacent pictures by greater than a threshold value comprise instructions for:

determining if a sum of absolute difference value of the current picture is different than an average value of a sum of absolute difference value of the one or more adjacent pictures exceeds a threshold value.