区块链中什么是核心技术,区块链中什么是碰撞性

❶What is DAC

The DAC format is the abbreviation of Digital Audio Compress in English. It is a product of Beijing Haojie Zongheng Network Technology Co., Ltd. (famous for the successful development of Super Jieba). With its own Audio coding technology accumulated over many years, original natural acoustic model, professional-grade audio compression format developed, ultra-high sound quality, and good positioning capabilities.

Traditional audio compression technology is based on the human hearing model. This theory is based on the fact that near a certain frequency, loud sounds overpower small sounds, so small sounds can be deleted; such as a loud bang It will make you unable to hear other sounds. In fact, people cannot hear small sounds, but they can distinguish the small sounds if they listen carefully. Therefore, DAC created its own natural acoustic model to ensure the resolution of all sounds.

The DAC format has the following characteristics: supports the same level of high-quality audio compression algorithms as AC-3 and DTS; supports frequencies from 22K-1M; supports channel numbers from 1 to 32 channels, including 5.1 and 7.1; Supports 16-bit to 32-bit; each channel is independently encoded, without interference or crosstalk problems; the bit rate of each channel is 75, 100, 120, 150Kbps, etc.;

Computing efficiency: using 100MHZ PDA, completely It can decode and play high-quality music above 44KHZ in real time, and the CPU takes up about 50%.

The DAC format has the following advantages: at low bit rates, the size of DAC compression is similar to MP3, but the sound is not gritty and the sense of positioning is still there. Compared with the original lossless compression, only the sound above the cutoff frequency will be found. There are some small differences in the sound; at medium bit rates, the DAC sound quality is similar to that of AC-3, and the cutoff frequency exceeds the range of the human ear, which can be measured from the instrument; at high bit rates, the difference between DAC sound quality and CD is almost indistinguishable to the human ear. , the difference can only be distinguished by comparing the waveforms in the instrument; the efficiency of the DAC will never be dull, because it does not delete the frequency, it does not think that the human ear cannot hear it; it will not be dull, because it does not target Low quality audio is processed.

·The determination of standards must be determined by market applications

In digital homes, DAC can be used to build high-quality cinema-level digital sound systems and their processing. Due to its high computing efficiency and low CPU usage, DAC can also support the real-time transmission and encoding and decoding requirements of high-quality audio on the Internet. The launch of the DAC format of Hero Company has filled the domestic gap, saved foreign exchange funds, and its role in promoting my country's audio industry cannot be underestimated.

The promotion goal of the DAC format is to gradually make DAC one of the market standards for audio coding. "There is no road in the world. If there are more people walking on it, it will become a road." The same is true for standards. Only when more people use them can they become standards. Market application is the key to testing the success of standards. The standard is not unique, just soundIn terms of frequency encoding, MP3 and WMA can both be called market standards. There is also competition between standards. WMA is on the rise, while MP3 is on the decline. The Chinese DAC format will participate in this competition.

First promote DAC decoders, and then promote DAC encoding technology. Hero Super Jieba is the first decoding software to support the latest DAC format. Hero Super Jieba has more than 50 million users in China and is also very well-known in the international market. The promotion of Hero Super Jieba in PC systems and embedded systems is one of the important conditions for the promotion of DAC format. In January 2005, the new product launch of Hero Super Jieba 9 will fully support the DAC format, allowing users to personally experience the shocking feeling of China's own audio format, which will greatly promote the promotion of the DAC format.

Bundled with video formats for joint promotion. In order to get rid of the DVD technology monopoly of foreign companies, relevant government departments in our country strongly support the research and development of next-generation DVD technology and organize the formulation of new technical standards. Many professional companies are also working hard in this regard. Against this background, the standard disputes for EVD, HDV, and HVD emerged in 2004. However, these three companies only focus on the research and development of video technology, but do not yet have commendable core technologies in audio. The launch of the DAC format is of great significance to strengthening my country's next-generation DVD standards. At present, Haojie Company has reached a cooperation agreement with HDV Company and is preparing to jointly promote its own audio and video standards in the industry.

Key breakthroughs will spur downstream companies to follow up. MP3 charges high licensing fees, which not only increases the burden on domestic companies, but also causes greater damage to large foreign audio companies. Haojie Company will promote its DAC format to large domestic audiovisual and communication companies and international multinational companies, provide them with more discounts, and promote the rapid promotion of the DAC format.

Establish a DAC alliance to provide good technical services for enterprises to support DAC. Imhero www.imhero.com entertainment platform and JMA digital copyright protection system provide security guarantee for the release of DAC format and maximize the rights and interests of content providers. As content, software, chip and other manufacturers support DAC, an industry chain surrounding DAC will eventually be formed.

❷ What is a DAC

DAC (digital-to-analog converter, also called a decoder) refers to a digital-to-analog (D) converter that converts on/off pulse signals into analog sound signals. /A) converter. DACs are already installed in CD players, but external DACs can upgrade the sound quality of CD players or other digital players. ■ D/A converter: A device that converts digital audio signals into analog audio signals in digital audio products (such as CDs and DVDs). D/A converters can be made into independent machines for use with CD turntables, and are often called decoders. I usually talk about decoders simply: A decoder is actually a conversion tool. The main purpose of using decoders on the market is to convert digital signals (Such as optical fiber, coaxial) into analog signals (such as the channel output on the sound card), a pure decoder needs to cooperate with digital input to work. Of course, some decoders have analog output of sound cards such as USB, but that is another matter. An operational amplifier is an "operational amplifier". An operational amplifier is a very widely used linear integrated circuit. And there are many types. In terms of application, it can not only amplify weak signals, but also be used as an inverter and voltage follower. It can add and subtract electrical signals, so it is called an operational amplifier. Not only is it widely used in other places, it is also used most in audio. For example, in addition to some discrete components and tubes used in preamplifiers, buffers, and headphone amplifiers, most of them use integrated operational amplifiers. Sometimes it is also used in voltage stabilizing circuits to produce high-precision voltage stabilizing filter circuits. Due to their different internal structures, various op amps produce different distortion components, so their timbre characteristics also have certain differences. Originally, what we were pursuing was high fidelity. The op amp should have the lowest distortion, be able to truly restore the music, and be best without personality. However, due to the need to cooperate with other audio components such as digital audio sources, power amplifier tubes, etc., if it is too dry or cold, it can be matched with an op amp with a delicate and warm tone, while if it is too feminine or soft, it can be matched with a colder, brighter tone. The operational amplifier can cooperate with the whole machine to achieve the best effect by learning from each other's strengths. Therefore, it does not mean that the more expensive the op amp is, the better the effect will be. The matching is very important, and the best in terms of listening is the goal. If it is used in a low-voltage analog filter circuit, it is also necessary to choose a type of op amp with good low-voltage operating performance.