Difference between HD Audio and AC97
March 10th, 2010Preface:
User might have a lot of time in the planning of the host platform, audio will be required, but refer to AC'97 and HD Audio, probably only touched like passing. So what exactly is AC'97 and HD Audio What's the difference then? They Who better? How do we distinguish between going to choose? I believe even some “fields and then” in the face of this problem is difficult to Dachu it herself.
Recently, we have collected a lot of information on the HD Audio, organizers and adds to our analysis written dedicated to everyone so that everyone on this new audio standards can have a comprehensive understanding.
First of all, let's look at what is AC'97, what is HD Audio.
What is the AC'97:
AC'97 is based on Intel's five computer makers, led by Intel, Creative Labs, Analog Device, NS, and Yamaha, in June 1996 jointly developed an audio standard, known as the Audio Codec'97 technical standards, referred to as AC'97, means “audio digital signal encoder / decoder.”
Why are there AC'97:
ISA sound card because of the early integration is not high, spreading a large number of components on the sound card, and later as the technical and technological level of development, there has been a single chip, sound card, only one chip can be completed for all of the features sound card. However, due to sound card of the digital part and analog part of the integration, it is difficult to reduce electromagnetic interference to the analog part of the impact of signal to noise ratio makes the ISA sound card is not satisfactory.
AC'97 specification is characterized by the double-integrated structure, is divided into Digital Controller (digital signal controller) and the Audio Codec, so that ADC (Analog-to-Digital Converter, analog / digital converter) and DAC (Digital-to-Analog Converter , D / A converter) into a separate module called the “Audio Codec” (multimedia digital codec) and a small chip, while the sound card's main chip, the digital part has become known as a “Digital Control” ( Digital Signal Controllers) large chip (that is, an integrated I / O control and the main DSP chip). As much as possible to reduce EMI (Electro-Magnetic Interference, electromagnetic interference) effects, while the Digital Controller and Audio Codec through the AC-Link connection (independent sound card may be used to connect I2S).
To reduce interference and to reduce costs as the goal of the AC'97, its sound framework for the definition of terms, has not only confined to a small Codec went, from the sound card industry, the impact of the whole point of view, it is progress The. When the cost advantage of the characteristics of applications in the soft-board sound card when the advantages to be larger. This is the AC'97 sound card can be quickly replaced by an independent and become a sound industry, a necessary condition for the absolute supremacy.
Will be the same as the integrated AC'97 sound card is a misunderstanding
Motherboard sound card would be the soft part of the Digital Control of the hardware completely omitted, and their work exclusively through the driver allows the processor to complete, this will become a necessity for an integrated sound card to reduce costs, and this is the motherboard AC'97 soft sound card implementations. Later, due to the popularity of an integrated sound card, AC'97 almost be regarded as equivalent to an integrated sound card, this is actually a misunderstanding.
What is HD Audio:
HD Audio or High Definition Audio, which means high-fidelity audio. As an IT industry's first widely specification, AC'97 in the face of the new DVD-Audio, SACD multi-channel high-quality music encoding a bit old, though carried out three major version upgrade but still appears to Heart but more than enough power. In order to change this situation, April 15, 2004, Intel and the rest of the world a 80 enterprises have developed a new standard, developers, code-named Azalia, standards were introduced soon after changed its name to HD Audio. HD Audio with high flexibility, mobility, low cost, high-stability characteristics, and allow ample space for the upgrade, all will be able to make it spread rapidly.
HD Audio implementation method:
HD Audio and AC'97 way to achieve and not very different, there is no real sense of the HD Audio independent sound card. This is a look at the on-board sound card, HD Audio and AC'97 overall structure is almost exactly the same, the data is still part of the processing to the processors. Let's take a look at where the progress of HD Audio.
Posted by deanhayes1968