Weak current College】 【motherboard detailed soft sound card.

<br> <br> May many users will have a feeling that some of the IT media, hardware vendor or hardware experts, introducing a piece such as INTEL810/815/815E, IA693A/694X comes with the motherboard, sound card or other hardware .product, often from their introduction in its onboard sound card is a so-called "soft sound card", and usually breaks <br> <br>-AC '97 Standard, called AC' 97 sound card software. Many users of conventional understanding ., AC '97 has almost become synonymous with soft sound card to and high-performance, is also unique to low-grade consolidation motherboard a noun. So, what is this "AC' 97" is what design thinking is?? <br> .<br> AC would raise the standard of 97 <br> <br> In June 1996, five PC field quite well-known and authoritative software and hardware companies jointly presented a completely new concept of chip-level PC audio source structure, that is ., we now see AC would 97 Standard (AUDIOCODEC97). This 5 computer company includes areas in the motherboard chipset and pivotal position first in market share of INTEL company, sound card industry <br> <br> Leading innovative technology, big brother Singapore company .(the CREATIVELABS), in the area of Japan MIDI YAMAHA Corporation, chipset manufacturing firms United States National Semiconductor and specialized manufacturing information processor system for United States ANALONGDEVICES company. At the same time, AC 97 Standard also would have been a number of other well .-known international brand manufacturers support <br> <br> And cooperation, including the more famous AZTECHLABS, CRYSTALSEMICONDUCTOR, OAKTECHNOLOGY ESSTECHNOLOGY, company, etc. From support AC 97 standard would corporations lineup, AC 97 standard would at that time, its main purpose .is to the future of home PC provides a better, higher quality of the sound source. AC 97 standard would <br> <br> Potential as a new audio source schema, mainly for PC multimedia market demand for increasingly pressing audio source signal processing methods .and sources to enhance the way hardware acceleration of the two functions, and accordingly propose a workable solution. In short, the solution is to put them all integrated in chipset, so as to form a brand new PC audio source schema. Can <br> .<br> To imagine that in the near future PC multimedia sound market will thus trigger a deeper revolution, as was the AGP display card industry standards. <br> <br> 97 years later, the market's most have begun PCI sound card with AC .'97 Standard specification, the simulation of the circuit from the sound card chip can be independent, in a piece called udioCodec small chip, as shown in the upper-left corner of the block, WM9701 is Wolfson production AC' 97 chip, the chip .is in the middle of the large FORTEMEDIA FM801, the company can call <br> <br> DigitalControl is digital, short for DC '97 chips. DC' 97 completed most of the audio features, such as WAV playback, MIDI synthesis, sound .processing, and so on, then turn the PCM digital signal through and AC '97 connected 5 leads sent to AC' 97 chip, chip by AC '97 complete digital and analog signals of the converted output to speakers. Don't look at AC .'97 chips only 7X7mm see <br> <br> Party, 48 feet of TQFP package, it can be done than ordinary DAC more functionality, also contains the analog signal to digital signal for ADC, multi-channel analog signal mixing input and output ., like audio digital encoding / codec, and the lead role of the amplifier. Figure 1 the upper-right corner of the VIDEO PHONE interface, you can join the second only the CDROM and TV card audio output. Different <br> <br> .AC '97 compatible chip, between pin substitutable in principle, when you purchase a sound card to watch out for AC' 97 chip model, because the AC '97 chip manufacturers, performance is also very different. Early PCI sound card price is high, .the materials are also used, such as YAMAHA724 audio AC '97 chip using the SigmaTel STAC97 series, and later in order to reduce costs, mining <br> <br> With cheap AC' 97, performance chip falling instead of rising, it is .important to note that at the time of purchase. May wish to look at the high-end audio AC '97 chips, write down the model number and manufacturer for comparison when choosing the sound card. SigmaTel's STAC97 series common for sound cards, such as .innovative PCI128Digital adopts STAC9708 chip supporting 4-channel output. SigmaTel latest S <br> <br> TAC9744 chip-to-noise ratio up to 96 DB. Like the AD, Crystal, Winbond etc. different AC '97 chip performance than it low ., but most can reach 80 DB Snr, common in the middle and a sound card and motherboard integrated sound. Have a sound card that SNR is good, in fact and not what the relationship between the main chip, which is the battle with AC ' .97 chip performance and outstanding. <br> <br> Normal AC '97 chips thousands block at around us $ 4, brand-name product price. This allows some sound card manufacturers change circuit design, the market price falls below 100 common sound card .is not used AC '97 chips, like CMI8738, ALS4000, VIBRA128, etc., are single-chip architecture, digital and analog isolation, although the Department not to reduce costs, yet-to-noise ratio is <br> <br> .Less than 80 DB. Now you can go back and look at the motherboard for the AC '97 sound card is what theFrom VIA and INTEL have joined in the southbridge chip features of your sound card, sound card via a simulation software, complete the General .sound card chip features, audio output is handed a piece of AC '97 chip finish. So this kind of Board do not see there are bigger sound chip, only a small <br> <br> Small AC' 97 chips. And directly integrated .hard sound card, as a software simulation, CPU usage than regular sound card, if the CPU speed does not meet requirements or because the driver software problems, it is easy to produce explosive sound impact sound quality. To troubleshoot similar problems and improve performance, .the Board adopted the integrated hard sound way, more formal AC '97 also conform to the standards, there is a more <br> <br> Larger mainstream sound chip, there is also a small AC' 97 chips. And low-cost integrated .sound often use does not comply with the standard AC '97 sound card, eg quadraphonic sound effects such as CMI8738 chip, the chip costs and higher end AC' 97 chips also high not to go there, but users are more willing to accept hard sound .card, and not to care about whether the other with AC '97 chips. So you can say, by five <br> <br> Industry manufacturers jointly implemented a new AC 97 standard specifications would fundamentally improves on traditional sources, the first of a .two-chip structures. AC 97 standard would combine digital and analog processing dual benefits, on the one hand, reduces the conversion from analog line to a digital line may be a noise, creating a more pure sound quality; on the other hand, will .<br> <br> Sound processing integrated into the chipset, you can further help manufacturers reduce costs. In addition, from another angle, along with the USB standard and the increasingly popular IEEE1394, and current PC sound signal is still only available via PCI .or ISA bus for transmission, or indeed to be the must be improved. Time and tide, AC 97 standard specifications would also is the face of such <br> <br> A situation has arisen. For end-user consumers, both can be .more than the previous high-quality high-quality sound, but also to further reduce the cost of their acquisition, and two birds with one stone, why? <br> <br> AC 97 standard specifications would <br> <br> Dual .chip PC sound solutions; <br> <br> Two standard package: 48 pin and a 64-pin; <br> <br> Digital / analog signal separation, to improve the signal to noise ratio (> 90db); <br .> <br> 16-bit stereo-duplex codec, fixed 48K sampling frequency; <br> <br> 4 analog stereo LINE input from, CD, VIDEO, AUX; <br> <br> Two analog mono input from the microphone and .PC speaker; <br> <br> From two external audio source switching Mono microphone input; <br> <br> High-quality CD input; <br> <br> Stereo line-out; <br> <br> Phone mono .output; <br> <br> Support power management; <br> <br> Optional tone control; <br> <br> Optional treble control; optional 3D stereo enhancement; <br> <br> Optional stereo headphone output; <br .> <br> Optional 18 or 20-bit DAC and ADC resolution; <br> <br> Optional MODEM linear codec (ADC and DAC); <br> <br> You can select the microphone and the third ADC input channel. < .br> <br> It is not difficult to see from the above, AC '97 Standard for circuit requirements more stringent. According to AC' 97 Standard, due to the higher integrated IC circuit, DAC, ADC and other related digital circuits integrated into .a chip form, not only to reduce the overall system design costs, while you can get better, more effective sound effects. It is entirely possible to signal to noise ratio from their <br> <br> You can see few requirements 90db. In .addition, as a result of the dual-chip design forms, manufacturers are in the terms of the design can be more flexible, easier throughout the system integration. At the same time, in a sense, AC '97 Standard is also an important topic .for another, that is 100% digital audio PC provides a complete solution. Then, the new concept came again, what <br> <br> Is 100% digital audio PC? as the name suggests, that in a PC, all the sound .source or output is handled by digital, even in the computer, all sounds are also a number of ways to transfer. In this way, users who want to get better sound effect that to avoid a digital line with analog line conversion process may produce < .br> <br> A lot of noise. Previously, the costs, maintain backward compatibility, and unable to effectively use PC resources system, and many other factors (such as CPU, RAM, bus), 100% digital audio PC has not a .practical solution. AC '97 Standard is properly taken into account, "and bus-independent" concept of sound output. In this scenario, the sound <br> <br> Signal is still available through traditional bus transport, such as ISA or PCI .. But now it can also be redirected to the USB or IEEE1394 bus, so the analog output (DAC do in PC internal, sound output to the standard stereo speakers) or digital output (DAC do in PC external, sound output to the USB or .IEEEE1394 connector, the so-called USB speakers, etc.) <br> <br> Have the freedom, either to the left. <br> <br> AC '97 hardware acceleration mechanisms <br> <br> Traditional audio hardware acceleration .: IN-LINE following author to play a DVD, for example, let's briefly explain the traditional sound processing speed. We all know, a computer when playing DVD-ROM CPU processor mustIs the encoding of Dolby film sound from MPEG-2 AC-3 .separated and placed in the DRAM buffer, and then through AC-3 hard <br> <br> Pieces extracted from the DRAM buffer will sound data, decode, and 5.1 channel mixed into a two-channel output, eventually reaching IN-LINE audio .hardware acceleration. Understand this point, the following then let's contrast see AC '97 compliant audio hardware acceleration modes: AC' 97 multi-trip conforms to the standard specifications of the chipset and traditional sound <br> <br> Output mode, sound data .can be changed to the transmission to the USB or IEEE1394. Its specific implementation has the following main steps: the first step by AC-3 hardware acceleration appliance from DRAM to extract out the CPU processor prior had been isolated from the data; the second step .performed by AC-3, decompressing and mix the synthesis of data into another piece in the DRAM cache <br> <br>. .This will produce an interrupt signal to tell the operating system, the synthetic sound data ready; the third step of the operating system with the CPU processor will have to deal with sound data transfer to the new buffer, and then the data is fed into the .USB output pipeline, wait; the last step is to obtain the associated USB controller voice data is sent to the corresponding digital loudspeaker <br> <br> Device. <br> <br> How to implement the system AC '97 Standard <br .> <br> In order to allow manufacturers to true will meet AC '97 compliant chipset to smoothly migrate to the motherboard, the INTEL Corporation recommends that the designer uses the following three ways: <br> First, the controller and sound decoding chip all .integrated on the motherboard, so that both be through AC-LINK communication. The advantage is that the chipset and motherboard integration degree <br> <br> You can achieve the best; <br> <br> Second, do the controller on the .motherboard, but will sound decoding chip do in interface card, let them still communicate through AC-LINK. In this way, users can compare the flexibility to select decoder chip. In addition, the interface can also be selectively add modem voice part transport feature .. <br> <br> Third, the controller and decoding chip were all done on a card, 32-or 64-bit PCI bus to communicate with other peripherals. Of course, the use of USB and IEEE1394 or boards communications are also possible ., as long as the controller can support IEEE1394 or USB interface. Of course, in addition to matching a SIDEBANDHEADER signal cable, complete controller and motherboard <br> <br> Connection. It should be said, in this way the difficulty of design, .design firms are as long as the motherboard in your motherboard aside SIDEBANDHEADER signal cable outlet and the associated circuit is all OK. <br> <br> AUDIO'98 <br> <br> At INTEL, etc. the company AC '97 standard .specifications, the specifications for the incoming audio source, INTEL has introduced a new concept, which is the standard AUDIO '98. In AUDIO' 98 standard, it is not difficult to see the following features and technology enhancements: <br> <br> .First, further enhancing the efficiency of CPU processor utilization. When the CPU efficiency increases, users can utilize computer software offers more audio processing functions; second, the integration of different functional requirements. Overall improvement in the sound controller and other devices on the motherboard, .the integration will voice interfaces to low-cost ways into the SUPERIO or other class <br> <br> Like chipset; <br> <br> Third, join the exterior appliance extension bus. Use this type of exterior appliance extension bus can further .increase system design flexibility, enabling users to more easily upgrade. Ultimately you want to replace the current USB bus ISA bus. It can be inferred that user for PC sound quality requirements become more stringent. <br> <br> <br> <br .> <br>.