MC History of MP3 players 21世纪，便携式MP3播放器 1 Apr 1989.Patented 1 Jan 1994,MPEG-2 1 Jan 1999,And here they developed are! 1 Jan 1988.MPEG 1 Jan 1992,Algorithm 26 Nov 1996.Patent established integrated Issued 1 Jan 1987,mp3 thought 1 Jan 1993,MPEG 1 Sep 1998,Enforcing the of published patent 1990 http://www.timetoast.com/timelines/ .1987-The Fraunhofer Institut in Germany began research (DAB). April 1989-Fraunhofer received a German patent for MP3 .1992-Fraunhofer's and Dieter Seitzer's algorithm was integrated into MPEG-1. .1993-MPEG-1 standard published .1994-MPEG-2 developed and published a year later. .1996-United States patent issued for MP3 .1998-Fraunhofer started to enforce their patent rights. .1999-Portable MP3 players appear. 6 ynh.cxh @ustc.edu.cn
{ynh,cxh}@ustc.edu.cn History of MP3 players 21世纪，便携式MP3播放器 6 http://www.timetoast.com/timelines/ •1987 - The Fraunhofer Institut in Germany began research (DAB). •April 1989 - Fraunhofer received a German patent for MP3 •1992 - Fraunhofer's and Dieter Seitzer’s algorithm was integrated into MPEG-1. •1993 - MPEG-1 standard published •1994 - MPEG-2 developed and published a year later. •1996 - United States patent issued for MP3 •1998 - Fraunhofer started to enforce their patent rights. •1999 - Portable MP3 players appear
KC数字音频主要应用领域 ◆应用范围 口无线电广播、电话、电视信号中的声音 口移动通信、卫星通信、音频文件 Digital audio broadcasting Digital Audio Broadcasting (DAB) Storage technologies ▣Digital audio player ▣Compact Disc(CD) ▣DVD-Audio ▣Super Audio CD ▣Blu-ray Disc(BD) 7 ynh.cxh @ustc.edu.cn
{ynh,cxh}@ustc.edu.cn 数字音频主要应用领域 应用范围 无线电广播、电话、电视信号中的声音 移动通信、卫星通信、音频文件 Digital audio broadcasting Digital Audio Broadcasting (DAB) Storage technologies Digital audio player Compact Disc (CD) DVD-Audio Super Audio CD Blu-ray Disc (BD) 7
MC Technical Details of Lossy Audio Compression Formats Audio compression Algorithm Sample Rate Bit rate Latency format AAC MDCT,Hybrid Subband 8 kHz to 192 kHz301 8 to 529 kbit/s(stereo) 20-405ms37 (AAC-HE) AC3 MDCT 32,44.1,48kHz 32 to 640 kbit/s 40.6ms 4.75,5.15,5.90,6.70,7.40,7.95, AMR ACELP 8kHz 10.20,12.20kbit/s 25ms GSM-HR VSELP 8 kHz 5.6 kbit/s 25ms GSM-FR RPE-LTP 8 kHz 13 kbit/s 20-30ms GSM-EFR ACELP 8kHz 12.2 kbit/s 20-30ms HVXC Speech 8 kHz 2 or 4 kbit/s 36ms 8.16.24.32.40.48.56,64.80.96. MP3(MPEG-1,2,2.5 MDCT,Hybrid Subband 8,11.025,12.16.22.05,24. 112,128.144,160,192,224,256 >100ms Audio Layer Ill) 32.441,48kHz 320 kbit/s Musepack Subband 32,37.8.44.1,48kHz 3 to 1300 kbit/s Vorbis(Ogg) MDCT 1 Hz to 200 kHz variable >100ms Windows Media Audio MDCT 8,11.025,16,22.05,32,44.1, 4 to 768kbit/s >100ms Pro 48.88.2.96kHz http://en.wikipedia.org/wiki/Comparison_of_audio_codecs (ynh,cxh @ustc.edu.cn
{ynh,cxh}@ustc.edu.cn Technical Details of Lossy Audio Compression Formats http://en.wikipedia.org/wiki/Comparison_of_audio_codecs
MC Technical Details of Lossless Audio Compression Formats Audio compression format Algorithm专 Sample Rate Bits per sample Latency ALAC Lossless 44.1 kHz to 192 kHz 16.244g 7 4.3ms-92ms(46.4ms FLAC Lossless 1 Hz to 655350 Hz 8.16.20.24.(32) typical) Monkey's Audio Lossless 8.11.025,12,16.22.05,24,32,44.1, 2 48 KHz RealAudio Lossless Lossless Varies(see article) Varies (see article) Varies True Audio Lossless 0-4 GHz 1to>64 Lossless, varies in lossless mode:2.2 minimum in lossy WavPack Lossless 1 Hz to 16.777216 MHz Hybrid mode Windows Media Audio 8.11.025.16,22.05,32.44.1,48.88.2. 16,24 >100ms Lossless Lossless 96 kHz Lossless 指处理对象是数字音频（采样、量化后得到的声音样本） 9 ynh.cxh @ustc.edu.cn
{ynh,cxh}@ustc.edu.cn Technical Details of Lossless Audio Compression Formats 9 Lossless 指处理对象是数字音频 （采样、量化后得到的声音样本）
KC数字音频的研究对象 ◆音频(Audio)信号 ▣频率范围为20Hz~20kHz的信号 一般来说，人的听觉器官能感知的声音频率大约在20~20000 Hz之间，不同的人耳存在差异 ◆话音(speech)信号 ▣人的发音器官发出的声音频率大约是803400Hz;人说话的 信号频率通常为300~3000Hz,这种频率范围的信号称为话音， 也称作语音 ◆常见音频 口电话话音（窄带话音）2003400Hz/13bits ▣宽带话音50~7000Hz/16bits ▣调频广播20~15kHz/16bits ▣高质量音频20~20kHz/16bits 10 ynh.cxh@ustc.edu.cn
{ynh,cxh}@ustc.edu.cn 数字音频的研究对象 音频(Audio)信号 频率范围为20 Hz～20 kHz的信号 一般来说，人的听觉器官能感知的声音频率大约在20～20000 Hz之间，不同的人耳存在差异 话音(speech)信号 人的发音器官发出的声音频率大约是80～3400 Hz；人说话的 信号频率通常为300～3000 Hz，这种频率范围的信号称为话音， 也称作语音 常见音频 电话话音（窄带话音） 200～3400Hz / 13bits 宽带话音 50～7000Hz / 16bits 调频广播 20～15kHz / 16bits 高质量音频 20～20k Hz / 16bits 10