Analysis:
Technically speaking, MP4 uses MPEG-2AAC technology, abbreviated as A2B or AAC technology. Its characteristics are more perfect sound quality and higher compression ratio (15: 1-20: 1). MPEG-2AAC 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 AdvancedAudioCoding, which is suitable for the coding of multi-channel ultra-high quality audio signals from telephone voice quality mono with bit rate of 8kbps to 160kbps, and allows multimedia coding and decoding. It adds some functions that MP3 does not have, such as perfect stereo reproduction, bit stream effect sound scanning, multimedia control, noise reduction, etc., so that the sound quality of CD can be perfectly reproduced after audio compression.
MP4 cannot be literally understood as MPEG-4 or MPEG- 1Layer4 format. The origin of MP4 is not directly related to its technical meaning, otherwise it should be called MPEG-2AAC. 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(Globalmusicone) Company proposed a method based on AT & amp； 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-2AAC 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.
Advantages and Prospects of MP4
The superiority of MP4 technology is far superior to that of MP3, because it is more suitable for the development of multimedia technology and the needs of audio-visual appreciation. Its special feature is to use the improved MPEG-2AAC technology and the intellectual property agreement directly authorized by the publishing company as the new standard. MP4 is specially designed for encryption and authorization, and it has the following characteristics:
(1) Every MP4 music is an executable file with an extension of exe. Its embedded player is easy to operate and it is very convenient to double-click in Windows.
(2) Due to the advanced A2B audio compression technology, the MP4 file size is only about three-quarters of that of MP3, with better sound quality and higher compression ratio. From this point of view, MP4 is more suitable to spread on Inter with better sound quality.
(3) Unique digital watermarking, MP4 adopts the digital watermarking technology named "SOLANA", which can easily track and find piracy, and any illegal decompression of MP4 may lead to the destruction of MP4 original files;
(4) Support copyright protection. MP4 music has built-in copyright descriptions including words and images related to the copyright owner, which can explain copyright and show respect for composers and singers (performers);
(5) The function is perfect. MP4 can independently adjust the volume of the left and right channels, and has built-in waveform/frequency division dynamic audio display and music manager, which can support a variety of color pictures, website links and infinite scrolling text.
Although MP4 has many advanced advantages, it still needs time to test in the process of competing with MP3. The key reason is that there are no restrictions on the use of MP3, which is vividly reflected on the Internet. On the contrary, although AAC technology is open, MP4 itself is protected by strict patents and licenses. Undoubtedly, this definitely makes the application scope of MP4 very narrow. In addition, audio formats, encoders, players, etc. With the application of AAC technology in the network, due to the final file format, it is difficult to be compatible with each other in a short time, which greatly increases the difficulty of popularizing MP4.
MP4 has its unique advantages, the compression technology is better than MP3, and the sound quality is better than MP3. From the perspective of copyright protection, it is welcomed by the publishing industry. But MP3 is the most popular music format at present, which occupies a lot of network resources and is deeply loved by music lovers. MP3 is simple and flexible to use, and there is even a "Walkman" product that can freely choose MP3 tracks. The popularization of GMOMP4 will encounter great difficulties. Especially the AAC format which is the same as A2B compression technology, its codec and music have appeared on the network, which may be more easily accepted and developed by the public.
It seems that MP4 is very good, but it is designed to compete with lawless and copyright-free MP3. Although it is welcomed by many people who respect copyright, it also needs the extensive support and support of the global community in order to get out of the embarrassing situation of "applauding without being a seat". The future of MP4 may be as described in an ancient poem: "It's a long way to go in Xiu Yuan, and I will go up and down." .