What is High Definition Audio?

SpinnerSpinner Birmingham, UK
edited January 2006 in Science & Tech
Hardware Secrets have posted a short article looking at High Definition Audio and what it can offer us.

View: What is High Definition Audio
Before HD Audio was released, on-board high quality audio was only available if your motherboard had a separated high quality audio controller – like Envy24 from VIA, for example. With HD Audio technology, the south bridge of the chipset produces high-quality audio itself, without the need of a separated controller chip, what would make the motherboard more expensive. The south bridge only needs an external codec (coder/decoder) chip to make the needed digital/analog and analog/digital conversions. This kind of chip is inexpensive compared to a “full” controller chip. One example of codec compatible with Intel’s HD Audio is C-Media 9880.
Source: Hardware Secrets

Comments

  • drasnordrasnor Starship Operator Hawthorne, CA Icrontian
    edited December 2005
    I found this article misleading. I came in thinking I'd be hearing about the latest and greatest formats for storage and playback of music and sound and find a pretty shameless plug for Intel's new marketing catchword for codec audio. What the author glosses over is that the "standard" Intel proposes is in fact proprietary and only found on Intel chipsets and functionally indifferent from the existing, universally-accepted AC'97 standard.

    It's nice that the chipset supports 192kHz, 32b sampling but so do many inexpensive sound cards these days. However, the actual sound quality you hear is determined by the digital-analog and analog-digital converters and the amplifiers attached to these circuits as well as the amplifiers in your speakers and the speakers themselves. Historically speaking, motherboard manufacturers have opted for the cheesiest codecs and wimpiest amplifiers money can buy with few exceptions; I seem to remember a motherboard a couple years back that had valve amplifiers on it, read: electron tubes. I see no reason for this trend of poor component specification to change. Also, never mind the fact that if you use digital speakers or are connected to your home theater receiver via S/PDIF your computer's sound hardware has absolutely nothing to do with the sound you hear anyway (DSP, decoding, and amplifier tasks are done by hardware in the speakers/receiver).

    The author then segues into a shameless Dolby plug. The first two "sound levels" are unacceptably poor for anyone that listens to something other than ground-shaking bass like rap, hip hop, or heavy metal or uses their computer's sound for the various activity noises only. Less than 95dB signal to noise ratio is easily audible noise at normal volume levels. Note that Analog Devices SoundMax codec audio found in many laptops and motherboards is rated for 95dB and in my opinion produces only acceptable levels of noise at reasonable volume levels.

    The upmixing the author refers to in the form of Dolby Pro Logic has been available for some time now, but lets face it, every time a signal goes through one of these filters you get distortion. That's the entire point of upmixing in the first place. A fairly smart digital signal processor (DSP) sends phase-shifted copies of the original signal to the different satellite channels (fronts, backs, and centers) and low-pass filtered combinations to the low-frequency channels (subwoofers). These phase shifted signals add together in the air and the combined total excites your eardrums. What you're getting is something that the author found pleasing but is in actuality a highly distorted reproduction of the original signal.

    If you don't understand terms like distortion, noise, SNR, THD, etc. I find this to be a good primer: http://www.ethanwiner.com/audiophoolery.html

    -drasnor :fold:
  • GHoosdumGHoosdum Icrontian
    edited December 2005
    Perhaps a more important question would be, Who is Kaiser Sose?
  • edited January 2006
    hi there i have a problem when i insret in any pc game it is askin for would you like to install c media high definition audio diver and if you go to no it dont intsall the pc game plese email me if u know how to fix it plz my email andress is junr_pezo@hotmail.co.uk
  • edited January 2006
    drasnor wrote:
    I found this article misleading. I came in thinking I'd be hearing about the latest and greatest formats for storage and playback of music and sound and find a pretty shameless plug for Intel's new marketing catchword for codec audio. What the author glosses over is that the "standard" Intel proposes is in fact proprietary and only found on Intel chipsets and functionally indifferent from the existing, universally-accepted AC'97 standard.

    It's nice that the chipset supports 192kHz, 32b sampling but so do many inexpensive sound cards these days. However, the actual sound quality you hear is determined by the digital-analog and analog-digital converters and the amplifiers attached to these circuits as well as the amplifiers in your speakers and the speakers themselves. Historically speaking, motherboard manufacturers have opted for the cheesiest codecs and wimpiest amplifiers money can buy with few exceptions; I seem to remember a motherboard a couple years back that had valve amplifiers on it, read: electron tubes. I see no reason for this trend of poor component specification to change. Also, never mind the fact that if you use digital speakers or are connected to your home theater receiver via S/PDIF your computer's sound hardware has absolutely nothing to do with the sound you hear anyway (DSP, decoding, and amplifier tasks are done by hardware in the speakers/receiver).

    The author then segues into a shameless Dolby plug. The first two "sound levels" are unacceptably poor for anyone that listens to something other than ground-shaking bass like rap, hip hop, or heavy metal or uses their computer's sound for the various activity noises only. Less than 95dB signal to noise ratio is easily audible noise at normal volume levels. Note that Analog Devices SoundMax codec audio found in many laptops and motherboards is rated for 95dB and in my opinion produces only acceptable levels of noise at reasonable volume levels.

    The upmixing the author refers to in the form of Dolby Pro Logic has been available for some time now, but lets face it, every time a signal goes through one of these filters you get distortion. That's the entire point of upmixing in the first place. A fairly smart digital signal processor (DSP) sends phase-shifted copies of the original signal to the different satellite channels (fronts, backs, and centers) and low-pass filtered combinations to the low-frequency channels (subwoofers). These phase shifted signals add together in the air and the combined total excites your eardrums. What you're getting is something that the author found pleasing but is in actuality a highly distorted reproduction of the original signal.

    If you don't understand terms like distortion, noise, SNR, THD, etc. I find this to be a good primer: http://www.ethanwiner.com/audiophoolery.html

    -drasnor :fold:


    Valve amplifiers are the choice of audiophiles world wide, I've seen $25,000 Macintosh valve monoblocks (that's 25 grand per monoblock and we're talking about a 50W Class A amplifier here) that had the most awe inspiring sound you can imagine. Musicians pay out the nose for valve head/stack combos. Just because it's old tech doesn't make it cheesy.

    For your information you find PRE-AMPs on motherboards that are capable of a wrms of less than 3v sustained. You'll never find a full blown amplifier on a motherboard as it would add unusual complexity to the board's build and the expense would be too high.

    I can't say that I disagree about the snr or the DDL points you address but slamming a motherboard manufacturer for using vacuum tubes to provide a warmer sound. Tubes are preferable to solid state components due to the way they handle distortion, a tube adds even order distortion when pushed to the point of saturation giving the sound a fuller tonality and a richer sound whereas solid state components add odd order distortion which ends up adding emphasis to the sound in a bad way making it sound harsh.

    This is why a small solid state amplifier when pushed too hard into speakers that aren't going to break up will make soundforms that make you cringe. The midrange sounds harsh and metalic, the treble has a harsh sizzle and the bass gets soft.

    Kinda sounds like what you experience when you overdrive the sound on a PC by cranking up the sound on the PC and turning the speakers down to compensate doesn't it? With a tube pre-amp you'll notice that the soundform becomes smoother rather than spikier when overdriven. This means that it's more pleasing to the ear, doesn't make baby jesus cry and is less likely to be noticed.
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