MP3 adopts audio compression technology, which compresses sound into files with smaller capacity with the compression ratio of1:1even 1: 12, and can maintain good sound quality. Because the full name of this compression method is MPEG 1 (MPEG 1: Moving Picture Experts Group) Audio Layer -3, people call it MP3 for short. Music stored in MP3 form is called MP3 music, and devices that can play MP3 music are called MP3 players.
MP3 is the most popular music format on the Internet, which originated from the digital transmission scheme of147 of a German company in 1987. It adopts the technology of MPEGAODIOLayer 3, and compresses the sound file into a music file with a compression ratio of about 1∶ 12, which makes the transmission and storage more convenient and more conducive to online listening or downloading by netizens. At the same time, the popularity of MP3 format music has also led to the emergence of MP3 dedicated playback equipment, which has developed rapidly in recent years. At present, the popular MP3 devices in the market have gone far beyond the original "player" category in terms of functions and performance, and gradually developed into multimedia handheld devices integrating audio playback (including music formats other than MP3), recording and rereading, text reading, mobile storage, FM radio and other functions. Some high-end MP3 devices even integrate audio editing, movie playing and other functions.
MP3 has many advantages, mainly including three points: First, it greatly reduces the file size, so it can store more information in the same space; Second, because there are no mechanical parts, all of them are electronic parts, so there is no vibration problem, which is more suitable for listening to music during exercise; Third, you can edit your favorite songs at will. There are advantages and disadvantages, and MP3 also has some disadvantages. MP3 audio compression technology is a kind of distortion compression, because the human ear can only hear the sound of a certain frequency band, and other sounds with higher or lower frequencies are useless to the human ear, so MP3 technology removes this part of the sound, thus greatly reducing the file size. Although it sounds like MP3 music still has a sound quality close to that of CD, it is a little worse than CD.
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MP4
The current MP4 market is too chaotic, and there is no unified standard statement for industry and technology.
Simply put, MP4 is the next generation of MP3, which can play MPEG-4. MP4 players mostly use hard disk or flash memory as storage media, which not only has the basic functions of traditional MP3, such as playing audio files in different formats such as MP3 and WMA, recording and FM radio, but also can play video files in MPEG-4 format. In addition, MP4 will have its own LCD screen, which can be connected with computers or other digital devices through USB/OTG to meet the demand of watching movies anytime and anywhere. In addition, some MP4 products also have the functions of digital camera, digital video camera and digital storage companion. The exact concept of MP4 is a long story, because the brand, market, product specifications and configuration standards of MP4 can all be described in one word-"chaos". I don't know if it's hype or fashion. Now, in the eyes of merchants, players that can touch a little video are all called MP4. Consumers are also confused about the promotion of manufacturers. Industry-recognized definition: MP4 player is a player that can support MPEG-4 standard video format files, and at the same time can support color screens with different resolutions from 1.8 to1280x1024.
Technically speaking, MP4 uses MPEG-2 AAC technology, abbreviated as A2B or AAC technology. Its characteristics are more perfect sound quality and higher compression ratio (15: 1-20: 1). MPEG-2 AAC can provide high-quality audio coding with optional range of 1 ~ 48 channels when the sampling frequency is 8 ~ 96 kHz. AAC is the abbreviation of advanced audio coding, which is suitable for the coding of multi-channel ultra-high quality audio signals from the telephone voice quality with a bit rate of 8kbps to 160kbps, and allows multimedia coding and decoding. Some functions that MP3 does not have are added, such as the perfect reproduction of stereo, the scanning of effect sound of bit stream, multimedia control, noise reduction, etc., so that the sound quality of CD can be perfectly reproduced after audio compression.
In fact, MP4 cannot be literally understood as MPEG-4 or MPEG- 1 Layer 4 format. The origin of MP4 name is not directly related to its own technical meaning, otherwise it should be called MPEG-2 AAC. The real meaning of MP4 comes from the copyright issue. For record companies, the defect of MP3 is that it ignores the copyright treatment that authors and publishers should enjoy. Therefore, GMO(Global music one) Company proposed a solution based on AT&; AAC authorized by T Company improved the audio compression method and application of ——A2B and named it MP4. Its intention is probably to explain that MP4 is an upgrade technology after MP3, which just fits people's habitual thinking. A2B technology mainly consists of the following three parts. First, at & amp； T's audio compression technology patent can improve AAC compression ratio to 20:1without losing sound quality; Second, secure database, which can create a specific key for your A2B music file and put this key into its database, only A2B players can play music with this key; Third, protocol authentication, including copy permission, allowed copy quantity, total song duration, song playable time, business sales permission and other information. Therefore, MP4 is a commodity, which uses the improved MPEG-2 AAC technology to compress audio, and joins the intellectual property agreement directly authorized by the publishing company to form a new form of digital music standard.
MP4 technology is far superior to MP3 technology, because it is more suitable for the development of multimedia technology and the needs of audio-visual appreciation. It is unique in that it adopts the improved MPEG-2 AAC technology and the intellectual property agreement directly authorized by the publishing company as the new standard, and its compression ratio is higher than MP3, but its sound quality is better than MP3. From the perspective of copyright protection, it is welcomed by the publishing industry. Moreover, the screen is relatively large, which not only provides a good display effect, but also expands some popular and practical functions, such as e-books, browsing pictures and so on. However, battery life and high cost are the current shortcomings of MP4.
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MP5
The definition of MP4 is ambiguous, and the name of MP5 has no basis. Since 2006, the "product" of MP5 has appeared in the market, which was only a kind of market hype in the industry.
At first, some merchants saw that MP4 mobile phones were selling well, so they added a huge speaker, which not only beautified the appearance, but also hyped the concept. MP5 mobile phone with external speakers has one more media device than MP4 mobile phone. No matter what the name of MP4 mobile phone is, MP5+MP4+ is a media device, which makes the end users feel reasonable. But the relevant practitioners can't accept this term.
At the 12 international integrated circuit conference and exhibition (IIC 2007, China), a handheld device MP5 appeared. Patriot exhibited this P88 1 MP5, which was officially named MP5 because it solved a technical bottleneck of MP4: it supported streaming media formats of real companies such as rm/rmvb. The breakthrough of this technical bottleneck is attributed to Freescale's i.MX3 1 product. 1. The MX3 1 processor is based on the ARM 1 1 platform and adopts Freescale intelligent speed-up technology, which can maximize the effective cycle/instruction (eCPI) and set a new benchmark for mobile entertainment solutions with low power consumption/performance ratio. The processor supports MPEG-4 and H.263 codec, its CPU is 266MHZ, and the system is 133MHZ. It provides 16/ 18 color LCD controller and supports VGA. Real's rm/rmvb and other streaming media formats have the advantages of small size, high definition and rich film sources. However, for a long time, supporting real format playback has been the technical bottleneck of portable media players. Under the platform of i.MX3 1, P88 1 finally achieved this breakthrough. Patriot MP5 P88 1 has a 4.3-inch high-resolution screen, which can support up to 720×480 resolution and 16∶9 widescreen display.
After the IIC 2007 exhibition in China, I believe the relevant practitioners have accepted the term-MP5. Industry and technology will be in the fuzzy definition stage of MP4 and MP5 for a long time.
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MP6
This is the first Rise processor, and it is also a Socket 7 CPU specially designed for notebook computers. Because of this, the calorific value of this product is very low. The main cache of the CPU is 16KB (8KB for instructions and 8KB for data), and its auxiliary cache is located on the motherboard. The size of the secondary cache varies from 5 12KB to 2MB, and its speed is synchronized with the system bus frequency. MMX instruction is supported, and the clock frequency is between 166-366MHz.
Chiwei MP6 perfectly guarantees the processing speed with the highest frequency of 500MHZ in the industry, including all the mainstream multimedia formats at present. This product directly supports the most common video resource RM/RMVB format, FLV format and video coding AVI/XVI/DIVX/MPG/MPEG-4 format.
[Video playback performance parameters]
RM/RMVB pixel 160 * 128 ~ 800 * 600
The maximum frame rate of RM/RMVB is 30 frames.
RM/RMVB code rate is not limited.
The maximum pixel is 640*480.
Frame rate 25 frames @640*480
Code rate unlimited
Supported video coding RM/RMVB/FLV/AVI/MPEG4/MPG/DAT
Chi used an independent audio codec for MP6, supported lossless compression of FLAC and APE audio, and provided two famous sound effects, BBE and SRS surround sound, which perfectly presented a CD-level sound quality experience for users.
Audio playback performance
The Mp3 encoding rate/sampling rate is 8 ~ 320kbps/8 ~ 48khz.
WMA coding rate/sampling rate 12 ~ 320kbps/8 ~ 48khz.
APE coding rate/sampling rate is not limited to /8 ~ 48 khz.
FLAC coding rate/sampling rate is not limited to /44 100hz.
16 million color 3.0-inch LTPS color screen, excellent energy consumption and durability, while the horizontal and vertical viewing angles are greatly improved, reaching about 170 degrees, with shorter response time and higher display brightness. The resolution is as high as 960×240; The playback speed is as high as 30 frames per second.
Note: MP5 and MP6 are hype.
Source: Chengdu Business Daily, March 28th, 2008 14: 2 1: 58.
"I went to the computer city to buy a digital walkman. Merchants told me that MP5 and MP6 are better than MP4 and can play more video files, but the price is more expensive than the traditional MP4 player, isn't it? " Recently, a reader of Ms. Xie in Chengdu sent an email to this newspaper, saying that after visiting the computer city, she found that the market was a bit chaotic, "there is no unified standard for prices and product specifications."
As we all know, familiar names such as MP3 and MP4 have long been deeply rooted in people's hearts and become the floorboard of portable audio-visual products. "In fact, the two new terms' MP5' and' MP6' appeared against the background that the selling points of' MP3' and' MP4' products have been exhausted recently, which has created the illusion that the walkman products are being upgraded and is suspected of fooling consumers." A digital industry veteran told reporters that only MP3 and MP4 are technical terms at present. For example, MP3 is an audio file compression format and MP4 is a video file compression format. "There is no inheritance between these names, and it is easy to think of products that can play MP3 and MP4 files after people are founded."
It is said that the so-called "MP5" and "MP6" are all hyped up by manufacturers, in which "MP5" represents the addition of digital TV playback function or RMVB function on the basis of MP4, and there is no real leap in video playback quality and technology like MP3 and MP4, and some domestic manufacturers are full of so-called "MP5" products with relatively low-end analog TV playback function. "MP6" is the product series name launched by a domestic digital brand. It uses terms related to MP3 and MP4 to raise the attention of products and attract consumers' attention, but it has not greatly improved its functions.