Sixth, sound card terminology explains DSP: Digital Signal Processing (Digital Signal Processing). DSP technology has a wide range of applications in analog electronic fields such as tone control, distortion effect, WAH-WAH pedal. At the same time, the DSP can also show up in a variety of effects such as simulation equalization and reverb. DSP operations can be performed through computer CPUs or special DSP chips. Different, dedicated DSP chip processing is more optimized than computer CPU processing, faster. Sampling: The process of simulating audio is converted to digital audio, as sampling, the main device used is analog / digital converter (Analog to Digital Converter, that is, the ADC, and the corresponding number / module converter, ie DAC). The process of sampling actually converts the electrical signal of the usual analog audio signal into binary code 0 and 1, these 0 and 1 constitute a digital audio file. The greater the frequency of the sampling, the more sound quality is guaranteed. Since the sampling frequency must not be more than twice the highest frequency of the recorded, it does not generate distortion, and the human hearing range is 20Hz ~ 20kHz, so the sampling frequency is at least 20K × 2 = 40 kHz, and it can guarantee that there is no low frequency distortion, this It is also the reason why the CD sound quality is 44.1 kHz (slightly higher than 40 kHz is in order to stay). Signal to noise ratio: The maximum fidelity output of the signal calculated by DB and the ratio of inevitable electronic noise. The bigger this value is, the better. Lower than 75dB, the noise is likely to be discovered when it is silent. The signal to noise ratio of the AWE64 Gold sound card is 80dB, which is relatively reasonable. SB LIVE! It is also a top signal to noise ratio of 120 dB. In general, because the high frequency interference in the computer is too large, the signal-to-noise ratio of the sound card is often unsatisfactory. However, SB Live! Provides a digital output SPDIF, which can bypass the analog part of the output, greatly reduced noise and distortion, and greatly improved the dynamic range and sharpness sound card: Sound Card: As the name suggests, Card, which is the same as the vocal tie in the human throat, with it can make a sound, you can communicate, you can sing. The role of sound card in the computer is the same, it can achieve human-machine communication, such as learning foreign language, voice input, etc. The sound card is called a sound card or sound card in the Hong Kong and Taiwan area, which is essential in multimedia computers. The computer has a sound function. Sound cards are essential for computer musicians, because the music used to use it is much better than traditional production methods. The sound card took you into a "colorful" audio world. Let you feel the wonder of nature. Synthesis Technology: Synthesis technology in the sound card has two types, first, FRency mode technology (FRENQUENCY MODTITION); second, Wave Table (wave form) synthesis technology. FM synthesis technology uses the calculated method to show the true sound of the instrument, it does not need a lot of storage capacity to simulate a variety of sounds, its structure is simple, low cost, but its imitation ability is very poor. The English name of the wave form is "Wave Table", which means "Waveform Table" from literal translation. In fact, it is recorded in all the sounds (including each of the sounds, tones) that can be made by various real instruments, stored as a wave form file. When playing, according to the MIDI file record, the track is issued to the wavelert, and the corresponding sound information is found from the wave library, after the synthesis, and then play back. Since it uses the sample of real musical instruments, the effect is naturally better than FM. The instrument sound information of the general wave form is recorded in the accuracy of 44.1 kHz, 16bit to achieve the most authentic playback effect. "Soft" wavefringforming technology: It is the form of software (Wave Table in the sound card is stored in the hard disk, and the CPU is called forward) instead of WAVE TABLE.
DLS: Download Source Module It is a technology used by a new PCI sound card. It puts the wave form on the hard disk, and needs to be transferred to memory. But it has a certain difference from Wave Table, DLS is dedicated The PCI sound card of the chip is to achieve music synthesis, while soft wave table technology is to achieve music synthesis through the CPU. Sound Font: is the sound library technology used by Singapore's innovation company in the mid-range sound card. It is in line with characters, and a Sound Fond exhibits a set of music symbols. When you use the MIDI keyboard, you will automatically write down the MIDI parameters, and finally look up in Sound Fond. When you need it, download it to the sound card. It has a biggest advantage that it does not affect the quality of sound due to insufficient storage capacity of the sound card, which can achieve the ideal environment of full tone and tone. This way is now available on the high-grade sound card. Of course, there are two reasons. In addition to this sound library of innovation, it is Microsoft's DLS standard. In contrast, Sound Font technology is prominent, but only innovative sound card can be used, Microsoft's DLS is used in the PCI sound card. Wave table upgrade subcard: You can upgrade the FM sound card to Wave Table sound card. But the original sound card must have an upgrade interface. Since the memory supported by various sound cards and the memory supported on the sound card is different, the price difference is very large. For friends who use FM sound cards, the wave form upgrade sub-card is a very good choice. But it also has a performance / price ratio issue, whether it is worthy of payment. Sampling bits: sample value or sampling value. It is a parameter used to measure the change of sound fluctuations, that is, the resolution of the sound card. The larger the value, the higher the resolution, the stronger the ability to sound. The position of the sound card is the number of binary positions that the sound card used digital sound signals used when collecting and playing sound files. The position of the sound card objectively reflects the accuracy of the digital sound signal to the input sound signal. It is possible to use 16-bit sound card in multimedia computers because people's ear is less than 16 in the resolution of sound accuracy. Sampling frequency: The number of sampling is obtained, and the number of sound samples is obtained per second. The higher the sampling frequency, the better the sound of the sound, but it accounts for more memory. Because the resolution of the people is very limited, Too high frequency does not distinguish it. The sampling frequency is generally divided into 22.05kHz, 44.1kHz, 48kHz three grades, 22.05 can only reach the sound quality of FM broadcast, 44.1KHz is the theoretical CD sound quality boundaries, 48kHz is more accurate. For sampling frequencies higher than 48kHz, the ear has not been distinguished, so there is not much value on the computer. DAC: The computer does not directly process this signal, first transform it into a digital signal that the computer can recognize, and use the DAC (Digital / Analog Transformation) in the sound card, which converts the sound signal into a digital signal, points Two steps, sampling and conversion. Source: It is the source of sound from the literally meaning, that is, where the sound comes from. It mainly exactly accurate sounds accurately. Divided into two forms, external, it is not subject to sound card, the quality of the sound can be stored well, but the cost requirements are high. Built-in, also known as audio card. Sound source card: Itself with a source of music itself but must be attached to a hard disk used on the sound card. With a sound card with a Wave Blaster plug on your computer, you can use the audio card. The requirements of the source card card are very low. When it is set, the interrupt is not occupied, and the address will not reselect, nor without the driver, simply set the MIDI's port to SB MIDI OUT.
Polyphone: This donor is not "consonant" in English, refers to the number of sounds that can make sounds in the same time. If you put a MIDI music, it must Less than or equal to the number of revolutions of the sound card you use, you can hear the best results. So your sound card has the number of repunies, you will be able to hear a lot of wonderful music. But you will spend more money. MP3: It is compressed to a small file to be stored on the disc in a proportion of the sound file in 1 to 10. We usually listen to a VCD a plate of only 120, but a disc processed by MP3 files. It is not a problem, which is not a problem, which is better for computer music, but MIDI (Musical Indtrumend Digital Interfoce music device digital interface): It is not a music signal, the recorded sound must be played Set through the MIDI interface. It is the standard of electronic synthesizer and digital music, and is also a bridge between computers and electronic instruments. It is a good choice for computer music enthusiasts. WAV: In Windows, store the sound file to the extension of the hard disk is WAV. WAV records the sound itself, so it is very hard in the hard disk space. For example: 16-bit 44.1 kHz stereo sounds take up approximately 10MB of capacity for one minute, and it is very far from MIDI. In this way, the compression function of the sound card is equally important. WOC: It is a storage form of a sound file. As long as the extension of the file named VOC is played under the DOS system. It is simplified with WAV, and the core part has no fundamental difference. This form is to first pass the digitized signal after digital / analog conversion, sent by the amplifier to the speaker. AVI: (Audio-Video Interactive) audio video interaction, it is an audio, video signal compression standard introduced by Microsoft. Mono: mono is a comparative original sound replication form, and the early sound card is more common. When two speakers play back the single channel information, we can clearly feel that the sound is passed from the middle of the two speakers to our ear. This lack of location is very backward, but it is already very advanced when the sound card has just started. 3D stereo system: It is our usual three-dimensional. From three aspects to enhance the sound of the sound card, the first: the sound of the sound we hear, second; sound displacement; third, the impact. Whether it is in my own home, or in the cinema, no matter whether it puts VCD or DVD, two channels will appear on the screen, let you choose "Left" "right channel", we have to put it all The selection, the sound of the two channels is mixed together, it sounds a shocking feeling. But it doesn't have a 3D surrounded by a stereo system. 3D surrounded by three-dimensional system: from the 1980s, there are more than a dozen 3D systems In use. To now there are two technologies to use on multimedia computers, that is, SPACE equalizer and SRS (Sound Retrieval System) sound correction system. Let's talk about Space: It uses sound effects and masticinal principles, according to The people's auricle has different inductions, and does not increase the sound, it gives 3D effects, people feel the sound from all parties; SRS: It is completely used in the principle of the euro, the sense of sound of the human ear, Double-channel stereo signal processing, although the sound comes from front, people mistakenly think that it is from all directions. This kind of system can use two ordinary sounds, you can have the shocking effect of the concert hall, it does not cost Therefore, it is very attractive. Accident sound: The basic concept of the acoustic sound card is to use a mono when recording the sound, and the play is sometimes stereo, sometimes mono. Sound cards using this technology have also been in the market for a while, but now they have already hidden.
Survey: four pronunciations are specified in the four channels: the front left, front right, the left, and the right, the audience is surrounded by this. At the same time, a low sound speaker can also be added to enhance playback processing on low frequency signals (4.1 channel speaker system). In terms of overall effects, the four-channel system can bring a sound from multiple different directions to the audience, which can get a sense of auditory feelings in various different environment, giving users a new experience. Today, the four-channel technology has been widely integrated into the design of all kinds of high-end sound cards, and become the mainstream trend of future development. 5.1 Sound: Some relatively well-known sound recording compressed formats, such as Dolby AC-3 (DOLBY DIGITAL), DTS, etc. are technique in 5.1 sound systems. In fact, 5.1 sound system comes from 4.1 surround, there is different in that it increases a central unit. This centering unit is responsible for transmitting a sound signal below 80 Hz. It is conducive to strengthening the vocals when appreciating the movie, focusing on the middle of the entire sound field to increase the overall effect. Du Bunding Logic: Dolby Pro-logic is developed by the Dolby Laboratory of the United States. It is used to restore the sound. It has a big feature, which is the four channels (around front and back) The original sound is encoded, and it forms a double-channel signal, and then the amplifier will be re-supplied to the amplifier when the sound is released, so that the surrounding stereo effect is surrounded by the intermediate link, so that the previous planar sound field is changed. DDP circuit: DDP (Double Detect and Protect: Double Detection and Protection), which allows Space to no longer processes the input signal, while detecting the frequency and direction of the sound, and automatically adjusts to obtain the best effect. DSP (Digtal Signal Processor: Digital Signal Processor): It is a dedicated digital signal processor that has "exhibits a style" on the high-end 16-bit sound card. The high-grade sound card has achieved unsounoted merits. However, with the continuous development of new technology, the contradiction between DSP is getting more and more prominent, and the sound card merchants have to "reluctantly cut love" for their own interests. Hz Hertz: The unit used to describe the sound vibration frequency, also known as a vibration cycle per second, called 1 Hz, and the audio hearing of the human ear is about 20 Hz to 20 kHz. Encoding and decoding: In digital audio technology, use the number size instead of the sound high and low analog voltage, and the process of compressing the audio data is called encoding; when playing music, the compressed data is restored, referred to as decoding . SNR: Signal to Noise Ratio: It is an important indicator for judging the noise of sound card noise. The ratio of the power of the signal and the noise signal is SNR, and the unit decibels. The better the SNR value, the better the filter effect of the sound card, which is generally greater than 80 decibels. Frequency Response (Fr: Frequency Response): It is an evaluation criteria for the ADC and AC converter frequency response capabilities for sound cards. The received range of people's ear to the sound is 20 Hz-20kHz, so the sound card is always maintained as a linear response effect in this range. If the protrusions (in the sound card data are represented by power gain) or decline (with power attenuation) is a distortion performance. Total harmonic distortion (THD N: Total Harmonic Distortion Noise): THS N is the sound card The evaluation index of fidelity. It compares the degree of matching the signal input by the sound card and the extent of the waveform of the output signal. The lower the value, the smaller the distortion. " N" in this formula indicates that noise is considered while considering fidelity.
Direct Sound 3D: Old Audio API from Microsoft DirectX. It works to help developers define the positioning and sound of the sound in 3D space, then hand it over to the DS3D compatible sound card, allowing them to implement in various algorithms. The effect of positioning sound actually depends on the algorithm used by the sound card. For sound cards that cannot support DS3D, its role is a three-dimensional sound-effective HRTF algorithm that needs to occupy the CPU, so that these early products have the ability to handle three-dimensional sound. But you can't be satisfactory from actual effects and implementation efficiency. Therefore, thereafter launched the sound card has a so-called "hardware support DS3D" capability. DS3D becomes an API interface on this type of sound card. Its actual hearing effect is to look at the strength of the HRTF algorithm adopted by the sound card. EAX: Environmental Sound Efficiency Extensions, ENVIRONMENTAL AUDIO EXTENSIONS, EX is a set of open APIs with innovation and Microsoft, as a set of open APIs extended by DirectSound3D; it is an innovation that is embedded in SB-LIVE through exclusive EMU10K1 digital signal processors to reflect Out; since EAX must rely on DirectSound3D, it is basically used in games. Under normal circumstances, the game programmer uses DirectSound 3D to communicate with the software, EAX will provide new instructions to designers, allowing special effects such as different environmental echoes in real time (such as three-sided wall room) The echo is different from the echo of the fully enclosed room), in other words, EAX is an extension set to enhance the DirectSound 3D function. A3D: is a breakthrough new interaction 3D positioning sound technology developed by Aureal Semiconductor, using this technology application (usually a game) can determine the performance of the sound according to the user's input, generate 3 dimensions around the listener Accurate positioning sound effects in space, bringing a real auditory experience, and can be implemented with two ordinary speakers or a pair of headphones, and through the four channels, it can reflect its positioning effect. H3D: In fact, it has a similar effect with A3D, but because the technology of A3D is registered to Aureal Semiconductor, the manufacturer can only name H3D, Zoltrix speed, AP 6400 night, use C-Media CMI8738 / C3DX Chips, don't underestimate this chip, because it itself can support the H3D technology mentioned above, support four channels, it itself has a modem function. Sensaura / Q3D: CRL and QSound are companies mainly selling and developing HRTF algorithms, they do not introduce instructions. The HRTF algorithm developed by CRL is called Sensaura, which supports most mainstream 3D audio APIs including A3D 1.0 and Eax, DS3D. And this technique has been widely used on the sound card chip of ESS, Yamaha, and CMI, which has become a relatively large technique, which is really good from the actual audition effect. Qsound developed Q3D can provide an environmental simulation capabilities that are similar to EAX, but the effect is still relatively single, which is a little inferior to the performance indicators of Sensaura. Qsound also provides three other sound effect technologies, named QXpander, QMSS, and 2D-TO-3D Remap. Where qxpander is a stereo expansion technology; QMSS is a multi-speaker surrounding technology for 4 speaker mode, which can extend stereo to 4 channel output, but does not add a reverberation effect.
2D-TO-3D Remap is set for DirectSound3D, which can map stereo data to a variable width 3D space, which supports sound cards using Q3D technology. IAS (Interactive Around-Sound): It is characterized by various APIs and technologies discussed above, and they are compatible with each other, and some are water. For game developers, in order to make all users are satisfied, many times must be written for different systems and APIs, which is a very troublesome thing. If there is a new audio technology, the developer will come again. IAS is for this trouble. IAS is the patented audio technology developed by EXTREME AUDIO RE-Ality, Inc (EAR) in the assistance of developers and hardware vendors. This technology can test system hardware and manage all sound platform needs, allowing developers to write only once. It can run everywhere. IAS manages all sound resources for sound designers, providing DS3D support and other surround sound. In this way, developers can make more energy to create real 3D sound, without worrying about compatibility. HRTF: It is a sound positioning algorithm, its practical role is to deceive our ears. Briefly, this is a head-response transport function (Head-response Transfer function). To be specific, it can be divided into several major steps to describe its function. Step 1: Make a head model and install a microphone to the eardrum position; Step 2: From the fixed location, some sounds; third step: analysis from the microphone to get the specificity of the model Data; Step 4: Design an audio filter to imitate that effect; fifth step: When you need to imitate the sound emitted by a location, you can use the above filter to simulate it. The response of the filter is considered to be an HRTF, you need to set an HRTF for each place where there may be a sound source. In fact, we don't need unlimited multiple HRTF. The reason here is also very simple, our brain is not so accurate. It is sufficient to distribute 1000 such functions on the hemispherical surface from our head as the origin, and the other half should be symmetrical. As for the distance sensation, it should be achieved by data changes such as responses, loudness. Sound card external interface: -JoyStick / Midi: standard 15-pin D-type interface, supports joystick and MIDI device-Line Out 1: front speaker or stereo headset (32 ohms), except for two simplified version (Value and Digital Edition) In addition, SB Live! Series are galvanized analog output interfaces. -Line Out 2: Rear speaker, does not support headphones - Microphone in: External analog microphones, no electromagnetic interference -Line in: analog line input built-in interface - TAD: TAD (TELEphone Answering Device, telephone answering device), If you have an automatic answer to MODEM, you can connect it as a more complete multimedia system.
