WAV is an audio format provided by Microsoft Windows itself. Due to the influence of Windows itself, this format has become a de facto universal audio format. To put it bluntly, it is actually a clone version of the Apple computer in AIFF format. Usually we use WAV format to save some uncompressed audio, but in fact the design of WAV format is very flexible (very complicated), and the format itself does not conflict with any media data. In other words, with software support, you can even store pictures in WAV format. The reason for this is that each piece of data stored in the WAV file has its own independent identifier, which can tell users what data it is. On the WINDOWS platform, more than 20 compression formats, such as ADPCM, GSM, CCITT G.7 1 1, G.723, can be stored in WAV files through ACM(Audio Compression Manager) structure and corresponding drivers (commonly referred to as codecs and encoders/decoders here). And, of course, MP3 format.
Although WAV file can store compressed audio or even mp3, its purpose is to store audio data and use it for further processing, instead of listening like mp3. At present, all audio playing software and editing software support this format, and take this format as one of the default file saving formats. These softwares include: Sound Forge, Cool Edit Pro, WaveLab and so on. Because the support of WAV is so extensive, it can be said that even if Windows quits the historical stage, WAV format will not die out.
Old and strong-
The second one is mp3 that changed the world. I believe everyone will agree with this metaphor. Mp3 is the research result of Fraunhofer-IIS Institute (). Mp3 is the first practical lossy audio compression coding. Before the appearance of mp3, the compression ratio of general audio coding can reach 4: 1 even though it is lossy compression, which is very good. But mp3 can achieve the compression ratio of 12: 1, which makes mp3 popular rapidly. The reason why mp3 can achieve such a high compression ratio and maintain a fairly good sound quality is that it adopts perceptual audio coding technology, that is, it uses the characteristics of human ears to cut off the components that human ears can't hear, while trying to maintain the original sound quality.
Measuring the compression ratio of mp3 files is usually expressed in terms of bit rate. The English name of this term is bps: bit per second, which means how many binary bits can be used to represent audio per 1 second. Generally, the higher the bit rate, the larger the compressed file, but the more components are retained in the music, the better the sound quality. Because of the relationship between bit rate and file size and sound quality, mp3 encoded by vbr(Variant Bitrate) appeared later. The characteristic of this coding method is that it can dynamically select the appropriate bit rate according to the coding content. Therefore, the result of coding is to ensure the sound quality while taking into account the file size, and the result is very popular. In fact, the mp3 coding standard originally supported this compression method, but the third-party tool, Xing Encoder, was the first to realize this function. It used to be a very famous company (in those days, many computers relied on this company's Xing player to watch VCD and listen to mp3).
Because mp3 is the first coding scheme with lossy compression in the world, it can be said that all playback software supports it, otherwise it will have no vitality. In terms of production, many third-party coding tools have also been produced. However, after Fraunhofer-IIS announced that it would levy royalties on encoders, many of them disappeared. At present, the encoder that belongs to open source code and is free is LAME (Lame is not an Mp3 encoder). This tool is recognized as the best mp3 compression tool for compressing sound quality. In addition, almost all audio editing tools support opening and saving mp3 files. Recently, Fraunhofer-IIS also charged copyright fees for mp3 decoders that did not charge copyright fees before. Fraunhofer-IIS realized that mp3 was going downhill and finally made a profit while collecting money. It should be said that by now, MP3 is really tired. Many new generation coding technologies have been able to provide much better sound quality than MP3 at the same bit rate. Especially music lovers scoff at the sound quality of mp3. However, due to the great influence of mp3, there are many softwares supporting mp3, not to mention many hardware players supporting mp3, such as MPMAN, DiscMan, CD/VCD/DVD players and so on. In a word, it is still the most popular audio compression technology in the world, so it will take a long time for it to really quit the stage.
The originator of network streaming media-real media
After the popularity of the Internet, real media appeared. This file format has almost become synonymous with network streaming media. RA and RMA are two file types in real media. It was invented by Real Networks Company (), and its characteristic is that it can provide users with good enough sound quality for online listening under very low bandwidth (as low as 28.8kbps). This function was simply the gospel of the majority of netizens in the early days of the Internet. That is, after the emergence of real media, related applications such as online broadcasting, online teaching and online on-demand surfaced, forming a new industry.
In fact, the principle of network streaming media is very simple. Simply put, it is to divide the original continuous audio into small packets with sequence tags, transmit these small packets through the network, and then reassemble these packets in order when receiving them. If the network quality is too poor and some packets are not received or delayed, it will skip these packets and not play them to ensure that the content that users are listening to is basically continuous. It is such a simple truth, but it has contributed to another legend on the Internet.
Because the real media is developed in an extremely harsh network environment, the sound quality of the real media is not so good, including at high bit rate, even worse than mp3. Especially for a long time, the real network only focused on adding various new functions to the real media, such as advertising spots, ignoring that with the improvement of network speed and the popularity of broadband networks, users' requirements for quality are also constantly improving. Later, Real Networks cooperated with Sony to realize high bit rate and high fidelity compression by using Sony's ATRAC technology (MD compression technology), but these measures always bring users a feeling of being late. Because the purpose of real media is to listen online, it is not suitable for editing, so there are not many corresponding processing software. Some mainstream software can support reading/writing of real media, and the software that can realize direct editing is a real media editor provided by Real Net and bundled in a real media encoder. But its role is very limited. This is a different world from Windows Media now.
Domineering-Windows Media
Microsoft is indispensable to everything. After realizing the importance of network streaming media to the Internet, Microsoft immediately launched Windows Media to compete with real media, and began to say no to other audio compression technologies: no direct support. In the Windows XP version, all mp3 compression functions originally provided have been removed.
Windows Media () is also a network streaming media technology, which is essentially the same as real media. However, Real Media is a limited and open technology, and rtsp (Real-time Streaming Protocol) and other network transmission protocols are submitted to the Network Working Group (NoRFC2326), while Windows Media has not disclosed any technical details, allegedly in order to better protect copyright, so it should be completely closed, and a transmission protocol called mms(Multi-Media Stream Multimedia Stream) has been created. Together, we can see Microsoft's ambition to unify the rivers and lakes.
The original version of Windows Media didn't get much praise, especially in terms of sound quality, which was despised by those "golden ears" netizens on the Internet. However, after several versions of updates, the latest Windows Media 9 technology carries many new features, and the cooperation with Windows Media Player is not the same. Especially in audio, Microsoft is the only solution that can provide various audio compression technologies (no distortion, no distortion, no voice), and it has a great momentum covering everything. This is also the consistent feature of Microsoft: although the quality of my products is not the best, it is definitely the most convenient and integrated. At present, Windows Media is still in the promotion period, players and encoders can be downloaded for free, and servers are bundled in the Windows server version without additional charges. These means are constantly increasing their market share. And because of the influence of Microsoft, there are many softwares supporting Windows Media. Although it is also used for listening and cannot be edited, almost all audio editing tools on the Windows platform provide read/write support for it, even third-party players support it. Simple direct editing can be achieved through the Windows Media file editor introduced by Microsoft itself. Recently, Microsoft also launched a version of Windows XP Media Center, which strengthened the role of Windows as a home entertainment center by bundling Windows Media 9 technology and related entertainment media software in Windows XP. If Microsoft continues to maintain its monopoly position in the operating system, especially the desktop operating system, the future of Windows Media will be brilliant.
Midi—— The Bridge between Computer and Electronic Musical Instrument
MIDI technology was not originally invented for computers. This technology was originally applied to electronic musical instruments to record musicians' performances for later replay. However, with the introduction of sound cards supporting MIDI synthesis in computers, MIDI has officially become an audio format. Many people mistakenly think that MIDI is used to record music, which is wrong. The content of MIDI not only records the music score, but also records the playing method of each note, so some MIDI files are not pleasant to play, while others are good. There are two versions of MIDI itself, Universal MIDI and Universal MIDI 2. Many third-party nonstandard technologies are also derived from MIDI, such as the famous X-MIDI (or XG), which was invented by Yamaha Corporation of Japan. Based on the original MIDI with 128 musical instruments, it has been expanded to 5 12 musical instruments, adding more playing controls, which can be restored by Yamaha's own wave table playing software or hardware supporting X-MIDI. In addition, DLS (downloadable sound) technology was introduced by the General MIDI Association (the international organization of MIDI specifications) to make up for the shortcoming that the sound of musical instruments synthesized by MIDI is always inferior to that of real musical instruments. This technology enables MIDI files to create sounds close to the effects of real instruments by attaching recordings (samples) of real instruments to MIDI files. However, the main problem of this technology is that the MIDI files with musical instruments after sampling are too large, generally more than 4 megabytes (users of this size are of course looking for mp3), which affects the popularization of this technology.
Because of its advantages and particularity, MIDI is believed to be a technology that will exist for a long time. Ordinary MIDI files are supported by many players, but to achieve good results, you must install a soft wave table, such as the once famous WinGroove, Roland virtual sound canvas and Yamaha S-YXG player. With the cooperation between Microsoft and Roland () and the addition of DirectMusic in DirectX, the soft wave table has become the standard configuration of Windows system. It should be noted that for the X-MIDI format, you must use Yamaha's own player to get a good playback effect. For example, the sound card with Yamaha YMF724/740 as the chip used to sell well, and the player with X-MIDI was S-ysg 100.
If you want to edit MIDI files, you can use the famous software Cake Walk Pro and sonar (); X-MIDI can use Yamaha XGWorks. There are also some music software, such as Sibelius (). But these softwares are very expensive. There are also some related software supporting notation in China, such as TT composition ().
Lossless audio compression–-ape
APE is a lossless compressed audio format. Huge WAV audio files can be "slimmed down" by the monkey's audio and compressed into APE. Similarly, APE can also be restored to WAV through monkey's audio, and then burned to CD. Sometimes it is used for network audio file transmission, because the compressed APE file capacity is less than half of the WAV source file, which can save transmission time. More importantly, the WAV file obtained after decompression and restoration of monkey's audio can be exactly the same as the source file before compression. Therefore, APE is called "lossless audio compression format" and Monkey's audio is called "lossless audio compression software". Unlike using professional data compression software such as WinZip or WinRAR to compress audio files, compressed APE audio files can be played directly.
There are many others, see the links below.