Lossless audio codec
ape
Higher bit rate
Higher bit rate
The following are the characteristics of common audio file formats.
Playing or processing audio files in a computer, that is, converting audio files from digital to analog, is also composed of sampling and quantization. The lowest frequency of sound that the human ear can hear is 20Hz to the highest frequency 20 Hz, and the human ear can't hear it above 20 Hz, so the maximum bandwidth of audio is 20 Hz, so the sampling rate needs to be between 40 and 50 Hz, and each sample needs more quantization bits. The standard of audio digitization is that the signal-to-noise ratio is 16 bits-96dB per sample. PCM adopts linear pulse code modulation, and the length of each quantization step is the same. This standard is used to make audio files.
CD format: orthodox descent
What is the best audio format in the world today? CD, of course. So when it comes to audio format, CD is naturally the forerunner. In the "open file type" of most playback software, you can see *. CDA format, that is, CD audio track. The standard CD format is 44. 1K sampling frequency, 88K/ s rate and 16 quantization bits. Because the CD track can be said to be almost lossless, its sound is basically loyal to the original sound, so if you are an audio enthusiast, CD is your first choice. It will make you feel the sound of nature. A CD can be played in a CD player or in a computer through various playing software. The CD audio file is a *. CDA file, which is only an index information, does not really contain sound information, so no matter what the length of CD music is, you should put *. The CDA file seen on the computer is 44 bytes long. Note: * in CD format cannot be copied directly. CDA file to hard disk for playback. You need to use audio capture software like EAC to convert files in CD format into WAV. If the quality of optical drive is up to standard and EAC parameters are set properly, it can be said that audio capture is basically lossless. I recommend you to use this method.
be harmless
Is a sound file format developed by Microsoft, which conforms to the PipfResource exchange file format.
WINDOWS platform and its applications support file specifications for saving audio information resources of WINDOWS platform. "*.WAV" format supports MSADPCM and CCITT A.
LAW and other compression algorithms support various audio bits, sampling frequencies and channels. Like CD format, the sampling frequency of standard WAV file is 44. 1K, the rate is 88K/ s, and the quantization bit is 16. See, the quality of WAV file is similar to that of CD, and it is also a popular audio file format on PC at present. Almost all audio editing software
But the disadvantage is that the size is too "huge".
AIFF and au
By the way, the AIFF (Audio Interchange File) developed by Apple is mentioned here.
Format) format and AU format developed for UNIX system are very similar to WAV, and these common music formats are also supported in most audio editing software.
MP3: Popular
MP3 format was born in Germany in 1980s. The so-called MP3 also refers to the audio part of the MPEG standard, that is, the MPEG audio layer. According to the difference of compression quality and coding processing, it is divided into three layers, which correspond to three kinds of sound files: * .mp1* .mp2/* .mp3. It should be noted that the compression of MPEG audio files is lossy compression. MPEG3-3 audio coding has a high compression ratio of10:12:1,while basically keeping the low audio part undistorted, but sacrificing the high audio part from 12KHz to 16KHz in the sound file. Music files with the same length are stored in * * .mp3 format, generally only * *110. WAV file, and the sound quality is not as good as CD format or wav format Because it has small files and good sound quality; So at the beginning of its appearance, no other audio format can match it, thus providing good conditions for the development of * * .mp3 format. Until now, this format is still all the rage, and its position as the mainstream audio format is hard to shake. But the copyright problem of MP3 music has not been solved, because MP3 has no copyright protection technology, which means anyone can use it clearly.
There are many sampling frequencies for MP3 compressed music. The sampling frequency of 64Kbps or lower can save space, and the standard of 320Kbps can also achieve extremely high sound quality. We use Flawn Hoff's equipment.
MP3 encoder of IIS Mpeg ly ear 3 (the best encoder now) MusicMatch jukebox
6.0 encode a 3-minute song at the frequency of 128Kbps, and get a 2.82MB MP3 file. The default CBR (fixed sampling frequency) technology can sample a song at a fixed frequency, while VBR (variable sampling frequency) can increase the sampling frequency to obtain higher sound quality when the music is "busy", but the generated MP3 file may not be played on some players. We set the level of VBR to be basically the same as that of the previous CBR file, and generate VBR.
MP3 file 2.9MB.
MIDI: composer's favorite
People who play music often should often hear MIDI (Musical Instrument Digital).
MIDI allows digital synthesizers to exchange data with other devices. The MID file format is inherited from MIDI. MID file is not recorded sound, but a set of instructions that record sound information and then tell the sound card how to reproduce music. This MIDI file only needs about 5 ~ 1 0kb of music per minute. Nowadays, MID files are mainly used for original musical instruments, amateur performances of pop songs, game tracks and e-cards. *. * effect. Mid file playback depends entirely on the grade of sound card. * the biggest use. Mid format belongs to the field of computer typesetting. *.MID files can be written in composition software, or the music played by an external sequencer can be input into the computer through the MIDI port of the sound card to make *. Intermediate file.
WMA: the most powerful
WMA (Windows Media audio)
The format is Microsoft's heavyweight player with tough background, and the sound quality is better than MP3 format, even better than RA format. Like the VQF format developed by Yamaha Company in Japan, it aims to achieve a higher compression ratio than MP3 by reducing data traffic but maintaining sound quality. The compression ratio of WMA can generally reach about 1: 18. Another advantage of WMA is that content providers can use DRM (digital).
Rights management) solutions, such as Windows Media Rights Manager.
7. Increase copy protection. This built-in copyright protection technology can limit the playing time and times, even the playing machine. This is good news for music companies that have been overwhelmed by piracy. In addition, WMA also supports audio streaming technology, which is suitable for play online on the Internet. As the pioneer of Microsoft's seizing online music, it can be said that it is leading in technology and gaining momentum. It is more convenient to install additional players such as MP3, while Windows operating system and Windows.
Seamless media player allows you to play WMA music directly, as long as you have installed windows operating system, the new version of Windows Media.
Player7.0 adds the function of directly converting CD into WMA sound format. In the newly produced operating system window,
In XP, WMA is the default encoding format. Everyone knows what happened to Netscape, and now the wolf is coming again. WMA is a format that can adjust the sound quality during recording. The same format, good sound quality can be comparable to CD, high compression rate can be used for network playback. Although it is not very popular on the Internet now, with the large-scale promotion of Microsoft, it has been recognized and strongly supported by more and more websites. In the field of online music, it is almost equal to * * .mp3, and it is also carving up the world laid by Real in terms of online playing. Therefore, almost all audio formats feel the pressure of WMA format.
At present, the most common formats supported by MP3 are MP3 and WMA. Because MP3 is lossy compression, the emphasis is on the sampling rate, which is generally 44. 1KHZ. There is also a bit rate, that is, data stream, which is generally 8-320KBPS. When encoding MP3, let's see if it supports variable bit rate (VBR). Most MP3 players now support it, which can reduce the effective file size. WMA is an audio format promoted by Microsoft, which is relatively smaller than MP3.
RealAudio: flowing melody
RealAudio is mainly suitable for online music appreciation on the Internet. At present, most users are still using Modem with a speed of 56Kbps or lower, so typical playback is not the best sound quality. Some download websites will prompt you to choose the best real file according to your modem speed. At present, real has several file formats: RA(RealAudio) and RM(RealMedia).
G2), RMX (real audio
Safety), and so on. The characteristics of these formats are that they can change the sound quality with the different network bandwidth, and on the premise of ensuring that most people can hear smooth sound, the audience with richer bandwidth can get better sound quality.
Recently, with the general improvement of network bandwidth, Real Company is launching a format for network broadcasting, which can reach the sound quality of CD. If your RealPlayer software can't handle this format, it will remind you to download a free upgrade package.
VQF: Nobody cares.
VQF islands
A format developed by Yamaha company, the core of which is to reduce data traffic but maintain sound quality to achieve higher compression ratio, can be said to be advanced in technology, but it is difficult to use because of poor publicity. *.vqf can be played with Yamaha's player. At the same time, Yamaha also provides software to convert from *. Wav file to *. Vqf file.
This document lacks characteristics and publicity, and now almost the death penalty has been declared.
OGG: A New Generation Audio Format
Og's full name should be OGG· vorbis.
Is a new audio compression format, similar to the existing music format, such as MP3. But one difference is that it is completely free, open and without patent restrictions. OGG
One outstanding feature of Vobis is that it supports multiple channels. With its popularity, it will not be a dream to listen to DTS-encoded multi-channel works with walkman in the future.
Volbis
Is the name of this audio compression mechanism, Ogg is the name of a project to design a completely open multimedia system. At present, the plan has only realized OggVorbis.
Ogg
Vorbis files have the extension. OGG。 The design format of this file is very advanced. The OGG file created now can be played on any player in the future, so this file format can be continuously improved in size and sound quality without affecting the old encoder or player.
Ogg format is completely open source and free, which is a new format comparable to mp3.
AAC: The future is boundless.
AAC (Advanced Audio Coding) is a technology provided by Dolby Laboratories for music, which can accommodate up to 48 audio tracks with a sampling rate of 96.
KHz. Appears in 1997, which is an audio coding technology based on MPEG-2. Flawn hoff
IIS, Dolby, Apple, AT & amp； T, Sony and other companies * * * replaced mp3 format. MPEG-4 standard was introduced in 2000, and AAC re-integrated its characteristics, so it is now also called MPEG-4.
AAC, or m4a.
As a high compression ratio audio compression algorithm, AAC usually has a compression ratio of 18: 1, and some data say that it is 20: 1, far exceeding the older audio compression algorithms such as AC-3 and MP3. Generally speaking, AAC format is superior to MP3 audio at 96Kbps. Another notable feature of AAC is multi-channel feature, which supports 1 ~ 48 full-frequency track and 15 low-frequency track. In addition, AAC supports a sampling rate of 96KHz at most, and its resolution ability is comparable to that of DVD-Audio pulse code modulation. Therefore, it has been supported by DVD forum and become the standard audio coding of the next generation DVD.
APE lossless compression format
New generation lossless audio format. APE is actually a lossless compressed audio format. Huge WAV audio files can be accessed through the monkey's
Audio is a "slimming" software that is compressed into APE. 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, through the monkey's
The WAV file obtained after audio decompression and restoration can be exactly the same as the source file before compression. Therefore, APE is called "lossless audio compression format", monkey's.
Audio is called "lossless audio compression software".