Introduction to the sound card chip on the motherboard-EEWORLD

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Introduction to motherboard sound card chip

The current motherboards are basically integrated with audio processing functions. According to a survey, more than 80% of users who install new computers use the motherboard's built-in sound card. The main reason is that most users do not have very high requirements for PC sound quality, and do not want to waste the existing onboard sound card; in addition, the onboard sound card has been quietly undergoing a revolution, and the sound quality is no different from that of an ordinary PCI sound card, or even better. In the long-term development process, onboard sound cards are no longer just "soft" or "hard" as in the past. There are quite a lot of types, and their differences are also very large. Let's talk about what kinds of onboard sound cards are currently on the market, what are their characteristics, and how to identify them when buying. I hope you will be more careful when buying motherboards and enjoy better sound effects without spending money.

AC97 basic framework

The AC97 architecture consists of three parts :

Signal processing part: DSP, which can also be replaced by CPU , due to the powerful processing power of CPU, this is completely feasible. But it needs software driver to implement the algorithm. Software is much more flexible, which is also the capital that manufacturers can realize many advanced functions of PCI sound cards at a low price.

Digital connection part: integrated in the south bridge chip, the digital controller (DigitalController) and AC-link are responsible for connecting, controlling and "packaging" data (arranging digital information according to the AC97 standard). As shown in the figure above, the middle part is a component in the south bridge. The lower right picture is the south bridge of VIA's latest KT400A.

Audio playback Part: AC-link connects to Codec , Codec is the representative part of the soft sound card that we often hear about and is also the only one that can be seen on the motherboard. Only the playback or input part (digital-to-analog conversion DAC/ADC, audio mixing and other functions) is built. It is the right part of the above picture. As shown in the right picture, VT1616 is the Codec.

Basic performance

The basic performance achieved by the Codec is specified in the standard:

Dynamic>90dB
Supports stereo headphones
16-Bit stereo full-duplex stereo output
16-Bit mono headphone output
Support four analog stereo input modes: LINE-IN, CD, VIDEO, AUX
Support AC97 mixer
External Audio Power Control
Sampling frequency: 48Khz, 32.0Khz, 22.05Khz, etc.

18-bit and 20-bit sampling accuracy, increased signal-to-noise ratio (partly greater than 98db)
Full-duplex variable sampling rate (linearly change from 7040Hz to 48kHz in 1Hz increments)
Enhanced 3D stereo effect
S/PDIF output
Extended 6-Bit Master Volume Control
Supports four analog stereo input modes: LINE-IN, VIDEO, AUX and high-quality CD audio input
Jack probes provide automatic output control
Enhanced power management (to support digital signals)
Mono MIC input (built-in 20dB preamplifier)
Multi-Codec design allows 3 CODEC chips to work simultaneously through the CRN interface

AC97 sound card is highly dependent on the driver. The sound quality and 3D effect are actually mainly determined by the driver and algorithm. However, without certain hardware support, the driver is powerless no matter how powerful it is. Therefore, there are certain differences in the functions of Codecs of different grades. The upgrade of AC97 Codec is mainly reflected in the overall function upgrade, such as S/PDIF output, preamplifier, etc.

AC97Codec may not be satisfactory, but for general users, I think it should be enough. We are not professionals, and it is difficult and unnecessary to distinguish the sound too clearly.

What level does AC97Codec belong to? Just listening to the motherboard manufacturer's theory is not enough, here are some practical tips!

Selection of onboard soft sound card

Location

Codec chip, in fact, many motherboards will declare it themselves, so you can be more careful and see what chip is used. As for the specific chip features, I will explain them later. It is usually in the upper right corner of the motherboard, or near the audio output jack, as shown below:

Codec packaging has a fixed standard. The 48-pin QFP package, which is clearly defined in the INTEL standard, is a square package with pins on all four sides. Let's take a look at it:

General chip model

Dual Channel

The early models mainly include: VIA's VT1612a; Realtek's ALC100/P, ALC101; SigmaTel's STAC9708T; Analog Devices' ad188x series (perhaps you have rarely heard of this name, but it is INTEL's main partner, and most INTEL motherboards have built-in sound cards using its CODEC).

After seeing these types of Codecs, I suggest you buy another sound card as soon as possible, after all, their functions are too poor.

Many Codec manufacturers that launched their products later also paid attention to this, and finally achieved not only the level of being able to produce sound, but also made great improvements in sound quality and functionality.

VIA's VT1611A; Realtek 's ALC201, ALC202/a; Crystal 's CS4201, CS4202, CS4205, CS4294, CS4297A, CS4299; SigmaTel 's STAC9756/57; C-MEDIA 's CMI8738 (it has built-in 4-channel capability on a dual-channel interface); AnalogDevices ' ad198xA/B series, ad183x series.

Codec is designed according to the higher requirements of AC97 standard: dual channels, generally with 18bit/20bit digital-to-analog conversion capability (improved sound restoration capability), extended 6 or 5-bit master volume control, additional headphone amplifier or output line amplifier, and a small number have S/PDIF output.

C-MEDIA's CMI8738. It can be regarded as the best product of this generation, with extremely rich functions, including 4-channel capability, AC-3 output, HRTF3D positioning algorithm interface, etc. In fact, it already includes some audio processing capabilities, such as 3D computing functions are no longer completed entirely by the CPU, but its improvements have not completely reached the standard of hard sound cards. I think it is better to classify it as a soft sound card. It can be regarded as a choice between general AC97 and hard sound cards. In addition, many PCI sound cards also sample this chip.

Codec, the onboard sound card function has been further improved.

Realtek's ALC203; SigmaTel 's STAC9752/53, STAC9766/67.

DirectSound3D, HRTF3D, Sensaura™3D, EAX™1.0&2.0 and A3D functions; partially supports DVD playback; optical fiber output supports 32K/44.1K/48K/96KHz multiple frequency options for the first time.

Six channels

Codec has not stopped either and is now able to achieve this function.

Codec; second: build multi-channel based on dual-channel output, still using dual-channel Codec ; third, multi-codec technology , multiple CODECs are connected to AC-LINK to process the front, rear and center channels respectively.

Method 1:

VIA's VT1616; Realtek 's ALC65X series (ALC655 and ALC658 are enhanced models); C-MEDIA 's cmi9739/a; SigmaTel 's stc9758/59;

Method 2: The Crystal implementation method is to use a CS4202 plus a CS4334 expansion.

Take Crystal as an example, the wholesale price of a single CS4202 CODEC is 1.4$, and a single CS4334 chip is 0.7$, totaling 2.1$, equivalent to about ￥17 yuan. Good quality and low price!

XEAR3D technology, Analog Devices ' SOUNDMAX3.0 technology. Due to the uniqueness of the soft sound card, it is possible to upgrade the driver to upgrade the sound card.

Method 3: connect another Codec through the CNR port .

The AC97 standard actually recommends this method, but due to its high cost, it is now mostly seen on branded machines. Some manufacturers have also launched such sound cards. For users with CNR ports, it provides another option to upgrade the original 2-channel to multi-channel.

If the motherboard has a built-in CODEC of the same or compatible series as the CNR card, a slave CNR card can be used as a channel upgrade solution. That is, if the motherboard has a built-in two-channel CODEC, you can use a slave four-channel CNR sound card with the same or compatible CODEC to upgrade the system's channels from the original two channels to six channels.
If the motherboard does not have any built-in CODEC or does not want to use the sound effects on the motherboard, the user can select the master mode, just like a normal sound card. The master type CNR sound card automatically turns off the CNRCODEC built into the motherboard and only uses all the sound effects on the CNR card.
Onboard hard sound card
APU realizes the function of hard sound card.

ct5880: I don't want to say much. It has a low-end PCI sound card on top and a 6-channel soft sound card on the bottom. It is in an awkward position. If you have certain requirements for sound quality and are willing to use dual channels, and if you don't have high requirements for 3D positioning in games, it is not bad. At most, its own hardware underlying implementation of EAX is worth mentioning.

APU (Audio Processing Unit) is directly connected to the CPU and CODEC to build a sound card (this technology is also used in XBOX). It consists of 5 DSPs, 3 fixed functions and 2 programmable. The hardware supports directx8.0 ! ! Self-built data transmission control architecture, not controlled by the south bridge. 2 programmable DSPs realize built-in 3D special effects (reverberation, echo, etc.), equalization (EQ), Dolby Digital (AC-3) and other algorithm functions. Programmable also means that these functions can be continuously upgraded with driver updates (as far as I know, this is a technology commonly used in high-end sound cards). Comprehensive hardware support for audio processing will greatly release system resources. But it still needs to be emphasized that it still needs Codec output, so Codec can still be found on the NFORCE2 motherboard .

SoundStorm is a further improvement on the SoundStorm standard. In fact, SoundStorm itself is a label that nVidia puts on motherboard manufacturers. As long as their nForce/nForce2 motherboards can provide comprehensive sound output using an integrated sound processor, with multi-channel capabilities - 6-channel analog output, S/PDIF digital output and AC-3 Dolby Digital sound quality, they can get it.

Reference address：Introduction to the sound card chip on the motherboard

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