问题 单项选择题

下列关于压缩编码方法的描述中,错误的是()。

A.啥夫曼编码将出现概率大的信源符号用长码表示,出现概率小的信源符号用短码表示

B.预测编码法、变换编码法以及矢量量化编码法均属于源编码,都是有损压缩编码

C.离散傅立叶变换(DFT)将时域信号变换到频域上,用较少的数据来表示大量的信息

D.信息熵编码是一种统计编码,是一种无损压缩编码

答案

参考答案:A

解析:

对于多媒体数据,按照压缩的原理可分为熵编码、源编码和混合编码。其中,源编码包含预测编码法、变换编码法以及矢量量化编码法,属于有损压缩编码,见表7-6。

啥夫曼编码是最著名的熵编码,它将出现概率大的信源符号用短码表示,而出现概率小的信源符号用长码表示,于是平均码长接近信息熵的理论值。因此,选项A的说法有误。

单项选择题
单项选择题

The "standard of living" of any country means the average person’s share of the goods and services which the country produces. A country’s standard of living, (1) , depends first and (2) on its capacity to produce wealth." Wealth" in this sense is not money, for we do not live on money (3) on things that money can buy. "Goods" such as food and clothing, and "services" such as transport and " (4) ". A country’s capacity to produce wealth depends upon many factors, most of (5) have an effect on one another. Wealth depends (6) a great extent upon a country’s natural resources. Some regions of the world are well supplied with coal and minerals, and have a fertile soil and a (7) climate; other regions possess none of them.

Next to natural resources (8) the ability to turn them to use. China is perhaps as well (9) as the USA in natural resources, but suffered for many years from civil and (10) wars, and (11) this and other reasons was (12) to develop her resources. (13) and stable political conditions, and (14) from foreign invasion, enable a country to develop its natural resources peacefully and steadily, and to produce more wealth than another country equally well (15) by nature but less well ordered.

A country’s standard of living does not only depend upon the wealth that is produced and consumed (16) its own borders, but also upon what is indirectly produced through international trade. (17) , Britain’s wealth in foodstuffs and other agricultural products would be much less if she had to depend only on (18) grown at home. Trade makes it possible for her surplus manufactured goods to be traded abroad for the agricultural products that would (19) be lacking. A country’s wealth is, therefore, much influenced by its manufacturing capacity, (20) that other countries can be found ready to accept its manufactures.

17()

A.In short

B.For example

C.First of all

D.On one hand