Sound card working principle and structure

Sound card has gradually become the standard computer configuration, touching music, With it, you will bring immersive experience. I do not think anyone is willing to switch off the speakers around the power play no background music and a variety of audio games. He brought us ears “enjoy” the “heroic”, what is, I want to see the article, you will be able to achieve “a pretty good idea of” the.
Since 1998, the sound card interface has been shifted from the ISA a PCI. Now, in addition to some older machines ISA sound card configuration is outside the market as early as the median value obtained from a rare sight. PCI sound card for its rapid transmission speed, lower CPU utilization and better 3D sound, MIDI excellent performance, winning the market.
# 1 First, the basic structure of the sound card
^ 24030501a ^ under the sound card for the appearance of a map, now the main part of its standard by map numerical order below.
1. Audio processing chips: The main WAVE complete waveform sampling and synthesis, MIDI music synthesis, while mixer, effects in its internal realization is the most basic components of the sound card. Understanding of the sound card, sound card, how the working principle
2. Game / MIDI port: for connecting joystick, lever, steering wheel game controller, such as the outside world, but also can be used to connect MIDI keyboard and electric piano.
3. Linear output jack (LINE OUT): used to deal with a good voice sound card input to active speakers, headphones and power amplifier.
4. Microphone input jack (MICIN): used to connect a microphone, mainly used in speech recognition, entertainment and sound recording and so on.
5. Linear input jacks (LINE IN): used to Walkman or external devices such as TV voice signal input into the computer.
6. Telephone Auto-Answer Device Interface (TAD, Telephone Answering Device): with MODEM card and software will enable computers with automatic telephone answering function.
7. CD audio analog input interface (CD-IN): CD-ROM will come from the analog audio signal access.
8. Auxiliary audio input (AUX-IN): used to MPEG encoder / decoder cards, TV cards, DVD and other equipment解压卡voice signal input sound card, a variety of devices makes the voice signal through the sound card to the speaker.
9. Digital CD audio input interface (CD-SPDIF): role is to receive from the CD-ROM of digital audio signals, to ensure that minimize sound distortion.
10. Daughter card to expand the number of pins (SPDIF-EXT): for the daughter card supporting connectivity, digital signal inputs and outputs. Sound card and dedicated to making digital recording equipment connected (such as: DAT, MD), and the output AC-3 signals.
With the improvement of the overall performance of the computer, it is constantly in pursuit of a more perfect music and sound effects, so the sound card is getting higher and higher demands, today’s sound card has long been a variety of special terminology of the “siege” then we take a look at what they are What does it mean it!
# 1 Second, the basic terminology sound card
Sampling the median: the value of sample value or sampling. It is used to measure changes in voice fluctuations in a parameter, that is, resolution of the sound card. The greater its value, the higher the resolution, the ability to sound stronger. Due to the voice of the human ear accuracy constraints, multi-media computers used 16-bit sound card.
Sampling frequency: the sampling frequency, referring to the voice samples per second to obtain the number. The higher the sampling frequency, the sound quality is better, to restore the voice of the more true, but at the same time it accounts for more resources. Human ear as a result of the resolution is limited, high frequency and can not be identified. In the 16-bit sound card in 22KHz, 44KHz, such as several stages, of which, 22KHz equivalent to an ordinary FM radio sound quality, 44KHz have been equivalent to CD sound quality, and present no more than commonly used sampling frequency 48KHz.
MIDI: is the Musical Instrument Digital Interface abbreviation, which means Musical Instrument Digital Interface. It is an electronic musical instruments, as well as electronic instruments and computer unified exchange agreement between. Many popular games, entertainment software, there are a number of MID, RMI for the extension of the MIDI format music files. MIDI file is a descriptive “music language”, it will have to play the music of information used to describe bytes. For instance, in a moment, what instruments, what note to start, what tone the end of what should be the accompaniment and so on, that is MIDI file itself does not contain waveform data, it is very compact MIDI files. MIDI to the formation of Computer Music must pass synthesis. Early ISA sound card is commonly used in FM synthesis, the “frequency modulation.” Its use of sound oscillation principle of synthesized MIDI processing, due to the limitations of the technology itself, the effect is difficult satisfactory. But now most of the sound card is used in wavetable synthesis, and it will first issue a variety of real musical instruments can all sound (including the various range, tone) for sampling, storage, as a wave table file. In the broadcast, according to documents recorded MIDI music information to the wave form to give directions, from the “form” in one by one to find the corresponding voice message, after synthesis, after processing by the playback. Because it is real musical instruments used in sampling, so the effect of natural better than FM. General wave form of musical instruments sound information to 44.1KHz, 16Bit the accuracy of recording, in order to achieve the most realistic playback. In theory, the wave table synthesis capacity greater the better. According to documents placed sampling locations and by the dedicated microprocessor or CPU to deal with different wavetable synthesis also often divided into soft and hard wave form wave form.
MP3 WAV: is the sound files using a special algorithm 1 ratio of more than 10 compressed into small files stored. And WAV record is the sound itself, so it accounts for a lot of hard disk space. For example: 16 of 44.1KHz stereo sound, a minute to occupy the capacity of about 10MB, and far less compared to MIDI.

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