H.264与MPEG-4编码标准深度解析：图像通信新高度

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《H.264和MPEG-4视频压缩中文版》是一本专注于图像处理领域的经典著作，特别关注MPEG4和H.264编码协议的深入解析。H.264/MPEG-4 AVC是国际电信联盟（ITU）电视和广播工程组（TVCG）与国际标准化组织/国际电工委员会（ISO/IEC）MPEG标准委员会联合开发的最新视频压缩标准。相较于早期标准，H.264提供了显著更高的压缩效率，使得非交错和交错视频编码更加高效，即使在高比特率下也能实现更佳的视觉质量。 H.264的一个关键优势在于它对非交错视频的支持，这在处理高清、逐行扫描的视频内容时表现出色。同时，它也支持交错视频编码，适应不同的显示格式，提高了编码的灵活性。新标准允许编码器在数据组织上具备更高的容错性和抗丢失能力，这对于网络传输中的视频流尤为重要。然而，这种提高的编码效率和灵活性是以增加复杂性为代价的。相比于先前的标准，H.264的设计更为精细，编码过程包含更多的算法和技术细节，如帧内预测、变换编码、熵编码、运动估计和补偿等。这些高级特性使得编码器需要更强大的计算能力和更复杂的编码策略。在论文中，作者Atul Puria、Xuemin Chen和Ajay Luthra首先概述了H.264/MPEG-4 AVC所采用的关键视频编码工具和技术。这部分内容可能包括：宏块分割和编码（MB partitioning）、变量化（Transform Coding）、熵编码（Entropy Coding，如Huffman编码和Context-adaptive binary arithmetic coding）、以及帧间预测（Inter-frame Prediction）和帧内预测（Intra-frame Prediction），这些都是H.264能实现高效压缩的核心技术组件。此外，论文还可能讨论了诸如自适应码率控制（Adaptive Bit Rate Control）、环内编码（Loop Filtering）、以及多参考帧（Multiple Reference Frames）等高级功能，这些都是为了优化编码性能并适应不同应用场景的特性。总结来说，这本书将帮助读者深入了解H.264标准背后的原理，掌握如何在实际图像处理和视频压缩应用中利用这一先进技术。

prediction modes are deﬁned when a 16  16

partition is used. For chrominance pixels, 4

different modes are deﬁned, that are similar in

nature to the 4 modes of 16  16 luma intra-

prediction process. Both chroma blocks, Cb and

Cr, use the same prediction mode.

2.5.7. Inter prediction

This block includes both motion estimation

(ME) and motion compensation (MC). The ME/

MC process performs prediction. It generates a

predicted version of a rectangular array of pixels,

by choosing another similarly sized rectangular

array of pixels from a previously decoded refer-

ence picture and translating the reference array to

the position of the current rectangular array. In

AVC, the rectangular arrays of pixels that are

predicted using MC can have the following sizes:

4  4, 4  8, 8  4, 8  8, 16  8, 8  16, and

16  16 pixels. The translation from other posi-

tions of the array in the reference picture is

speciﬁed with quarter pixel precision. The ﬁlter

to perform the translation uses 6 taps in the x and

y dimensions, plus another step that uses 2 taps.

The foregoing is primarily concerned with luma

values; motion compensation is applied to chroma

values in a slightly different way, with smaller

arrays of samples due to the 4:2:0 sampling.

Chroma MVs at

pixel resolution are derived

from transmitted luma MVs of

pixel resolution,

and simpler ﬁlters are used for chroma as

compared to luma.

2.6. Encoding process

Next, Fig. 4 provides an overview of the major

encoding functions and decisions that must be

performed starting at the access unit level. The

individual steps involved in encoding as per this

ﬁgure are shown in Figs. 5–7.

2.6.1. Slice header and MB syntax encoding

Different elements in the slice header and MB

syntax are coded using different code types.

Fig. 5(a) illustrates how an encoder must switch

between Exp-Golomb coding and ﬁxed length

coding when encoding these syntax elements.

At the macroblock level, the main decision is

whether to code the MB as an intra-MB or an

inter-MB as shown in Fig. 5(b).

2.6.2. Rate control and mode decision

This block is responsible for bit allocation and

rate control by controlling how each macroblock

is coded. These issues are addressed in encoding

discussion in Section 6 of this paper.

2.6.3. Intra-MB and inter-MB encoding

Fig. 6(a) shows a detailed diagram of the

process for intra-MB encoding. The encoding

ARTICLE IN PRESS

Deblocking Filter

MB Encoding

Reconstruction

Deblocking

Enabled?

Frame Buffer

Last MB in

the Slice?

Last Slice in the

Access Unit?

Yes

Access Unit Encoding

Yes No

Slice Header and

MB Syntax

Encoding

Rate Control and

Mode Decision

Compressed Stream

Fig. 4. Encoding ﬂow diagram for access units.

A. Puri et al. / Signal Processing: Image Communication 19 (2004) 793–849802

tasks performed here depend ﬁrst on whether

I-PCM encoding is performed. If I-PCM encoding

is performed, the MB can be coded directly. If

I-PCM encoding is not performed, the intra-

prediction, transform and quantization operations

are performed on the block and then either

CABAC or CAVLC encoding is utilized to

generate the compressed stream.

Fig. 6(b) shows a detailed diagram of the

process for inter-MB encoding. The encoding

tasks performed here depend ﬁrst on whether the

MB is a skipped MB. If the MB is a skipped MB,

the MB

16  16 MV or the direct-mode MV must

be calculated depending on whether the MB is in a

P-slice or a B-slice, respectively. If the MB is not a

skipped MB, a check to see if direct mode is being

used is performed. If direct mode is being used, the

direct mode MVs must be derived. If direct mode

is not being used, the differential MVs must be

encoded. Motion compensation and prediction is

then performed followed by the transform and

quantization operations. The next step is to check

to see if the block is being coded. If not, the

encoder can proceed directly to MB reconstruc-

tion. If the block is being coded, then either

CABAC or CAVLC encoding is performed before

MB reconstruction.

2.6.4. MB reconstruction

A MB may be classiﬁed as ‘‘coded’’ or as ‘‘not

coded’’. As shown in Fig. 7 both types of MBs

require prediction blocks for reconstruction. In

case of ‘‘coded’’ MB, in addition, reconstructed

prediction error block is needed and is generated

by, inverse quantization of corresponding quan-

tized transform coefﬁcient block, and then fol-

lowed by inverse transform of the inverse

quantized block. This reconstructed prediction

error block is then added to the prediction block

to generate the reconstructed MB. For ‘‘not

coded’’ MB, only prediction block is needed.

2.7. Decoding process for residue blocks

In Fig. 8, we now present a ﬂow diagram of the

decoding process for the residual signal. First, it is

ARTICLE IN PRESS

Exp-Golomb

Coding?

Exp-Golomb

Code

Encoding

Fixed

Length Code

Encoding

Slice Header and MB

Syntax Encoding

Yes

Last

Element?

Yes

Intra-MB ?

Intra-MB

Encoding

Inter-MB

Encoding

MB Encoding

Yes

(a) (b)

Fig. 5. Encoding ﬂow diagrams for (a) slice header and MB syntax, (b) MB encoding.

A. Puri et al. / Signal Processing: Image Communication 19 (2004) 793–849 803

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