Video encoding apparatus and method

• US 7,023,914 B2
• Filed: 01/26/2001
• Issued: 04/04/2006
• Est. Priority Date: 02/29/2000
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kikuchi, Yoshihiro, Furukawa, Rieko
• Primary Examiner(s): RAO, ANAND SHASHIKANT
• Application Number:
  US09/769,309
• Publication Number:
  US 20010017887A1
• Time in Patent Office: 1,894 Days
• Field of Search: 37524002-24008
• US Class Current: 375/240.02
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• 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 19/15 by monitoring actual compressed data size at the memory before deciding storage at 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 19/192 the adaptation method, adaptation tool or adaptation type being iterative or recursive
• CPC Class Codes: H04N 19/194 involving only two passes
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A video encoding apparatus comprising a feature amount computation section which divides an input video signal into a plurality of scenes each comprising at least one temporally-continuous frame, and compute a statistical feature amount for each scene, an encoding parameter generator section which generates an encoding parameter for each scene based on the statistical feature amount, a number-of-generated-bits prediction section which predicts the number of bits to be generated when the input video signal is encoded using the encoding parameter, an encoding parameter correcting section which corrects the encoding parameter based on a result of the prediction of the number of generated bits, an encoder section which encodes the input video signal using the corrected encoding parameter.

Claims

1. A video encoding apparatus comprising:

a feature amount computation unit configured to divide an input video signal into a plurality of scenes each comprising at least one temporally-continuous frame, and compute a statistical feature amount for each scene;

an encoding parameter generator to generate an encoding parameter for each scene based on the statistical feature amount computed by the feature amount computation unit;

a number-of-generated-bits prediction unit configured to predict the number of bits to be generated when the input video signal is encoded using the encoding parameter generated by the encoding parameter generator;

an encoding parameter correcting unit configured to correct the encoding parameter based on a result of the prediction of the number of generated bits which is obtained by the number-of-generated-bits prediction unit;

an encoder to encode the input video signal using the corrected encoding parameter and generate an encoded bit stream; and

an output unit configured to output the encoded bit stream generated by the encoder as an encoded output, wherein the encoding parameter generator includes a setting unit configured to correct a frame rate as well as a quantization step by setting a weighted parameter to the frame rate as well as setting a weighted parameter to the quantization step size for macro blocks of frames to be encoded for each scene on the bases of the statistical feature amount relating to a distribution of luminance for each macro block.

8. The apparatus according to claim 1, wherein the setting unit includes a computing unit configured to compute the frame rate and the quantization step from a sum of a value determined by a bit rate, a video size and a representative value for each scene and a value determined by a motion vector of an object in the scene.

9. The apparatus according to claim 1, wherein the setting unit includes a computing unit configured to compute the frame rate and the quantization step by a following equation:

FR(j)=a*MVnum_—

j+b+W_—

FR

where FR(j) represents the frame rate, MVnum_j denotes a representative value for a j-th scene, a and b denote coefficients for a bit rate and a video size specified by a user, and W_FR denotes a weight parameter, and

QP(j)=c*MVnum_—

j+d+W_—

QP

where QP(j) represents the frame rate, c and d denote coefficients for a bit rate and a video size specified by a user, and W_QP denotes a weight parameter.

10. The apparatus according to claim 1, wherein the setting unit includes a reset unit configured to reset the bit rate exceeding an upper limit value or a lower limit value.

2. A video encoding apparatus comprising:

a feature amount computation unit configured to divide an input video signal into a plurality of scenes each comprising at least one temporally-continuous frame, and compute a statistical feature amount for each scene;

an encoding parameter generator to generate an encoding parameter for each scene based on the statistical feature amount computed by the feature amount computation unit;

a number-of-generated-bits prediction unit configured to predict the number of bits to be generated when the input video signal is encoded using the encoding parameter generated by the encoding parameter generator;

an encoding parameter correcting unit configured to correct the encoding parameter based on a result of the prediction of the number of generated bits which is obtained by the number-of-generated-bits prediction unit;

an encoder to encode the input video signal using the corrected encoding parameter and generate an encoded bit stream; and

an output unit configured to output the encoded bit stream generated by the encoder as an encoded output, wherein the feature amount computation unit includes a classification unit configured to classify the plurality of scenes into a plurality of scene types, based on the statistical feature amount relating to a motion vector, and the encoding parameter generator includes a setting unit configured to correct a frame rate as well as a quantization step by setting weight parameters to the frame rate and the quantization step size, respectively, for each scene according to the scene types.

3. The video encoding apparatus according to claim 2, wherein the setting unit is configured to set the weight parameters to the frame rate and the quantization step size for macro blocks of frames to be encoded for each scene on the bases of the statistical feature amount relating to a distribution of luminance for each macro block.

11. The apparatus according to claim 2, wherein the setting unit includes a computing unit configured to compute the frame rate and the quantization step from a sum of a value determined by a bit rate, a video size and a representative value for each scene and a value determined by a motion vector of an object in the scene.

12. The apparatus according to claim 2, wherein correcting the frame rate as well as the quantization step includes computing the frame rate and the quantization step by an equation as follows:

FR(j)=a*MVnum_—

j+b+W_—

FR

where FR(j) represents the frame rate, MVnum_j denotes a representative value for a j-th scene, a and b denote coefficients for a bit rate and a video size specified by a user, and W_FR denotes a weight parameter, and

QP(j)=c*MVnum_—

j+d+W_—

QP

where QP(j) represents the frame rate, c and d denote coefficients for a bit rate and a video size specified by a user, and W_QP denotes a weight parameter.

13. The method according to claim 2, wherein the setting unit includes a reset unit configured to reset the bit rate exceeding an upper limit value or a lower limit value.

4. A video encoding method comprising:

dividing an input video signal into a plurality of scenes each comprising at least one temporally-continuous frame;

computing a statistical feature amount for each scene;

generating an encoding parameter for each scene based on the statistical feature amount computed by the feature amount computing step;

predicting the number of bits to be generated when the input video signal is encoded using the encoding parameter generated by the encoding parameter generating step;

correcting the encoding parameter based on a result of the prediction of the number of generated bits which is obtained by the number-of-generated-bits predicting step; and

encoding the input video signal using the corrected encoding parameter to generate an encoded bit stream,

wherein the encoding parameter generating step includes correcting a frame rate as well as a quantization step size by setting weight parameters to the frame rate and the quantization step size, respectively, for macro blocks of frames to be encoded for each scene on the bases of the statistical feature amount relating to a distribution of luminance for each macro block.

5. A video encoding method comprising:

dividing an input video signal into a plurality of scenes each comprising at least one temporally-continuous frame;

computing a statistical feature amount for each scene;

generating an encoding parameter for each scene based on the statistical feature amount computed by the feature amount computing step;

predicting the number of bits to be generated when the input video signal is encoded using the encoding parameter generated by the encoding parameter generating step;

correcting the encoding parameter based on a result of the prediction of the number of generated bits which is obtained by the number-of-generated-bits predicting step; and

encoding the input video signal using the corrected encoding parameter to generate an encoded bit stream, wherein the feature amount computing step includes classifying the plurality of scenes into a plurality of scene types, based on the statistical feature amount relating to a motion vector, and the encoding parameter generating step includes correcting a frame rate as well as a quantization step size by setting weight parameters to the frame rate and the quantization step size, respectively, for each scene according to the scene types.

6. The method according to claim 5, wherein the encoding parameter generating step includes setting the weight parameters to the frame rate and the quantization step size, respectively, for macro blocks of frames to be encoded for each scene on the bases of the statistical feature amount relating to a distribution of luminance for each macro block.

14. The method according to claim 5, wherein correcting the frame rate as well as the quantization step includes computing the frame rate and the quantization step from a sum of a value determined by a bit rate, a video size and a representative value for each scene and a value determined by a motion vector of an object in the scene.

15. The method according to claim 5, wherein correcting the frame rate as well as the quantization step includes computing the frame rate and the quantization step by an equation as follows:

FR(j)=a*MVnum_—

j+b+W_—

FR

where FR(j) represents the frame rate, MVnum_j denotes a representative value for a j-th scene, a and b denote coefficients for a bit rate and a video size specified by a user, and W_FR denotes a weight parameter, and

QP(j)=c*MVnum_—

j+d+W_—

QP

where QP(j) represents the frame rate, c and d denote coefficients for a bit rate and a video size specified by a user, and W_QP denotes a weight parameter.

16. The method according to claim 5, wherein correcting the frame rate as well as the quantization step includes resetting the bit rate exceeding an upper limit value or a lower limit value.

7. A recording medium having a computer program recorded therein for encoding an input video signal, the computer program comprising:

instruction means for instructing the computer to divide an input video signal into a plurality of scenes each comprising at least one temporally-continuous frame and compute a statistical feature amount for each scene;

instruction means for instructing the computer to generate an encoding parameter for each scene based on the statistical feature amount;

instruction means for instructing the computer to predict the number of bits generated when the input video signal is encoded using the encoding parameter;

instruction means for instructing the computer to correct the encoding parameter based on a result of the prediction of the number of generated bits; and

instruction means for instructing the computer to encode the input video signal using the corrected encoding parameter and generate an encoded bit stream,

wherein the means for instructing the computer to generate the encoding parameter includes means for instructing the computer to correct a frame rate as well as a quantization step size by setting weight parameters to the frame rate and the quantization step size, respectively, for macro blocks of frames to be encoded for each scene on the bases of the statistical feature amount relating to a distribution of luminance for each macro block.

17. The recording medium according to claim 7, wherein the means for instructing the computer to correct the frame rate as well as the quantization step size includes means for instructing the computer to compute the frame rate and the quantization step from a sum of a value determined by a bit rate, a video size and a representative value for each scene and a value determined by a motion vector of an object in the scene.

18. The recording medium according to claim 7, wherein the means for instructing the computer to correct the frame rate as well as the quantization step size includes means for instructing the computer to compute the frame rate and the quantization step by an equation as follows:

FR(j)=a*MVnum_—

j+b+W_—

FR

where FR(j) represents the frame rate, MVnum_j denotes a representative value for a j-th scene, a and b denote coefficients for a bit rate and a video size specified by a user, and W_FR denotes a weight parameter, and

QP(j)=c*MVnum_—

j+d+W_—

QP

where QP(j) represents the frame rate, c and d denote coefficients for a bit rate and a video size specified by a user, and W_QP denotes a weight parameter.

19. The apparatus according to claim 7, wherein the means for instructing the computer to correct the frame rate as well as the quantization step size includes means for the computer to reset the bit rate exceeding an upper limit value or a lower limit value.