First, the present cinema projection equipment is divided into film type and digital type. Looking at the development trend in the future, digital movies are definitely in the ascendant.
2. The projectors used in cinemas are definitely not 1080p projectors for household use, but professional digital movie projectors. Now the major brands involved are NEC SONY, Video DP Barco and so on. These brands are also used in relatively low-end occasions. High-end digital cinema projectors have very high brightness, generally more than 10,000 lumens, even up to 30,000 lumens. At the lower end, there are more than 5000 lumens, while the brightness of the ordinary commercial education projector is only about 2000 lumens.
3. Chips are also different. Many digital projectors using DLP technology are 3D MD chips. 3LCD chips are basically difficult, because the bulb temperature is very high, which may melt the LCD panel. The price of a 3D MD chip is very, very expensive.
4. Resolution is very particular. The resolution of digital movies can be divided into 4K, 2k, 1.3k and 0.8k from high to low.
Difference: 4K (digital machine resolution 4096 *2016 825 million pixels) is the highest end. And 4K movies can be synchronized, 2K movies have. The 4K device can only see the difference between 2K and 2K on the screen which is more than 20 meters wide. 2K (digital machine resolution 2048 *1080 221 megapixels) is an international standard machine. 1.3K (digital machine resolution 1280 *1024.131 million pixels) is the national standard machine. 0.8K (digital machine resolution 1024 *768.786 million pixels) is a rural projector. 1.3k digital projector features: 1.3K standard is the domestic standard. 2K is an international standard. Difference: 1.3k domestic movies are basically synchronized, while 2K imported movies including Hong Kong movies (co-production counts domestic) can be distributed to large-scale films. Film global synchronization (as long as the country introduces) 1.3K imported films, sub-accounts can not be put, buy fragments can be put. Can not put the sub-account, because of copyright, chip-level hardware constraints.
Now Hollywood's demand for cinemas is 2K. Although 4K projectors and even 8K chips are available, few 4K film sources are available.
5. Contrast is not very high. Now the contrast of 1080p projectors at home has reached 1 million:1. The contrast of 1080p projectors at low-end entry level is also everywhere, but the contrast of digital projectors is much lower. The contrast of 2000:1 is also very common.
Sixth, in the whole digital film projection link, the projector is only one of the components, as well as servers and other equipment, a digital movie also has more than 500G bar should.
The above information is rarely disclosed, and ordinary people know little, I can not be all right, but more than 90% should be no problem.
Cinema Audio System
Since Dolby's film stereo was introduced into China in 1995, the domestic film stereo industry has made great progress, especially the development of digital film, which has greatly promoted the progress of film science and technology in China. Nowadays, most of the city cinemas in our country have been transformed into SR stereo or digital stereo cinemas. The improvement of cinema acoustic surroundings and the improvement of sound system quality have been paid more and more attention. Cinema acoustics system covers a wide range of areas. It includes architectural acoustics design and all sound-return systems and their designs in cinemas. This paper only discusses the basic characteristics of the B-ring part of the film sound-returning system, power amplifier and loudspeaker, and the design method of sound field. At the same time, it introduces the stereo power amplifier and loudspeaker used in cinemas in China at present.
1. Basic Technical Characteristics of Power Amplifier
The function of power amplifier is to amplify the decoded and balanced audio signals and to promote the sound supply of loudspeakers. In stereo film playback technology, the requirement of power amplifier is high efficiency, low distortion, high power and high fidelity. It ensures that the sound playback has enough power and can truthfully reflect the sound quality and timbre of audio signal. To master the technical performance of power amplifier is the necessary condition for the correct selection and use of power amplifier, and the frequency response and distortion should also be considered.
2. Frequency response
Frequency response should consider two indicators: gain-frequency response and distortion-frequency response.
Gain-frequency response refers to the amplification ability of each frequency component of power amplifier. It shows the frequency characteristics of the power amplifier, that is, the bandwidth of the amplifier and the non-uniformity of the magnification in the bandwidth. Although the audible acoustic response ranges from 20 kHz to 20 kHz, in order to reduce distortion, the bandwidth of the amplifier is extended to 10 kHz to 100 kHz, and the non-uniformity is less than 1 dB.
3. Distortion
Distortion refers to the non-linear distortion of power amplifier. Considering static index, harmonic distortion, crossover distortion, clipping distortion, phase distortion and intermodulation distortion, dynamic index has transient intermodulation distortion and so on. For transistor power amplifiers, only a considerable amount of negative feedback is added to achieve a fairly high level of harmonic distortion (currently it can be reduced to less than 0.01%). However, even if the harmonic distortion is very small, the sound stiffness and high frequency hair are still felt in the subjective hearing, which is not as good as the quality of the tube power amplifier which is two grades lower than it. This is because the over-load distortion of the transistor power amplifier is hard. As shown in Figure 3, after the over-load point, the non-linear distortion increases rapidly, and the output waveform is cut like a knife. The over-load curve of the transistor power amplifier is relatively flat, but the output waveform distortion is still radian. Because there are many impulse components in modern music, in order to obtain good sound quality, transistor power amplifier should have larger output power. Usually, its output power is at least two times larger than that of electron tube power amplifier.
Need to buy cinema equipment, you can contact Guangzhou Fubang Culture Technology Co., Ltd. (Guangzhou Fubang Audio and Video Division). We provide professional public welfare film equipment, installation, commissioning, after-sales step in place. Contact number: 400 166 2959
400-166-2959
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