Common Hardware glossary! Absolutely authoritative! (Go !) Vi. Sound Card terminology

Vi. Sound Card terminology
　　
DSP: digital signal processing (Digital Signal Processing ). DSP technology is widely used in analog electronics, such as Tone Control, distortion effect generator, and wah-wah pedal. At the same time, the DSP can also be used in a variety of effects, such as analog balancing and reverb. You can perform DSP operations through a computer CPU or a specialized DSP chip. The difference is that the processing of a specialized DSP chip is more optimized and faster than that of a computer CPU.
　　
Sampling: the process of converting analog audio into digital audio is called sampling. The main device used is the analog/digital converter (analog to digital converter, that is, ADC, it corresponds to the number/mode converter, that is, DAC ). The sampling process is actually to convert the electrical signals of analog audio signals into binary codes 0 and 1. These 0 and 1 constitute a digital audio file. The higher the sampling frequency, the higher the sound quality. Because the sampling frequency must be twice the highest recording frequency, human hearing ranges from 20Hz ~ 20 kHz, so the sampling frequency must be at least 20 k × 2 = 40 kHz to ensure that low frequency distortion is not produced. This is also the use of 44.1 kHz for CD sound quality (slightly higher than 40 kHz is to leave room).
　　
Signal-to-Noise Ratio: the ratio of the maximum fidelity output to the inevitable electronic noise calculated by DB. The larger the value, the better. Below 75 dB, noise may be detected in silence. The signal-to-noise ratio of the awe64 gold sound card is 80 dB, which is reasonable. SB live! It is also the top-level signal-to-noise ratio that claims to exceed dB. In general, the signal-to-noise ratio of sound cards is often unsatisfactory due to high-frequency interference in computers. But Sb live! It provides a digital output port spdif, which can bypass the analog part of the output, greatly reducing noise and distortion, and greatly improving the dynamic range and definition.
　　
Sound Card: as the name suggests, it is a sound card. It is like the vocal cords in a person's throat. With it, you can make a sound, communicate, and sing. Sound cards also play a role in computers. They can implement human-computer communication, such as learning foreign languages and voice input. Sound cards are called sound cards or sound cards in Hong Kong and Taiwan. They are indispensable in multimedia computers, and computers also have sound functions. Sound cards are essential for computer musicians because they are much better than traditional production methods. Sound Card brings you into a "colorful" sound world, allowing you to fully feel the wonders of nature.
　　
Synthesis Technology: There are two types of Sound Card synthesis technology: first, FM Synthesis Technology (frenquency Modulation Frequency Modulation); second, wave table synthesis technology. The FM synthesis technology uses a computational method to express the real voice of an instrument. It can simulate multiple sounds without a large storage capacity. The structure is simple and the cost is low, however, it has poor imitation capabilities. The English name of A wave table is "wave table. In fact, it records all the sounds that a variety of real instruments can make (including various audio domains and tones) and stores them as a wave table file. During playback, a command is sent to the wave table based on the music information recorded in the MIDI file. The corresponding sound information is found from the wave table database one by one, and then played back after synthesis and processing. Because it uses the sampling of a real instrument, the effect is naturally better than that of FM. Generally, the sound information of the instrument in the wave table is recorded with 44.1 kHz and 16 bit accuracy to achieve the most authentic playback effect.
　　
"Soft" wave table technology: it is a form of software (the wave table in the sound card is stored in the hard disk, the CPU is called out when used) instead of the wave table.
　　
DLS: the downloadable audio source module is a new technology used by the PCI sound card. It stores the wave table on the hard disk and needs to be transferred to the memory. however, it is different from wave table. DLS uses a dedicated chip's PCI sound card to synthesize music, while soft wave table technology uses CPU to synthesize music.
　　
Sound Font: it is a sound library technology used by Singapore's innovative companies in mid-range sound cards. It is a combination of characters. A sound fond represents a set of music symbols. When you enter a music character on the Midi keyboard, the Midi parameters are automatically recorded and finally searched in the sound fond. when you need it, you can download it to the sound card. One of the biggest advantages of this solution is that it will not affect the sound quality because of insufficient storage capacity of the sound card, and will be able to achieve the ideal environment for full tone and tone. Currently, this method is only applicable to high-end sound cards. There are two reasons, of course, apart from the innovative audio library, there is also Microsoft's DLS standard. In comparison, the sound font technology is very practical, but only innovative sound cards can be used. Microsoft's DLS is mostly used on PCI sound cards.
　　
Wave table sub-card upgrade: you can upgrade the FM sound card to the wave table sound card. However, the original sound card must have an upgrade interface. Because the brands of various sound cards and the memory supported by sound cards are different, the price difference is great. For those who use the FM sound card, it is a good choice to upgrade the sub-card. However, it also has a problem of performance/price ratio, and whether it is worth further consideration.
　　
Number of sampling digits: the sampling value or sampling value. It is a parameter used to measure the fluctuation of sound, that is, the resolution of the sound card. The larger the value, the higher the resolution, and the stronger the sound. The bit of a sound card is the binary number of the digital sound signal used by the sound card to collect and play audio files. The location of the Sound Card objectively reflects the accuracy of the digital sound signal on the input sound signal description. You can use a 16-bit sound card in a multimedia computer, because the voice resolution is less than 16.
　　
Sampling frequency: the sampling frequency, which refers to the number of times the sound sample is obtained per second. the higher the sampling frequency, the better the sound quality, but it occupies a large amount of memory. since the resolution of human ears is very limited, the Ethernet high frequency cannot tell the quality. the sampling frequency is generally divided into three levels: 22.05 KHz, 44.1 KHz, and 48 KHz. 22.05 can only achieve the sound quality of fmbroadcast. 44.1KHz is the theoretical CD sound quality limit, while 48 KHz is more accurate. Human ears can no longer identify the sampling frequency higher than 48 khz, so there is little value for use on the computer.
　　
DAC: A computer cannot directly process a sound signal. to convert it into a digital signal that the computer can recognize, it must use the DAC (digital/analog conversion) in the sound card ), it converts a sound signal into a digital signal, which consists of two steps, sampling and conversion.
　　
Audio Source: literally, it means the source of the sound, that is, the source of the sound. It mainly expresses the sound completely and accurately. It can be divided into two forms: external, which is not restricted by the sound card. The sound quality can be well preserved, but the cost is very high. Built-in, also known as audio source card.
　　
Audio source card: it has its own source of music, but must be attached to a hard disk used on the sound card. You can use a sound card with a WAVE blster plug on your computer. The requirement for using the audio source card is very low. It does not occupy interruption, the address is not re-selected, and the driver is not required. You just need to set the MIDI port to sb midi out.
　　
Polyphone: This replay is not the "consonants" learned in English. It refers to the number of sound cards that can sound at the same time. if you play a MIDI music, the number of replay must be smaller than or equal to the number of replay sound cards you use, you can hear the best results. therefore, the more replay sounds you have, the more wonderful music you will be able to hear. but you will spend more money.
　　
MP3: It compresses audio files by a ratio of 1 to 10 into a small file and stores it on the disc. we usually listen to a VCD with only 10 or 20 heads, but it is not a problem to put hundreds of heads on a disc processed by MP3 files. This is good for computer music enthusiasts.
　　
MIDI (musical indtrumend digital interfoce digital interface): it is not a music signal. To play the recorded sound, you must set it on the Midi interface. It is the standard for the use of electronic synthesizer and digital music, and also a bridge between computer and electronic instrument. It is a good choice for computer music lovers.
　　
Wav: in windows, the audio file is stored on the hard disk with the extension WAV. Wav records the sound itself, so it occupies a lot of hard disk space. For example, a 16-bit stereo sound of 44.1khz occupies about 10 MB in one minute, which is far from Midi. In this case, the sound card compression function is equally important.
　　
WOC: A storage form of audio files. Files with an extension of VOC can be played in the DOS system. It is only in different formats than WAV, and there is no fundamental difference in the core part. In this form, a digital signal is first converted to a digital/analog signal, and then sent from the amplifier to the speaker for sound.
　　
Avi: (Audio-Video interactive) Audio and Video interaction. It is an audio and video signal compression standard launched by Microsoft.
　　
Single Channel: single channel is a relatively primitive sound replication form, and early sound cards were widely used. When two speakers play back the single channel information, we can clearly feel that the sound is transmitted from the middle of the two speakers to our ears. This kind of recording method with a lack of Location Awareness is very backward, but it is already a very advanced technology when the sound card is just getting started.
　　
3D stereo system: it is what we usually call 3D. the sound effects of sound cards are enhanced from three aspects: first, the sound we hear is enhanced, second, the sound displacement, and third, the reverb effect. whether in your own home or in a cinema, whether in a VCD or a video album, there will be two channels on the screen each time you choose to be "Left" "Right ", we have to choose all of them. The sound of two sound channels is mixed together, which sounds shocking. but it does not have a 3D surround sound system.
　　
3D surround sound system: over a dozen 3D Systems have been put into use since the emergence of 3D in 1980s. up to now, two technologies have been used on multimedia computers, namely space balancer and SRS (sound Retrieval System) Sound correction systems. let's talk about space first: it uses the sound effect and the acoustic imitation principle to achieve 3D effect based on the different sensing effects of the human ear on the sound without adding sound channels, people feel that the voice comes from all Parties; SrS: it completely utilizes the acoustic imitation principle and the voice of the human ears space is different from the sensing, processing the two-channel stereo signal, although the voice comes from the front, but people mistakenly think it is from all directions. this kind of system only uses two normal audios, and can have the shocking effect of the concert hall. It does not include the book, so it is very attractive.
　　
Quasi-Stereo Sound: the basic concept of a quasi-stereo sound card is to use a single channel when recording a sound, while a sound is sometimes a stereo or a single channel. Sound cards using this technology have also been popular on the market for some time, but they have disappeared.
　　
Four-way surround: four-way surround specifies four pronunciation points: front left, front right, back left, back right, audience is surrounded in the middle. At the same time, you can add a bass speaker to enhance the playback of low-frequency signals (that is, the 4.1-channel speaker system ). In terms of the overall effect, the four-way sound system can bring sound from multiple different directions to the audience, and provide users with a new experience. Nowadays, the four sound channels technology has been widely integrated into the design of various medium and high-grade sound cards, and become the mainstream trend of future development.
　　
5.1 channels: some well-known sound recording compression formats, such as Dolby AC-3 (Dolby Digital), DTS and so on are based on the 5.1 sound system for the technical blueprint. In fact, the 5.1 sound system comes from the 4.1 surround. The difference is that it adds a central unit. This center unit is responsible for transmitting sound signals less than 80Hz. It is helpful for enhancing the voice when you enjoy the video and concentrated the conversation in the middle of the sound field to increase the overall effect.
　　
Dolby Logic Technology: Dolby Pro-Logic is developed by the Dolby laboratory in the United States. It is used to restore sound, which has a great feature, it is to encode the original sound of the four channels (both sides and sides) to form a dual-channel signal. When the sound is loud, it is first sent to the amplifier through the decoder, with the help of the intermediate stage surround sound speaker, in this way, there is an on-site surround sound effect, so that the previous plane sound field is changed.
　　
DDP circuit: DDP (Double Detect and Protect: Dual detection and protection), it can enable Space to no longer repeat the input signal, while detecting the sound frequency and direction, and automatic adjustment to get the best results.
　　
DSP (Digtal Signal Processor: Digital Signal Processor): It is a dedicated digital Signal Processor. It was "elegant" on a high-end 16-bit sound card ". It is a great honor to enable surround sound for high-end sound cards. However, with the continuous development of new technologies, the contradiction between DSPs becomes more and more prominent. Sound Card Providers have to "reluctantly cut down" costs for their own interests.
　　
HZ: The unit used to describe the sound vibration frequency, also known as CPS (Cycles Per Second). One vibration cycle is called 1 HZ. The human ears can hear the audio at around 20 HZ to 20 KHZ.
　　
Encoding and decoding: in digital audio technology, the digital size is used to replace the analog voltage of sound intensity and height, and the compression process of audio data is called encoding. During music replay, then, the compressed data is restored, which is called decoding.
　　
Signal-to-Noise Ratio (SNR: Signal to Noise Ratio): It is an important indicator to judge the Noise ability of the sound card. The ratio of the signal to the noise signal is SNR, in decibels. The greater the SNR value, the better the filtering effect of the sound card, generally greater than 80 decibels.
　　
Frequency Response (FR: Frequency Response): It is a standard for evaluating the Frequency Response capability of the audio card ADC and the AC converter. The voice reception range of human ears is 20 HZ-20 KHZ. Therefore, the audio signal of the sound card must always be in a straight-line response within this range. If the appearance (represented by power gain in the sound card data) or the decline (with power attenuation) is distorted.
　　
Total Harmonic Distortion (THD + N: Total Harmonic Distortion + Noise): THS + N is an evaluation of the fidelity of the sound card. It compares the matching degree between the input signal of the Sound Card and the waveform of the output signal. The lower the value, the smaller the distortion. In this formula, "+ N" indicates that noise is also considered while considering the fidelity.
　　
Direct Sound 3D: The old audio API originated from Microsoft DirectX. Its role is to help developers Define the positioning and sound of sound in 3D space, and then deliver it to DS3D compatible sound cards for them to be implemented using various algorithms. The effect of sound location depends on the algorithm used by the sound card. For sound cards that do not support DS3D, it is used by a CPU-consuming HRTF algorithm, so that these early products have the ability to process 3D sound effects. However, the actual results and execution efficiency are not satisfactory. Therefore, since then, the sound card has a so-called "DS3D hardware support" capability. DS3D has become an API interface on such sound cards. The actual auditory effect depends on the strength of the HRTF algorithm used by the sound card.
　　
EAX: Environment sound extension, Environmental Audio Extensions, which is jointly provided by innovation and Microsoft as an open API for DirectSound3D extension; it is embodied through the exclusive EMU10K1 digital signal processor embedded into the SB-LIVE; Because EAX must currently rely on DirectSound3D, it is basically used in the game. Under normal circumstances, game programmers use DirectSound 3D to communicate hardware and software. EAX will provide new instructions to designers, allows real-time generation of special effects such as Echo of different environments (for example, echo of a wall room on three sides is different from echo of a fully enclosed room). In other words, EAX is an extended set, enhanced the DirectSound 3D function.
　　
A3D: a groundbreaking new interactive 3D positioning sound technology developed by Aureal semicondu. it is used by applications (usually games) you can change the sound effects based on user input, and generate precise positioning sound effects around the listener's three-dimensional space, bringing a real auditory experience, in addition, it can be implemented with only two normal speakers or a pair of headphones, and the positioning effect can be well reflected through four sound channels.
　　
H3D: in fact, it has almost the same effect as A3D, but because A3D technology is registered for Aureal semicondu, the manufacturer can only name it with H3D, the AP 6400 Nightingale in Zoltrix fast-release, the C-Media CMI8738/C3DX chip is used. Do not underestimate this chip, because it supports the H3D technology mentioned above, supports four sound channels, and also has MODEM functions.
　　
Sensaura/Q3D: CRL and QSound are companies mainly selling and developing HRTF algorithms. They do not provide instruction sets themselves. The HRTF algorithm developed by CRL is called Sensaura and supports most mainstream 3D audio APIs, including A3D 1.0, EAX, and DS3D. In addition, this technology has been widely used in sound card chips of ESS, YAMAHA and CMI, which has become a technology with a great impact. It is indeed good from the actual audition results. Q3D developed by QSound can provide an environment simulation function similar to EAX, but the effect is still relatively simple, which is slightly inferior to Sensaura's large and comprehensive performance indicators. QSound also provides three other sound effects technologies: QXpander, QMSS, and 2D-to-3D remap. QXpander is a stereo extension technology, and QMSS is a multi-speaker surround technology used in the 4-speaker mode. It can extend the stereo to 4-channel output without the addition of the reverb effect. 2D-to-3D remap is designed for DirectSound3D games. It maps stereo data to a variable-width 3D space. This technology supports the use of Q3D sound card technology.
　　
IAS (Interactive round-Sound): The various APIs and technologies mentioned above have their own characteristics. Some of them are compatible with each other, while others are difficult to understand. For game developers, It is very troublesome to write multiple sets of code for different systems and APIs to satisfy all users. If a new audio technology emerges, developers will try again. IAS is aiming at this problem. IAS is a patented Audio technology developed by Extreme Audio Re-ality, Inc (EAR) with the assistance of developers and hardware vendors. This technology can test system hardware, manage all the requirements of the sound platform, allowing developers to write only once, that is, they can run anywhere. IAS provides DS3D support and other surround sound execution for sound effects designers to manage all their audio resources. In this way, developers can free up more energy to create real 3D sound effects without worrying about problems such as compatibility.
　　
HRTF: it is a sound effect locating algorithm. Its actual function is to cheat our ears. Simply put, this is a Head-Response Transfer Function ). The specific points can be divided into several main steps to describe their functions. Step 1: Create a head model and install a microphone to the ear mask; Step 2: Make some sound from a fixed position; Step 3: analyze the sound obtained from the microphone and obtain the specific data changed by the model. Step 4: design an audio filter to simulate the effect. Step 5: when you need to imitate the sound from a location, use the above filter to imitate it. The response of the filter is considered as an HRTF. You need to set an HRTF for each location where there may be a sound source. In fact, we do not need an infinite number of HRTF. The reason is also very simple, and our brain cannot be so precise. It is sufficient to have about 1000 such functions distributed on the semi-spherical surface with the origin of our head, and the other half should be symmetric. As for the sense of distance, it should be achieved by data changes such as ECHO and response.
　　
Sound Card external interface:
-Joystick/MIDI: Standard 15-pin D interface, supporting game rods and MIDI Devices
　　
-Line Out 1: front speakers or stereo headphones (32 OHM), in addition to two simplified versions (Value and digital), SB Live! The series are both gold-plated analog output interfaces.
　　
-Line Out 2: Rear speaker, not supported
　　
-Microphone In: external analog Microphone without electromagnetic interference
　　
-Line In: analog Line Input built-in Interface
　　
-TAD: TAD (Telephone Answering Device). If you have a Modem for automatic response, you can connect to it as a more complete multimedia system.
　　
-CD Audio: CD Audio interface, which can be used to play CD music through a speaker connected to the Sound Card
　　
-AUX: interfaces connected to other built-in devices, such as TV/FM tuning cards, MPEG decoding cards, and MIDI dedicated cards.
　　
-I2S: zooming video digital inputs for innovative PC-DVD digital sound mixing/surround Systems
　　
-S/PDIF: S/PDIF (Sony/Philips Digital InterFace): Abbreviation of SONY and PHILIPS Digital interfaces, jointly developed by Sony and Philips) (for civilian use), AES/EBU (professional) Interface format. Generally, a DIGITAL audio source has a digital output terminal, so that you can use a DAC (DIGITAL-to-analog converter) with better external quality to improve sound quality or connect to other audio devices. It can avoid extra signals resulting from analog connections, reduce noise, and reduce signal losses caused by Analog-to-analog conversion and voltage instability. Because it can sample audio at 20 bits, it can maintain and Process audio signals in a high-precision digital module. S/PDIF makes the entire system maintain a high quality, so the sb live using S/PDIF surpasses many home stereo systems in terms of fidelity, connectivity and innovation. The Data Stream Transmission Mode S/PDIF can be subdivided into the following two forms: 1. TOSLINK; 2. Coaxial on the same axis.
　　
-Microphone: connects to the internal Microphone and can input the sound output from other expansion cards.
　　
-Modem: connect to the built-in Modem. You can use the existing microphone/speaker settings to control the DSVD or speaker of the Modem.
　　
-Digital I/O Header: AUD_EXT40-pin interface. Digital Input/Output daughter cards are connected with band cables. More additional device Digital I/O Card interfaces are supported.
　　
-Digital DIN: connect to Cambridge Soundworks 7.1 eight-speaker desktop theatre System
　　
-Spdif in: External RCA Digital Input
　　
-Spdif out: External RCA digital output
　　
-Mini-din midi in: Additional MIDI inputs
　　
-Mini-din midi out: Additional MIDI output