The origin of MP4
Compared with the well-known MP3, people don't know much about MP4. Although logically speaking, when we hear or see MP4, we will infer that it is the successor format of MP3, but the fact is much more complicated. In fact, there are too many differences between MP4 and MP3. MP3 is an international standard for audio compression, while MP4 is a brand name. Although both of them belong to the category of online music formats, they also represent two completely different audio compression technologies and formats.
The appearance of MP4 makes it even more difficult to distinguish the MPEG standard series that were easily confused. MP3 is not the MPEG-3 standard, but the abbreviation of MPEG Layer 3, which is an ISO/IEC international standard and a completely open audio compression technology. MP4 is neither the abbreviation of MPEG Layer 4 nor the MPEG-4 standard. It is GMO that adopted A2B music based on MPEG-2AAC (Advanced Audio Coding) authorized by AT&T Company for MP3 that infringed the copyright of music publications, and named it MP4. Its intention is probably to explain that MP4 is an upgrade technology after MP3, which is just in line with people's thinking habits.
A2B technology mainly consists of the following three parts. One is at&t's patent on audio compression technology, with perceptual coding as the key technology, which can improve AAC compression ratio to 20:1without losing sound quality; Secondly, in the secure 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.
Compared with previous music formats such as MP3, MP4 has the following features:
1. Each MP4 music is an executable file with an extension of exe, and its embedded player is easy to operate. It is very convenient to double-click to run and play in Windows.
2. Due to the advanced A2B audio compression technology, the size of MP4 file 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 for online communication with better sound quality.
3. Unique digital watermarking technology 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 of the work, which can explain the copyright and show respect for composers and singers (performers).
5. The functions are relatively complete, MP4 can independently adjust the volume of the left and right channels, and the built-in waveform/frequency division dynamic audio display and music manager can support a variety of color pictures, website links and infinite scrolling text.
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.
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Apple iPod video five generations
Market reference price: 2600 yuan (60GB)
The external dimensions of the fifth generation iPod video are 2.4x4. 1x0.43 inches. Compared with the fourth generation 30GB iPod, the thickness of 30GB video is reduced by nearly 50%, and the total volume is reduced by 45%. Although the iPod video has a large capacity of 60GB, it still achieves the thickness of 1. 1CM, which is the thinnest of hard disk MP4.
IPod video uses a 2.5-inch 65,000-color 320×240 QVGA color LCD screen, supports LED backlight display, and can easily browse pictures, enjoy MPEG4-4 movies and H.264 standard video programs. It can also be equipped with an iPod A/V data cable to project video programs and music picture slides onto the TV. In particular, all the control can be done remotely through the optional iPod Universal Dock. Power supply management has been improved. The 60GB iPod can play audio files continuously for up to 20 hours, and it only takes 4 hours to fully charge, or it can quickly fill 80% in 2 hours.
Innovation Zen Vision W Market Reference Price: 3 199 yuan (30GB)
As an equal opponent with Apple, the research and development strength of innovative new products is still daunting. Its new ZEN Vision W player is a product that competes with Apple's iPod video. In fact, this ZEN Vision W looks more like a real MP4.
The innovative ZEN Vision W uses a 4.3-inch 260,000-color TFT screen with a resolution of 480 x 272. The 30G version of ZEN Vision W has a circumference of 134mm x 75mm x 22mm, which is more fashionable than the ZEN Vision introduced earlier. Innovative ZEN Vision W has a built-in 30GB micro hard disk, and the system adopts Microsoft Portable Media Center. While listening to high-quality music, you can also browse your favorite picture screensavers.
It is also more powerful in function, supporting MPEG- 1, MPEG-2, MPEG-4, WMA, DIXV, XVID, WMV9, and various audio and video formats: MP3, WMA, WAV, PCM, AVI, WMV9, with built-in FM radio and recording functions. It adopts USB2.0 high-speed interface and built-in CF slot, which can be directly connected with CF card and used as a digital companion.
Sharp HD screen with first-class vision: Super Vision M800
Market reference price: 4499 yuan (30GB)
Super Vision M800 is designed in chocolate color, with black as the main color and silver frame. The surface of the fuselage adopts piano paint, 4.3-inch LCD screen, and the thickness of the fuselage is 17MM, which not only brings light and thin volume design, but also shows noble and elegant visual effects.
The most outstanding highlight of Super Vision M800 is that its display screen adopts Sharp's high-definition LCD screen, which adopts widescreen design with a resolution of 480 * 272, 16: 9 and a viewing angle of 170. The effect of video and picture browsing is quite excellent, which can be said to be the top MP4 screen at present. The button design of Super Vision M800 is also very distinctive. In addition to good hand feeling, it is designed by etching process, and pink can be exposed at the touch of a button, which is very beautiful. M800 also provides video adjustment (video width, brightness), subtitle setting (subtitle color, synchronization, display), and automatic recovery function after video interruption. The capture function in video is a major feature of M800, and you can take screenshots of movies at any time.
The video formats supported by Super Vision M800 are AVI, VOB, MPG, ASF, WMV and DAT. Electronic text reading function can be viewed horizontally or vertically, and also supports voice reading function. M800 also has FM radio, digital companion, recording, recording and video recording functions, and the data reading speed is also quite fast, with the reading and writing speed of about 21MB/s. ..
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generally speaking
About 40 GB MP4 3XXX RMB.
About 20 GB 2XXX yuan
100G is unrealistic. It is estimated that it will cost tens of thousands of yuan. Might as well buy a notebook.