Analysis:
1.WAV format is a sound file format developed by Microsoft, also known as waveform sound file. It is the earliest digital audio format and widely supported by Windows platform and its applications. WAV format supports a variety of compression algorithms and a variety of audio bits, sampling frequencies and channels. It uses the sampling frequency of 44. 1kHz and the quantization bit of 16, so the sound quality of WAV is almost the same as that of CD. However, WAV format requires too much storage space for communication and propagation.
2.MIDI is the abbreviation of musical instrument digital interface, also known as musical instrument digital interface, which is a unified international standard for digital music/electronic synthetic musical instruments. It defines the way in which electronic devices such as computer music programs and digital synthesizers exchange music signals, and specifies the cables, hardware and data transmission protocols between electronic musical instruments from different manufacturers and computers, which can simulate the sounds of various musical instruments. MIDI files are files in MIDI format, and some instructions are stored in MIDI files. Send these instructions to the sound card, and the sound card will synthesize sound according to the instructions.
3. Everyone is familiar with the music format CD with CDA extension, and its sampling frequency is 44. 1kHz, 16 quantized bits. CD storage takes the form of audio track, also called "red book" format, and records waveform stream, which is an approximate lossless format.
4. The full name of 4.MP3 is MPEG- 1 Audio Layer 3, which was incorporated into the MPEG specification in 1992. MP3 can compress digital audio files with high quality and low sampling rate. In other words, audio files (mainly large files, such as WAV files) can be compressed to a smaller extent, and the loss of sound quality is very small (the human ear simply does not notice this loss of sound quality).
5.MP3Pro was developed by Swedish coding technology company, including two major technologies: one is the unique decoding technology from coding technology company, and the other is the decoding technology jointly researched by French Thomson Multimedia Company, the patent holder of MP3, and Flawn Hof Integrated Circuit Association. MP3Pro can improve the original sound quality of MP3 music without changing the file size. It can compress audio files at a lower bit rate and maintain the sound quality before compression to the greatest extent.
6.WMA (Windows Media Audio) is the representative work of Microsoft in the field of Internet audio and video. WMA format aims to achieve a higher compression rate by reducing data traffic but maintaining sound quality, and its compression rate can generally reach 1: 18. In addition, WMA can also add anti-copy function through DRM (Digital Rights Management) scheme, or add restrictions on playing time and times, even playing machines, which can effectively prevent piracy.
7.MP4 is based on AT&T; A2b music compression technology with perceptual coding as the key technology is a new music format jointly released by American Network Technology Corporation (GMO) and RIAA. MP4 adopts the encoding technology of file copyright protection, which can only be played by specific users, effectively ensuring the legitimacy of music copyright. In addition, the compression ratio of MP4 reaches 1: 15, which is smaller than that of MP3, but the sound quality has not decreased. However, because only specific users can play such files, their circulation is far from that of MP3.
8.SACD (SA = Super Audio) was officially released by Sony. Its sampling rate is 64 times that of CD format, that is, 2.8224MHz, and SACD's playing frequency bandwidth is 100kHz, which is 5 times that of CD format. The 24-bit quantization digit far exceeds that of CD, and the sound details are richer and clearer.
9.QuickTime is a digital streaming media launched by Apple at 199 1. It is oriented to video editing, website creation and media technology platform. QuickTime supports almost all mainstream personal computing platforms and can provide real-time digital information flow, workflow and file playback functions through the Internet. The existing versions are QuickTime 1.0, 2.0, 3.0, 4.0 and 5.0. In version 5.0, many new technologies are also integrated, such as players that support the highest A/V playback quality.
10.VQF format is an audio compression technology jointly developed by Yamaha and NTT***, and its compression ratio can reach 1: 18. Therefore, the file volume after VQF compression is 30% ~ 50% smaller than that of MP3 under the same conditions, which is more convenient for online transmission and has excellent sound quality, close to CD (65438). However, VQF did not disclose the technical standards, so it has not been popularized so far.
1 1.DVD audio is a new generation of digital audio format with the same size and capacity as DVD video. It is a DVD disc with music format, and the sampling frequencies are "48kHz/96kHz/ 192kHz" and "44.1khz/88.2khz/176.4khz". Although the low sampling rates of 192kHz and 176.4kHz are dedicated to 2-channel playback, you can record up to 6 channels. However, recording with two channels of 192kHz/24b or six channels of 96kHz/24b can accommodate more than 74 minutes of recording, and the dynamic range is 144dB, which has an outstanding overall effect.
12. Everyone is familiar with Sony's MD(MiniDisc). MD can store stereo music sampled at 44. 1khz in a small disk for 60 ~ 80 minutes because it uses ATRAC algorithm (adaptive acoustic transcoding) to compress the sound source. This is an audio decoding system based on psychoacoustics, which can compress the audio of CD to about 1/5 of the original data without obvious loss of sound quality. ATRAC makes use of the psychoacoustic characteristics of human hearing (spectrum masking characteristics and time masking characteristics) and the limited resolution of human ears to signal amplitude, frequency and time, and does not encode and transmit the components that human ears can't feel, thus reducing the storage of some data accordingly, thus ensuring the sound quality and achieving the purpose of reducing the volume.
13.RealAudio is a file format introduced by Real Neorks company. Its biggest feature is that it can transmit audio information in real time, especially when the network speed is slow, it can still transmit data smoothly. So RealAudio is mainly suitable for play online on the Internet. At present, there are three RealAudio file formats: RA(RealAudio), RM(RealMedia, RealAudio G2) and RMX(RealAudio Secured). The similarity of these files is that the sound quality varies with the network bandwidth. On the premise of ensuring that most people can hear smooth sound, listeners with wider bandwidth can get better sound quality.
14.Liquid Audio is a website that provides paid music downloads. It provides copyright protection for music by adopting its own unique audio coding format. The audio format of liquid audio is called LQT. If you want to play music in this format on your computer, you must use one of the liquid player and the real jukebox. These files can't be converted to MP3 and WAV formats, so audio files in this format can't be shared and burned to CD. If you want to burn a liquid audio file to a CD, you must use a recording software and a CD burner that support this format.
15.Audible has four different formats: Audible 1, 2, 3 and 4. Audible website mainly sells audio books on the Internet, and provides protection for the goods and files it sells through one of four audio formats. Each format mainly considers the sound source and the listening equipment used. 1, 2, and 3 formats adopt different degrees of speech compression, while format 4 adopts a lower sampling rate and the same decoding method as MP3, and the obtained speech sounds are clearer and can be downloaded from the Internet more effectively. Audible uses its own desktop playback tool, namely Audible Manager. With this player, you can play files in audio format stored on a PC or transferred to a portable player.
16. VOC files often encountered in DOS programs and games are digital sound files generated together with the sound blaster card, which are similar in structure to WAV files and can be easily converted to each other through some tools and software.
17.AU file, mainly used for multimedia sound on the Internet. AU file is a digital sound file under UNIX operating system. Because the early Web server on Inter was mainly based on UNIX, this file became the only standard sound file used on WWW.
18.AIFF(。 AIF) is a sound file format developed by Apple and supported by Macintosh platforms and applications.
19. Amiga (. SVX): The sound file format developed by Commodore is supported by the Amiga platform and application, and does not support compression.
20.MAC voice (. Snd): The sound file format developed by Apple Computer Company supports Macintosh platform and various Macintosh applications, and supports partial compression.
2 1.S48 (stereo, 48kHz) adopts MPEG- 1 layer 1 and MPEG- 1 layer 2 (Mp 1, Mp2 for short), which is easy to edit and cut, so it is widely used in radio stations.
22.AAC is actually the abbreviation of advanced audio coding. AAC consists of Flawn Hof IIS-A, Dolby and AT&; An audio format developed by T * * * is a part of MPEG-2 specification. The algorithm adopted by AAC is different from MP3, and AAC improves the coding efficiency by combining other functions. AAC's audio algorithm far exceeds some previous compression algorithms (such as MP3, etc. ) in terms of compressibility. It also supports up to 48 tracks, 15 low-frequency tracks, more sampling rate and bit rate, multi-language compatibility and higher decoding efficiency. In a word, AAC can provide better sound quality on the premise that it is 30% smaller than MP3 files.