Please introduce some information about MD, MP3 and MP4, and it's better to talk about the differences.

Mini Disc (short for mini magneto-optical disc) is a music storage medium which was officially mass-produced by Sony Corporation of Japan in 1992. Now it is generally called MD as portable MD machine. The audio compression algorithm adopted by MD machine has two formats: ATRAC/ATRAC 3 (the compression ratio with CD-DA is 1: 5 and 1: 1 respectively), and MD machine itself can be divided into recordable/downloadable MD machine (with writing head and reading laser head) and single-player MD machine (only with laser head for reading data). Due to the use of specially developed magnetic heads, laser heads, mechanical parts, etc., it can be said that MD machine is a high-tech product integrating optical, magnetic, mechanical and electrical technologies. Compared with ordinary portable CD players and tape drives, MD machine not only has a sound quality similar to that of CD (only similar, but the actual sound quality is not as good as that of CD), but also has a reliable data storage period and a rewritable function of tape drives. For ordinary consumers, MD machine can be simply regarded as the neutralization of CD machine and tape machine. MD allows users to record music by themselves, and all sounds can be recorded from all sound source devices through appropriate connection methods (analog audio cable, optical fiber cable, microphone). At the same time, users can edit the music recorded on MD discs by naming, dividing, moving and deleting. Because MD, like CD, records music information in a digital way, it can also change tracks quickly, play in sequence, randomly and repeatedly. Moreover, the advantage of digitally recording music is that it can avoid the background noise in the tape player, and provide users with purer music enjoyment

MP3

. Portable MP3 player is commonly known as MP3 player.

It is a portable player used to play MP3 music (now it is compatible with wma,wav and other formats). Portable MP3 player was originally developed by Korean Wen Guangzhu and Moon & Hwang) was invented in 1997, and applied for related patents.

MP4

At present, many consumers have a vague understanding of MP4, so they simply think that MP4, the next generation of MP3, can play MPEG-4. Later, with the accumulation of knowledge, they have a more systematic understanding. It's a long story about the exact concept of MP4, because it can be described in one word-"chaos" in terms of MP4 brand, market, product specifications and configuration standards. I don't know whether it's hype or trend. In the eyes of merchants now, all players that can touch one side of the video are called MP4. This statement is simple and intuitive, and it seems to be basically consistent with the author's vague understanding.

mp5

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In fact, their similarity is that they all have a PLAYER, but they are different with different functions. MD is what people who listen to music need, with a higher price and the best sound quality. The market of MP3 is rather chaotic, and the sound quality of MP3 is not as good as that of MD in theory. Besides the decoding rate of music files of MP3 itself, there is also the problem of different decoding chips adopted by various MP3 manufacturers. Different decoding chips have a vital impact on the sound quality of MP3, so MP3 buys decoding chips. . MP4 actually adds one more video function to MP3. Now, some derivative products, such as MP4, or MP4 mobile phones, are all derivatives of MP4. The best MP4 in China is Meizu's MINI series. You can know what MP4 is, or the Ipod video of MAC!