MP3 player is actually a small computer with specific functions. In the small body of the MP3 player, there is an MP3 player storage （ Memory card ）MP3 player display（ LCD Display screen), MP3 player a central processor MCU （ micro controller ）Or MP3 player decoding DSP（ Digital Signal Processor ）Etc. microprocessor It is the "brain" of the player, which is used to receive the playback control selected by the user and transfer the currently played song information display stay LCD Up, then up to the data signal processing The chip sends instructions to enable it to process accurately sound signal 。 Digital Signal processor First, use the decompression algorithm to convert MP3 File decompression , then use Digital to analog converter Digitize Information conversion Waveform information, and then the amplifier will signal amplification And sent to Audio port Finally, we can listen to beautiful music through headphones connected to the audio port. At the same time, we can use its own data cable（ USB ）Connect with the computer and use the network to Audio files Importing MP3 can not only listen to music, but also carry out necessary English Listening training 。 In short, it is the crystallization of the wisdom of this information world. The birth of the first MP3 player in the world is actually a Small story The story goes back to March 1997, South Korea Samsung One from the company division manager Moon Korean Spelling) Sir, back from a business trip in the United States Seoul On his plane Notebook computer Look at a report sent to him by his colleague. This is a brief report on image, text and MP3 music synthesis. When Moon finished reading and took off his earphones, he found that the passengers beside him were listening to the MD. Moon was immediately inspired: if the MP3 music files on the computer can also be taken out directly and played with an independent player, it would not be the best Music Walkman Is it? After returning to South Korea, he proposed this idea to the then president. Unfortunately, Samsung was in the process of organizational restructuring at that time and had no time to consider Moon's development proposal. Six months later, Asian Financial Crisis The occurrence of Samsung Mr. Moon was also forced to retire early due to the huge impact. After leaving the Samsung head office, Mr. Moon entered the Samsung subsidiary Saehan (Shihan) as president, and turned his idea into reality in Saehan. In 1998, he launched the world's first MP3 player, MPMan F10. MPMan， It means the combination of MP3 and WALKMAN. The volume of MPMan F10 is 70x90x16.5mm, about four 1.44M floppy disk The stack is so large and weighs 65g, which is very light. MPMan F10 has no mechanical parts, Signal-to-noise ratio Up to 70dB, Distortion rate 0.01-0.1%. Audio track can be displayed during playback Play time , can arrange playing sequence, support bass/midrange amplification, battery Status detection And display, depending on 2 Nickel metal hydride battery It can also be played for 8 hours, even in modern times, it will not appear backward. MPMan F10 was developed at that time to allow users to download songs from paid music websites. Unfortunately, Saehan Company did not have enough strength to carry out large-scale promotion. In addition, MPMan F10 used flash memory, which was extremely expensive at that time, and soon lost the battle with MD. Although it has not attracted much attention, the emergence of MPMan F10 has started the MP3 market since then, and many Korean companies have started the research, development and production of MP3. Until today, South Korea is still in the leading position in the MP3 field.
Living Korean MPman F10 After bringing surprises to people, Diamond in the United States took the lead and launched Rio at the end of 1998 PMP 300, which is the first MP3 that impressed the whole world. The biggest advantage of Rio PMP300 is that it can download MP3 on the Internet at no cost. However, the rich MP3 resources on the Internet have brought infinite surprises and fun as well as copyright protection New problems. The imperial league was soon record industry tycoon RIAA （ Recording Industry Association of America ）He took the case to court on the ground that Rio PMP300 infringed intellectual property rights. The matter ended in the victory of Diamonds, and the copyright dispute became the biggest publicity of Rio PMP300, The Rio PMP300 has become a "star" that has been heard all over the world. It is incredibly popular around the world at a price of 170 dollars. At this time, people really knew the existence of the "MP3 player", leading many people to mistakenly believe that the Rio PMP300 is the first MP3 player in the world today. [1]
The first 2.5-inch hard disk MP3
——Creative NOMAD Jukebox
Entering the 21st century, the rapid development of MP3 makes people no longer satisfied with flash memory MB Is the capacity in units. In January 2000, Big Brother in the audio hardware field innovatively launched the world's first 2.5 inch hard disk MP3 - NOMAD Jukebox, which uses Fujitsu The 6.4GB 2.5-inch hard disk serves as storage medium It can store MP3 music equivalent to more than 100 CDs. Its capacity is far more than that of flash memory MP3 at that time, but its volume is also very amazing. It is even larger than an ordinary CD walkman, and its shape is very similar to that of a CD walkman. Although hard disk media is used, in order to ensure that music can be played smoothly during movement, innovation has designed an 8MB shockproof cache that can support 5 minutes, so that music will not appear even when going out and moving Jump track Phenomenon. At the same time, NOMAD Jukebox is the earliest Direct recording function One of the MP3s of. The emergence of direct recording makes MP3 break the limitation of relying on computers to obtain resources. Of course, the freedom to convert CDs into MP3 anytime and anywhere has also attracted the "attention" of RIAA, but fortunately, innovation comes from Singapore RIAA can only be out of reach. At present, direct recording MP3 is already popular. The birth of innovative NOMAD Jukebox, with its super expensive price, exaggerated power consumption and contrarian portability, has not really brought hard disk MP3 into people's lives. Until Apple iPod The emergence of... Although the idea of using hard disk as the storage medium of MP3 was not first proposed by Apple, the iPod is the best product to implement this idea. It is the iPod that really set off the trend of hard disk MP3. iPod Born in October 2001, as an MP3 player, it is not outstanding in many aspects: high price, average sound quality, short use time, lack of support for Windows, etc., but it is the first to combine Internet music with MP3 walkman Bundle sales Products. Many people are willing to pay a small amount of money to download a single song from Apple's official website, or use the monthly unlimited download. The iPod really makes the record company profit, so it has the dual support of consumers and record companies. More importantly, apart from the beautiful appearance and humanistic creation of the product itself, the iPod has become a fashion and a symbol of MP3 music culture. Having an iPod does not mean that you have the best MP3 player, but that you are a person who understands life and has taste. When something becomes a culture, or even a symbol, it will be difficult to replace, which is the biggest reason why iPods have been popular from one generation to four generations!
First support WMA Encoded MP3 ——Samsung yp u6
No matter in any field, there will never be a situation of "monopoly". Just as MP3 music format is becoming increasingly popular on the Internet, more and more digital music formats are emerging for the network, among which Apple's iTunes and Microsoft WMA of. WMA Yes Windows Media Audio Coded file format , as long as it passes Windows Media Player CD can be transcribed into WMA format digital music. Under the same sound quality, WMA files occupy only half of the space of MP3 files, and only 64Kbps Coding rate WMA can achieve sound quality close to CD. The support for WMA music format means you can hear more and better music. Unlike the previous coding, WMA supports the anti duplication function Windows Media By adding protection to Rights Manager, you can limit the playing time and times, even the playing machine. The MP3 music format has not made much progress except for the use of variable coding rate. Although the MP4 and MP3 Pro formats appeared later, the lack of support from manufacturers and players made these two formats unpopular. In addition, Microsoft's strong promotion of WMA industry insiders It is only a matter of time before MP3 is finally replaced by WMA or other music formats. In September 2002, the world's first support WMA MP3 with encoding function was born, which means that Samsung yp u6 not only supports playing WMA music format, but also can directly transcribe various audio files into WMA format. Compared with other MP3 with WMA decoding function, Samsung yp u6 has realized "full support for multiple Audio format ”。 Although hard disk MP3 brings large capacity storage space However, it also brings problems such as poor portability and high power consumption. The initial hard disk MP3 did not pose too big a threat to the traditional flash MP3 One inch Micro hard disk There are 1.5G and 4G capacities. The problems of poor portability and high power consumption caused by hard disk MP3 have been solved by NOMAD MuVo2 one by one, and its signal-to-noise ratio nominal It reached a record 98dB. Large capacity, small size and good sound quality are superior to general flash MP3. In 2004, when the development of MP3 in capacity, appearance and sound quality could no longer attract more attention, it began to turn to multi-function. Just like what happened to mobile phones, people's requirement for MP3 is no longer to enjoy music alone, but to be able to play multiple roles like mobile phones.
As the world's first flash color screen MP3, Xinli MP301 The launch of has aroused great concern in the MP3 market. Color screen mobile phone It started with 256 colors, but the Sinley MP301 was in place with 2.2 "65000 colors STN screen , the resolution reaches 160 × 128 pixels, although not TFT material High brightness In addition, the high resolution makes the MP301's image display effect quite exquisite, and it still performs well even in strong light, which is even better than most color screen mobile phones. In addition to the addition of color screens, MP301 also supports e-book , picture browsing and Game function In addition, when browsing e-books, pictures or playing games, the MP301 can also listen to FM radio or play MP3 music at the same time, so that you can enjoy watching and listening at the same time. [2] Multi functional integration, yes consumer electronics Of Development trend 。 After China launched its first color screen MP3, South Korea's iRiver seized the opportunity to launch MP3 with a camera. IRiver iFP-1090 follows the classic appearance of iRiver's proud "Iron Triangle" and the improvement of many revolutionary functions. It has a 1.2 inch 260000 color LTPS screen and a 300000 pixel camera. Its camera adopts a retractable design and can rotate 180 °, supporting three times digital zoom Unfortunately, the photos taken can be used like mobile phones Communication network Pass the picture directly to others. In order to cope with the high power consumption caused by color screens and cameras, iRiver has equipped the iFP-1090 with a high-capacity built-in lithium battery, which can support 36 hours of continuous operation. Although it is a built-in lithium battery, it has a detachable design, which is convenient for users to replace new batteries. [3] MP3 -- DMTECH DM-AV10 believes that many friends have heard of "MP4". The existing word "MP4", just like "MP3", has two meanings: one is MP4 music format, and the other is a player that supports video playback. However, the relationship between them is not the same as that between MP3 music format and MP3 player.
DMTECH DM AV10MP4 music format is a new music format Compression ratio It is higher than MP3 music format (15:1-20:1), but its sound quality is better than MP3 music format. More importantly, MP4 music files have built-in include and copyright holder Relevant text, image and other copyright descriptions, and embedded player. Double click in Windows directly to run playback. Although MP4 music format is more advanced than MP3 music format, it can't compete with MP3 music format without copyright. There are few players that really support MP4 music format, which is almost invisible in the market. Therefore, it is generally called "MP4" in the market Video player It is not really a player that supports MP4 music format encoding, but a player that supports MPEG-4 The file format of MP3 players is also called MPEG-4. Well, in order to avoid confusion, hereinafter referred to as "MP4", it means MPEG-4 to watch with you. Similar products to MP4 include PMP (Potable Media Play) and PMC (Potable Media Center ）Among them, PMC is the most common. It uses Microsoft's operating system and belongs to Openness With Software upgrade The ability to play any of the latest file formats can be achieved by upgrading the software, but MP4 can not be compared with it. The first player in the world that supports video playback in classic MP4 style is not PMC, but DM-AV10 of DMTECH in South Korea. It supports MPEG-4 SP (Simple Profile), DivX 3.11/4.0/5.03/5.1.1 format file playback, and can also play WMV ASF 、 AVI 、MPEG、 MPG 、 VOB 、 DAT And other file formats can be converted into playable ones with the accompanying software video file , you can also use AV cable Put TV VCD 、 DV D、DV、 DC And other real-time video recording as high-quality MPEG-4 files. The birth of MP3 player has brought a fatal blow to the traditional walkman - WALKMAN, CD walkman and MD. Once upon a time, the struggle between MP3 and MD became the most popular topic in the industry. At that time, even most people thought that MP3 would lose to MD due to the sound quality, but in fact, the development of MP3 far exceeded the expectations of MD supporters. Until today, MP3 has become the mainstream product in the walkman market and the most widely used personal portable electronic product after mobile phones. [4] 
MP3 glasses When calendar When I turned to this page in 2007, MP3 Walkman It has experienced several years of development, and the competition in the walkman market is also becoming fiercer. Almost every week or even every day, new MP3 products will be launched, and its development speed is amazing. This is a year of intense competition, not between MP3 manufacturers, but between two very different portable audio players. MP3 vs. MD, figuratively speaking, is the competition between a newborn and an adult. During this period, MD player It has gradually declined, whether R909, the representative of traditional MD, or Sony The N10, the representative of the NET MD released to compete with MP3, can't save the situation. In this period, the most unforgettable is IRIVER's iFP-180T, which is a classic in the minds of countless people, and a classic that is still difficult to surpass. [6] During the development of MP3 in this year, the focus on sound quality is obviously the theme of this period. Various MP3 audio decoding chips have been launched, including SIGMATEL3520 and Philips PNX0102 chip Most prominent. and OGG Music format The addition of provides strong support for improving the sound quality of MP3. During this period, many products that are still talked about by people, such as IAUDIO U2 And IRIVER iFP-999, etc., the sound of these MP3 players is still regarded as the standard to measure the sound quality of other MP3 players. [7] In the course of MP3 development this year, it is undoubtedly the most important to develop MP3 screens into color screens. From black and white to seven colors OLED , then to 4096 color CSTN, and finally to 65536 color TFT Even more high-end 260000 color TFTs, this is an era when MP3 becomes colorful. In the development process of color screen MP3, Xinli's MP301 and ipod nano are undoubtedly the most brilliant products in this period. Although Xinli's MP301 is a 2004 product, it is the world's first color screen MP3, and its significance is self-evident. If Xinli's MP301 is the key to opening the door of color screen MP3, then the iPod nano is opening the door. When Apple Inc When the iPod nano, the first color screen MP3 product in its production history, was released, it was no less sensational than the launch of Windows XP. In less than a year, the sales volume of more than 10 million sets well proved this. When consumers are not satisfied with MP3's single function of listening to music, they hope to have a product that can listen to music and watch video. And when Aino After the introduction of a V60 MP3, the door of MP3 video playback has finally been opened. V60 is the first model adopted in China Actions 2097 chip to support video playback of MP3, after the launch of the entire MP3 market caused a strong sensation. Other well-known domestic MP3 manufacturers such as Taidian ONDA 、 Meizu Taking advantage of the waste heat of the market, they launched their own products of the Juli 2097 scheme. The MP3 market has also suddenly become lively, and the competition between video MP3 players has become increasingly fierce. However, in such fierce competition, the real practicability of video MP3 is determined by Blue Devil RM100 This product is established. When other manufacturers are still using Torus 2097 chip, Rockchip The use of 2606 chip makes RM100 It has more powerful video playing ability Frame rate Reach a level where you can watch more smoothly. Unfortunately, the playing of APE/FLAC is still a relatively high-end technology. Currently, there are not many players on the market that can support music in these two formats, among which there are Representativeness Yes IAUDIO D2 As well as the U60 of Ainuo, D2 is much more expensive in terms of price price level Look, whether it's OPPO The price of the V3 is higher than that of the T39. In contrast, the price of the U60 is much more approachable. In the current video MP3 market, the U60 may be one of the products that can make the public consumers affordable to consume both audio and painting Main force 。 [8] 
Mp3 player The shape must be ingenious. Because it is not easy to develop MP3 molds and there are certain appearance design patents, manufacturers must position these products as high-end models, and will also spend more time. The matching of colors is very important. Usually, senior designers will pay great attention to this aspect. It is not necessary to have bright colors, but it must be reasonable to make MP3 look more noble and elegant. It has formed a strong visual impact , especially those products tailored for fashion and beauty loving MM, the color is more attractive than any function. In addition, the shell is not easy to lose color after the processing of advanced baking varnish, which can be seen from the color reflection of the shell. In terms of material selection, metal is the best, rubber Next, engineering plastic Worst of all, of course, this does not mean that MP3 players made of metal are good, but that metal is relatively more resistant, looks more beautiful, and has more texture and grade. The so-called“ Once an expert makes a move, he will know whether there is ”You can roughly judge the quality of MP3 materials by touching the MP3 case to see if it is handy. The workmanship mainly depends on the details of the product and the connection position between each part. If the shell splicing is urgent (especially the position of the battery cover), the keys are soft and comfortable, and there are no burrs and uneven body, it is basically qualified. The light weight cannot be ignored. MP3 is a walkman device, even if Appearance design If it has to be more prominent, not easy to carry or too large, it will also lose the essence of "carrying". Mirror is a very popular design at present, but the real nano mirror can clearly reflect light and be used as a mirror. The biggest defect of the mirror surface is that once it is scratched, the scar will become very obvious, just like a beauty tearing her face. The DX-8 body shape of Danding is streamline The curve radians at the upper and lower ends are different, and they look like eggs plan It is really similar, so it is named "colored egg". Science is developing, fashion is also developing, and our mobile phones have gone from simple monochrome screen Entering the era of color screen, similarly, consumption Electronics The typical representative of MP3 player has also begun to step into the color screen era, and I believe that this will certainly become the mainstream of future development. According to the color effect, the higher the number of colors, the better. The screen material is LTPS (Low Temperature Polysilicon) is better than TFT ，TFT（ thin film transistor， Thin film transistor ）Better than STN (Super Twisted Nematic), as for OLED (Organic light emitting diode) color screen has advantages in the dark, but cannot display complex pictures like TFT and STN. Because MP3 is small, Screen size It will be greatly limited, and the larger the screen is, the better it is, but it depends on the amount of display content. Under the same size, the more display content, the higher the screen resolution is, and the more delicate the picture will be, which is also conducive to adding a humanized graphic menu, so that the operation mode is close to the daily Windows habit. 
Mp3 player At the same time, the poor MP3 decoder chip will not only bring about a decline in sound quality, but also may not support MP3 audio files with high sampling rates. Such as popular music Compressed format In addition to MP3 Microsoft WMA , ogg, and MP3 pro formats Code rate It can provide better audio quality or smaller files with the same audio quality, but not all chips can support them. In addition, MP3 with better balance in sound quality and file volume VBR encoding Because the bit rate is variable, many chips cannot support MP3 files encoded in this way very well, and they can only use the lowest bit rate or Average bitrate To decode, it is shown on the screen of the player that the timing cannot move accurately, and it will move back and forth Time hopping Or the time hopping is uneven. In addition, users who require the highest audio quality often choose CBR 320kbs bit rate to compress MP3, but many chips only support MP3 with the maximum 256 kbs bit rate, which also cannot be decoded correctly. Note that the newer the product is, the more advanced the decoding chip is. Only high-end products will use high-end chips. Low end MP3 decoder It was a few years ago Stock products ， Homogenization As a result, when they sell metropolis Coupled with better headphones as a gimmick, and then the inherent disadvantage is never changed! At present, the most common chips in MP3 players on the market are Sigmatel, Actions, Sunplus (Lingyang), MosArt（ Sinosilicon ），Atmel，Telechip， ST ， PHILIPS CRYSTAL, etc. These chips are mainly produced in Taiwan and South Korea, of which Actions is the product of mainland companies, and the most common cheap MP3 player in the market Single chip The solution is Sunplus and MosArt. Place of Origin: Netherlands If we must select the best MP3 decoder chip in the market at present, there is no doubt that Philips chip Has. Philips The family's decoding chip has been famous in the industry for its "full functions, good sound quality and high price". 
Mp3 player 2、 Sigmatel Series
Origin: America
MP3 chip Market share In that case, the Sigmatel family in the United States must be well known, but the quality of Sigmatel chips is always subject to different opinions. In general, MP3 audio quality performance using Sigmatel decoding chip will be satisfactory, with beautiful sound, moderate midrange performance, insufficient sense of bass volume, and stiff treble. Its music performance is inferior to that of Philips and Telechips Chip. Origin: South Korea
South Korea ECT SKYLARK chip At present, all domestic button machines are used, but they do not support WMA. The price is about the same as STMP3410, and the functions are more comprehensive. The main features of Skylark are low power consumption and pleasant sound quality; The recording generates MP3 format files, which can be compressed optionally Bit rate ； code Direct recording function , and the compressed bit rate can be adjusted as required; built-in FM frequency modulation Radio, China, Japan and Europe can be selected, and the receiving section can be listed in player Medium; Chinese, English Korean , Japanese, etc Language selection ； Song title ID3 , synchronous display of lyrics (supporting synchronous display of Chinese song names and lyrics); Independent file deletion function, easy to use; Point A-B Multiple hearing Function; Internal memory Capacity query, you can query the capacity of internal memory. Needless to say, the representative work using KYLARK chip is Danding DX-8. Origin: America
U.S.A ATMEL Is DSP MCU Industry leader. AT89C51ND1X series chips are a DSP+MCU hybrid solution for embedded multimedia applications specially developed for mp3 industry. MP3 integrated USB using this chip, MMC embedded very small system software, with complete functions USB function Requires only 15K bytes of firmware code. This MP3 decoder and hardware Interface controller Very low power consumption. 5、 Sinosilicon
Origin: Taiwan
Taiwan MOSART chips have simple functions and are generally used for low-end products, such as no LCD display, or SD card Player. Dual chip architecture（ CPU Separate from the decoding chip). The sound quality is quite distinctive. The bass is good, and the middle and high tones are average. Place of origin: Zhuhai
Actions ATJ208564 PIN package, highly integrated. Supported formats include MP3, WMA, WMV ASF Play, support FM, chip price is cheaper. At present, many mainland manufacturers choose this ATJ208564PIN from Juli. The disadvantage is that the sound quality is ordinary and barely audible, and the performance of FM needs to be improved. The headset includes two parts, one is the MP3 itself output power High output power (two earphones add up to more than 20mW) can drive some high-end earphones with high impedance, making the sound quality more perfect; The second is the quality of the earphones themselves. It is inevitable to choose the earphones based on their appearance. The appearance of excellent earphones will certainly not be worse. The most important thing to note is that those earphones claim to be the earphones of a famous factory OEM , for propaganda. In fact, most earphones are not really OEM products It has a similar appearance, but it is not the same inside. People are afraid of being famous and pigs are afraid of being strong. Once a certain earphone model is set up Famous brand effect Many earphone manufacturers have followed the trend to produce similar products, and MP3 manufacturers are also playing a role. Therefore, we must not blindly follow merchants or some press release As described in the article, the best way is still to listen. MP3 has more and more functions. Like PDA and mobile phones, it is developing towards multi-function. It tries to absorb the functions of other products to increase the selling points of products.
● Can mobile hard disk drive : The computer directly recognizes MP3 as a mobile storage , can store various files other than music. ● Firmware update : Solve known software and hardware failures after product release, and add new functions. ● Folder browsing: different songs are stored as folders and played as a unit, without all MP3s being placed under the same directory to improve management ease of use.
● Multi language: It mainly supports simplified Chinese, traditional Chinese, Korean, Japanese, English, and some models even have 26 languages.
● A-B repetition: repeat a paragraph to facilitate learning a foreign language.
● Text reading: usually only MP3 with large screen has this function, which can be used as e-book See, some products also support the text format of PDA. If the firmware capacity is sufficient, you can also download different Chinese and foreign fonts. Automatic reel The function is also very useful. The backlight is always on when the page is automatically turned up or down, which not only saves the trouble of turning pages, but also completely makes up for the shortcomings of the small display screen. You can even listen to MP3 while reading, just like a PDA with simplified functions. ● TTS （text-to- speech , text voice reading), directly convert the text into text with MP3 voice, machine voice has no tone and rhythm conversion, which sounds strange, but it is suitable for lazy people who do not want to read. ● Dictionary: English Chinese dictionary, used for translation. Note that MP3 control keys are limited, so input English words It's not easy. ● Automatic Recording function : Through SAD (Sound Activity Detector), you can set the length of silence time. Only when there is sound, you can record, which not only saves Memory space To save time during playback. ● Remote recording: use AGC (Auto Gain Control, automatic gain control ）, adjustable sensitivity and recording quality (low, medium, high), suitable for remote external recording, such as conference. ● FM: Listen to radio stations. Many products can preset several channels without having to adjust each time.
● FM recording: transfer radio content to MP3, and some products also have FM recording.
● EQ setting: the setting of sound effect. Almost every product has several preset sound effect settings, such as ordinary, rock, jazz, popular, classical. Some MP3 players also support customized sound effect settings, which users can customize according to their own preferences.
● Direct recording: transfer the external sound source (CD/ MD Walkman , home audio, computer) are compressed into music files and stored directly on MP3. Due to the poor performance of the encoding chip built into the MP3 player, the sound quality is not as good as the music files compressed by the computer. ● Clock: The month, day and hour can be entered for time setting.
● Alarm clock: settable Timed alarm clock , you can not only beep in the earplug, but also bring your own Loudspeaker At the same time, the alarm clock will also work without earplugs. ● Scheduled shutdown: it can be set between 0 and 180 minutes for scheduled shutdown. Of course, it can also be set between 0 and 60 minutes for automatic shutdown without operation, which is most convenient at night Before going to bed listen to the music. ● Picture browser : You can not only browse the photos taken, but also enjoy the pictures downloaded from the computer. Because the screen of MP3 is small and the resolution is relatively high, the picture will look beautiful, but most screens have scale restrictions. If the scale is not correct, it will be deformed and cannot be displayed normally. ● Digital camera : Like the camera in the early days of mobile phones, the use of a 100000 - 300000 pixel 1/5.5 "CMOS lens has the main disadvantage of slow brightness sensing, so the effect of shooting in a well lit environment is better. The biggest advantage of CMOS is its small size, which is most suitable for MP3 Walkman. The camera itself has a variety of functions, which can digital zoom , multiple effects shooting, etc. Early MP3 adopts No. 5 (AA) or No. 7（ AAA ）Battery, they can be bought at will, and the price is relatively cheap (0.5-5 yuan). If it is rechargeable lithium battery (10 - 15 yuan), the use time is quite long, Play time They can all last for more than 10 hours. With an additional battery, they can meet the needs of 2-3 days. At present, most MP3s use Flash chips as storage medium The price of Flash chips has become the biggest obstacle to the popularization of large capacity. NAND Flash In the previous stage, the price was greatly reduced. The price reduction storm attacked the digital walkman market, and many brands' products have reduced prices. price cut percentage Very high, very attractive. For example, Taidian x19+ ONDA The vx8984gb has been reduced to below 200 yuan, and the cost performance ratio is extremely high. Most of the current MP3 players flash disk Function. Speed is very important when transferring files or music. USB 2.0 Also known as Hi Speed USB, its transmission speed 480Mbps=60MB/s, in other words, theoretically, 12 5MB MP3 players can be transmitted in one second. as for IEEE 1394 (Firewire), the speed is 400Mbps=50MB/s, and 10 5MB MP3 players can be transmitted in one second. Before purchasing, be sure to check whether MP3 supports USB 2.0. Currently, there are about 30-40 products on the market that support USB 2.0, generally newer models.
The quality of accessories is the most direct way to see whether manufacturers are willing to devote their efforts. Usually, MP3 players have Product specification , earplugs USB online cable 、 warranty card 、 Drive disc Higher end products also include arm straps, cloth bags, leather bags and audio clips Adapter cable , music recording cable, hanging on the neck Lanyard Ear protection film, battery, charger, etc. MP3 format is the most commonly used Support sampling rate 44.1KHz, available Bit rate It is generally 8-256Kbps. Different MP3 products have different support ranges for sampling rate and bit rate. Of course, the wider the support range, the better. For sampling rate, better products can support 48KHz. For dynamic coding VBR The file size can be smaller under the same sound quality. Some machines cannot support it. WMA is a format promoted by Microsoft, compression ratio It is generally 5-192Kbps. Under the same sound quality, WMA can be smaller than MP3 format files, so the MP3 player with this function increases its size in a disguised way Memory capacity 。 Also remind friends that the WMP provided with Windows Compressed file It is necessary to copyright protection Remove the option of, otherwise the WMA file pressed out cannot be played on MP3; WMA files downloaded from the Internet are encrypted, so players that support WMA may also fail to play. Sound that can be heard by human ears frequency range It is 20-20000Hz. The sound below 20Hz and above 20KHz is indistinguishable from the human ear. however Frequency Response Between 50Hz and 18KHz, it should be ready. Current MP3 players should be able to reach this frequency response range. However, the frequency response range is different from the sampling rate, so confusion should be avoided. Signal-to-noise ratio That is, the sound source produces the maximum undistorted sound signal intensity The ratio to the intensity of the noise emitted at the same time, usually“ SNR ”Or“ S/N ”Representation is an important parameter for measuring sound equipment such as speakers and earphones. It is also a key parameter for MP3. "Signal to noise ratio" is generally used Decibel (dB), the higher the signal-to-noise ratio, the better the effect of audio equipment. Generally speaking, at least products with signal to noise ratio above 60dB should be selected. However, at present, there is no official testing agency to assess the signal-to-noise ratio of products, so some low-quality MP3 products are also marked with high signal-to-noise ratio, which can only be verified by your own ears. If the MP3 player can hear obvious "buzzing" or "hissing" sound similar to current when no sound source signal is played, it indicates that the signal-to-noise ratio of the machine is too low for purchase. MP3 is highly integrated high-tech product , which is not only like traditional Walkman Such hardware also includes a lot of software technology, so MP3 maintenance is different from the traditional portable. In these, the author will discuss some common MP3 faults and troubleshooting methods. (See the reference website for the following figure) (1) Cannot play music player If this problem occurs, first determine whether some music cannot be played or all music cannot be played. If all music cannot be played, you can first try to format the player. Some players without drive should pay attention to the formatted file system , because the capacity of players is not large, most players only support FAT16 If the wrong file system is used for formatting, the file may not play, crash, or boot up. If only some music cannot be played, first check whether there is a problem with those music files that cannot be played, especially those from the Internet Downloaded music There are many files Extension It is MP3, but actually it is only in the MP2 format. Many players in the current market cannot play files in the MP2 format, especially some high-end machines. The simplest way to distinguish MP3 from MP2 is to use WinAMP Turn on music File, and then double-click Document Title And then take a look MPEG There is one item in the information: MPEG1.0. If layer3 is followed, it is an MP3 file; if layer1 is followed, it is an MP2 file. (2) Crash
Since most players can update their firmware, the firmware of such players is also saved in Flash Therefore, firmware may be lost or wrong during normal use. If the player operates abnormally or cannot be started, you should first try to update the firmware before starting the machine for maintenance. Because there are many types of players, the specific firmware update steps should follow the player instructions. First of all, we see the IHP120 of an iRirver. Because the USB cable on the front of the chassis is connected reversely, the player USB interface Burned, unable to use USB to transfer music, but other functions are normal. fault analysis : If the USB cable is connected reversely, it is equivalent to that the power supply of the USB interface is connected reversely. Generally speaking, the power supply is connected reversely, which will cause serious problems. However, because the IHP120 did not use bus power supply in the design, it did not cause a large area of Failure point 。 At the same time, general USB device USB interface is available during design protection circuit Therefore, before disassembling the machine, we analyzed that there should be a problem in the protection circuit. After opening the shell, we found that a capacitor at the USB connector was seriously burnt: the withstand voltage of this capacitor is 6V (positive), and it is used A multimeter After measurement, it was found that the capacitor was short circuited. After the capacitor is soldered off and connected to the USB interface, it is found that the computer can find the hardware and everything is normal. Because this capacitor is used in the USB interface for filtering, this kind of circuit design is generally intended to enhance the resistance to interference and torsion under adverse conditions, which is necessary for electromagnetic testing. But not installing it will not have other adverse effects on the machine, so you can remove it when you repair it yourself. Of course, if it is a special repair, it would be better to add it. Because this machine is for a friend to repair, and the friend is not very strict with this aspect, we removed this capacitor and used it Absolute alcohol After the surrounding circuit boards are thoroughly cleaned, the machine maintenance is completed. From the cleaned machine, you can see that the position of capacitor C16 is empty, but it does not affect the use. of course, Sometimes it is not necessarily that the capacitance is burned out because most machines also have two inductors (some are resistors) at the USB power supply inlet to limit the current. Although the inductance itself can play a certain role in filtering, because the diameter of the inductance is very small, it will be burned out when the current is high, which can protect the machine to a certain extent. If there is no response after USB is connected to the computer, you can check whether there is a problem. Generally, the machine will design them near the USB interface: the two dark components in the machine are inductance. During maintenance, you can use a multimeter to measure their resistance, which is generally below 10 Ω Infinity , they can be replaced to solve the problem. Of course, they can be used in short circuit directly under amateur maintenance. Summary: There is no USB connection to the computer Reaction time First, check the inductance (resistance) of the two current limiting devices near the USB interface (although it has a filtering function, it is more used for current limiting protection). If there is an open circuit, replace it directly, and amateur maintenance can directly short-circuit. Then check whether the capacitor connected in parallel to the USB interface is short circuited. If it is short circuited, replace it with a capacitor of the same or similar capacity. Spare time maintenance can discard it. 2、 One channel does not work properly
It is also a common fault that there is no sound in a certain sound channel or the sound is false. Because MP3 players use 3.5mm audio sockets, and the sockets are directly welded to the circuit board, this problem occurs on some machines that do not pass the welding standard during multiple plugging and unplugging. If a certain sound channel does not sound or the sound is intermittent, you can first replace the headset to determine the fault point. After it is determined that it is a machine problem, just disassemble the machine directly and use Electric iron Re solder the socket pins. Sometimes the sound will sound very false if the open weld is the socket grounding point. However, the maintenance of such problems is relatively simple. But sometimes Solder joint The solder joints look very good after being disassembled, but it is better to add some solder joints rosin (or others scaling powder ）After Repair welding 。 In spare time, you can find the fault point directly Maintain household appliances Our master will do it for you. Conclusion: When the player has intermittent sound or false sound, first replace the earphone to determine the fault point. If the earphone has no problem, then use an electric soldering iron to reweld the plug pin after disassembling the machine. 3、 Show problems
Most MP3 player screens use Flat cable It is connected to the circuit board. If the text appears on the screen, it can be checked first Slotting Check whether there is looseness, or try inserting the plug again after unplugging it. At the same time, it should be noted that this kind of plug cannot be pulled out directly. There are two small handles on both sides of the plug, which must be used first Screwdriver After pulling out the handle, the flat cable can be easily pulled out. The same is true during installation. First make sure the handle is outside, plug in the flat cable, and then press the handle inward. LCD When pulling out the flat cable, pull the handle outward in the direction indicated by the arrow, and then the flat cable can be easily pulled out. Summary: LCD display When there is a problem, you can first check whether there is a problem with the LCD cable, or try to plug and unplug the cable again. Of course, there are also some machine cables that are soldered on the circuit board. This kind of LCD must be replaced once there is a problem. It is better not to solve the problem by yourself. 4、 Internal connector
MP3 players are composed of two or more circuit boards. The circuit board and circuit board are usually connected by a plug-in. After a long time of use, this plug-in may appear poor contact There may be many kinds of faults, and in serious cases, the machine cannot be started at all. Of course, the maintenance of such problems is also relatively simple. You can directly unplug the plug, and then use a brush dipped in absolute alcohol for cleaning. After repeated cleaning for several times, you can remove the poor contact of the contact. (Use the two circuit boards connected by the plug array) (Use a brush to dip in alcohol to clean repeatedly) Summary: When a machine using multiple circuit boards has a fault, you can first check whether there is a problem with the internal plug array. Cleaning can sometimes get twice the result with half the effort if you are unsure. Other problems: In fact, most player failures can be eliminated by using the above methods. Of course, other problems sometimes occur, such as chip burnout, component failure, etc. But once the chip burns out, it needs to be used special equipment Replace the chip, and then you must ask the maintenance department for help. Europoint Thomson Consumer Electronics has approved Software patents Of the countries that control the licensing of MPEG -/2 Layer 3 patents, these countries include the United States and Japan, and EU countries are not included. Thomson actively strengthened the protection of these patents. Thomson has been European Patent Office Grant software patents, but it is not clear whether they will be Judicial Office strengthen. See software patents in the European Patent Agreement. about Euclidean point Thomson Patent documents Please refer to their websites for the latest information on the license agreements and fees. In September 1998, Fraunhofer Institute sent several MP3 players software development The person sent a letter stating "publish or sell encoder or decoder ”Authorization is required. This letter claims that unauthorized products "violate Fraunhofer's and Thomson's patent right 。 To manufacture, sell or release products that use the [MPEG Layer-3] standard or our patents, you need to obtain license agreements for these patents from us. " These patent problems have greatly slowed down the development of unauthorized MP3 software and led people to turn their attention to developing and welcoming other products such as WMA and Ogg Vorbis In this way succedaneum 。 Manufacturer of Windows development system Microsoft Company from MP3 Specific Their own Windows Media Format to avoid licensing issues related to patents. Unauthorized encoder And players seem illegal in countries where software patents are recognized. Despite these patent restrictions, the eternal MP3 format continues to move forward; This phenomenon seems to be caused by the following factors Network effect : * I am familiar with this format, but I do not know that there are other optional formats. * These optional formats do not generally and obviously surpass the advantages of MP3. * A large number of music in MP3 format, * a large number of different software and hardware using this format, * No DRM Protection technology This allows MP3 files to be easily modified, copied and republished through the network. * Most home users do not know or care about software patent disputes, which are usually irrelevant to their personal use and use of MP3 format. In addition, patent holders are unwilling to strengthen the collection of licensing fees for open source decoders, which has also brought about the development of many free MP3 decoders. In addition, although they tried to prevent the release of encoder Binary code Thomson has announced that individual users who use free MP3 encoders will not have to pay for them. although Patent fee This is a problem that many companies need to consider when they plan to use the MP3 format. It has no impact on users, which brings about the popularity of this format. Sisvel S.p.A. and its US subsidiary Audio MPEG, Inc. Previously infringed MP3 Technical patents Thomson was sued on the grounds of, but those disputes were finally settled in November 2005 Sisvel It ended with the authorization of Thomson MP3. Motorola signed an MP3 authorization agreement with Audio MPEG. Since Thomson and Sisvel both have their claims Codec The legal status of MP3 patents is not clear. Fraunhofer's patent expired in April 2010, and MP3 algorithm is not subject to patent protection 。 
