Video encoding method and apparatus

A video coding and coding technology, which is applied in the field of rate control in video coding, can solve the problems of image quality degradation, large changes in image characteristics, and low accuracy of global complexity measurement

Inactive Publication Date: 2007-04-04
KK TOSHIBA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, there is a case where the number of bits per picture is allocated by using a value of the global complexity measure that is not appropriate for the I picture, which causes a problem that the number of bits to be allocated to the I picture is inappropriate
Also, because the time difference between an I picture and the next I picture is large, the picture characteristics vary greatly between I pictures
For this reason, the accuracy of the global complexity metric for updating I-pictures is low, which may be one reason for image quality degradation

Method used

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Examples

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no. 1 example

[0045]1 shows a video encoding apparatus according to a first embodiment of the present invention, said apparatus has a target bit rate (BR) input unit 1, a frame rate (FR) / reordering delay (M) / GOP number input unit 2, an automatic The initial parameter determination unit 3 and the rate control encoder 9 are adapted. The adaptive initial parameter determination unit 3 has a first quantization parameter (QP1) determination unit 4, a calculator 5 (referred to as a bit number calculator) for calculating the number of encoding bits for each image type, using the bit number of each image type Number of temporary bit rate calculator 6, second quantization parameter (QP2) determination unit 7 and initial parameter determination unit 8.

[0046] Figure 2 shows details of the rate control encoder 9 in Figure 1 . This example represents the main part of a video encoder implemented in relation to H.264. A video signal 101 is input to a subtractor 201 , which is the object to be coded, ...

no. 2 example

[0090] Next, a second embodiment of the present invention will be described. In the second embodiment, not only the initial value of the quantization parameter QP but also the initial value of the global complexity measure are determined in the initial parameter determination unit 7 of FIG. 1 .

[0091] Hereinafter, the global complexity measure will be explained. The global complexity measure is a parameter used in the system adopted in TM5 of MPEG-2. For TM5, a model is assumed where the product of the average quantization parameter and the number of coded bits is a constant value for each picture type unless the picture changes. In the formula below, X is the global complexity measure for each image type, S is the number of bits for each image type, and Q is the average quantization parameter for each image type.

[0092] X i = S ...

no. 3 example

[0102] Next, a third embodiment of the present invention will be described. In this embodiment, the adaptive initial parameter determination process S15 shown in FIG. 9 is executed in the video encoding device shown in FIG. 1 . In FIG. 9 , the process in step S12 is added to the adaptive initial parameter determination process S14 in the second embodiment shown in FIG. 7 .

[0103] Specifically, in the third embodiment, first in the same manner as in the second embodiment, the quantization parameter QP suitable for the target bit rate BR is calculated in the initial parameter determination unit 7 shown in FIG. 1 (step S9) . Next, the initial value of the global complexity measure is calculated using QP in the same manner as in the second embodiment (step S11). Thereafter, based on the quantization parameters QP1 and QP2, the number of bits of each image type I1, I2, P1, P2, B1, B2, the constant parameters in the update formula of the global complexity measure are determined ...

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Abstract

A video encoding method includes encoding n pictures included in a video image using a first quantization parameter, calculating first number-of-encoded-bits information indicating number of encoded bits of every picture type, multiplexing a set frame rate by an average first-number-of-encoded-bits per picture calculated from the first-number-of-encoded-bits information to obtain a first bit rate, encoding the n pictures using a second quantization parameter, calculating second number-of-encoded-bits information indicating number of encoded bits of every picture type, multiplexing the set frame rate by an average second number-of-encoded-bits per picture calculated from the first-number-of-encoded-bits information to obtain a second bit rate, calculating a third quantization parameter, using the first bit rate, first quantization parameter, second bit rate, second quantization parameter and target bit rate, and performing the rate control using the third quantization parameter as an initial value.

Description

technical field [0001] The present invention relates to rate control, and more particularly to rate control in video coding. Background technique [0002] Since moving image data, that is, video data has a large amount of data, compression coding is performed when distributing or accumulating video data. In compression encoding, it is necessary to encode video data at a bit rate that does not exceed the transmission capability at the time of distribution, and at the number of bits that does not exceed the guaranteed capacity at the time of accumulation. In order to address the above-mentioned needs, the bit rate is controlled in video coding by using techniques such as constant bit rate (CBR) control or variable bit rate (VBR) control, such as IDG Japan Inc. edited by Wataru Kameyama and Tsuyoshi Hamamura (January 2003 28) as described in the IDG Information and Telecommunications Series MPEG-1 / MPEG-2 / MPEG-4 Digital Broadcasting Textbook (Volume 1). In CBR control, the ent...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N7/50H04N7/26H04N19/50H03M7/30H04N19/107H04N19/114H04N19/124H04N19/149H04N19/159H04N19/177H04N19/194H04N19/503H04N19/593H04N19/61H04N19/625H04N19/91
CPCH04N19/00781H04N19/00375H04N19/00721H04N19/00278H04N7/26164H04N19/00181H04N19/00272H04N19/00218H04N19/0006H04N19/0003H04N19/00096H04N19/0029H04N19/00193H04N19/00284H04N19/00266H04N19/00369H04N19/197H04N19/159H04N19/176H04N19/172H04N19/196H04N19/149H04N19/115H04N19/61H04N19/107H04N19/126H04N19/152H04N19/177H04N19/174H04N19/179H04N19/577
Inventor 武田奈穗美中条健松村淳
Owner KK TOSHIBA
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