通信工程专业英语 Lesson 4 Audio Encoding & Video Encoding 第4课 音频编码与视频编码 邓 磊 denglei@dgut.edu.cn https://leideng.github.io/communication-english/ (Some pictures are from the Internet) 东莞理工学院 电子工程与智能化学院 2018.09.11/12

Outline Technical Contents Technical Terms Structures and Sentences Audio Encoding 音频编码 Video Encoding 视频编码 Technical Terms Structures and Sentences

Technical Contents: Audio Encoding Audio Encoding: converting an (analog) audio signal into a digital audio signal Telephone: 8000 samples/sec; each sample has 7 bits (North America and Japan) or 8 bits (Europe). Audio CD: 44100 samples/sec; each sample has 16 bits.

Technical Contents: Video Encoding Video encoding: converting a three-dimensional (analog) video signal into a one-dimensional digital signal.

Technical Terms audio adj. 音频 logarithm ['lɒgərɪð(ə)m] n. 对数 Exponent 指数 Base 底数 audio adj. 音频 audibility n. 可听性；可闻度 logarithm ['lɒgərɪð(ə)m] n. 对数 exponentiation [,ekspənenʃɪ'eɪʃ(ə)n] n. 幂运算 quantization n. 量化 quantize vt. 量化 quantization noise 量化噪声

Technical Terms monaural [mɒn‘ɔːr(ə)l] adj. 单声道的 stereo [ˈsterɪəʊ] n.&adj. 立体声（的） retina ['retɪnə] n. 视网膜 flicker vi. & n. 闪烁 interlacing n. 隔行扫描 interlace vt. 使交错；使交织 progressive adj. 逐行扫描的

Technical Terms monochrome [‘mɒnəkrəʊm] n. 单色 chrominance [‘krəʊmɪnəns] n. 色度 luminance [‘luːmɪn(ə)ns] n. 亮度 intensity [ɪn'tensɪtɪ] n. 强度

Technical Terms dynamic range 动态范围 power level 功率电平 lower limit/bound 下限 upper limit/bound 上限 linear superposition 线性叠加 electron beam 电子束 three additive primary colors 加性三基色 composite signal 复合信号

Technical Terms ADC abbr. Analog-to-Digital Converter 模数转换器 DAC abbr. Digital-to-Analog Converter 数模转换器 PCM abbr. Pulse Code Modulation 脉冲编码调制 MPEG ['em,peg] abbr. Moving Picture Experts Group 运动图象专家组 RGB abbr. Red, Green, and Blue 红绿蓝

Structures and Sentences If a sound wave is not a pure sine wave, but a linear superposition of sine waves where the highest frequency component present is f, then it is sufficient to make samples at a frequency 2f. 如果声波不是纯正弦波，而是最高频率为f的多个正弦波的线性叠加，那么按照2f的频率进行采样就足够了。

Structures and Sentences Sampling more often is of no value since the higher frequencies that such sampling could detect are not present. 因为没有更高的频率成分出现，所以更高的采样频率就毫无价值。 be of no value 毫无价值 be of great value 非常有价值 be of great significance/importance 很有意义/很重要 Be of scientific interest 有科学价值

Structures and Sentences Rather than increase the frame rate, which would require using more scarce [skeəs] bandwidth, a different approach is taken. Instead of displaying the scan lines in order from top to bottom, first all the odd scan lines are displayed, then the even ones are displayed. 我们没有采用提高帧率的方法，因为其需要更多宝贵的带宽，我们采用了另外一种方法。扫描线不是自顶至底依次显示，而是先显示奇数扫描线再显示偶数扫描线。

Thank You!