What is HD Audio?

I installed the latest Realtek driver but did not notice any difference in sound from my Sony headphone (MDR 7506).

 

high-definition (HD) audio is lossless audio available on Blu-ray. the two dominant formats are DTS-HD Master Audio and Dolby TrueHD. both provide exception audio fidelity far beyond the specs of regular DTS and Dolby Digital.

 

Far beyond in what regard? Dynamic range, frequency response or both? Do you have any detailed specs on the differences from the older DTS and Dolby Digital?

Gary

 

HD audio is 24 bit sound playback. With most computers I've seen by default 16 bit audio is on, not 24bit, as 24 bit audio on CAN cause imcompatibilities with older software (though I've never seen it). Some people can hear a difference.. I don't notice much of one.

To turn on 24 bit audio, right click on your speaker icon by the time and click "playback devices". Highlight the playback device that has a checkmark on it and click 'properties'. Go to the 'advanced' tab, and select "24 bit, 44100 hz (studio quality)". If you have any audio errors or anything, the first thing to do would be to turn this setting back to its default.

 

in raw number form the differences are:

- DTS: 24 bit, 96 kHz, 1.5 Mbits/s
- DTS-HD Master Audio: 24 bit, 192 kHz, 24.5 Mbits/s

- Dolby Digital: 24 bit, 48 kHz, 448 kbits/s
- Dolby TrueHD: 24 bit, 96 kHz, 18 Mbits/s

both lossless formats support many audio channels. currently, the Blu-ray spec is limited to eight (8) audio channels.

 

DTS is also 24 bit so there should be no real difference in dynamic range from the newer HD Audio. I think Dolby Digital is also 24 bit. On a computer I'd be VERY surprised if anyone can hear the difference between 24 bit and 16 bit audio, because the analog portions of the sound card in most computers isn't that pristine in the first place.

The number of bits per sample only affects the difference between the loudest sound and quietest one and the number of variations between them. See this article: Quantization, Sample Rate, and Bits Per Sample or this one What are Sampling Rate and Bits per Sample?

8 bits provides 256 discreet steps, 16 bit provides 65,535 and 24 bit has 16,777,216. The question then becomes, is the analog audio circuit in your computer able to really produce the minute variations in db level to match 16 million discreet steps?

Gary

 

DTS and DD supports 24 bit masters, yes. the audio fidelity is much, much better with DTS-HD MA and Dolby TrueHD.

anyways, with standard headphones or speakers on the Sony FW you will not notice the difference between lossy and lossless audio. i would guess the Realtek driver would only make a difference if you send audio across HDMI to a home theatre setup.

 

Thanks for the detail instruction here.

I thank all other responses for taking the time to explain it.

I rip all my cd's in FLAC, I guess I cannot take advantage of this HD Audio?

 

Since they are all 24 bit formats the differences are no doubt due to the increased sampling rate. I am confused though on the bits per second numbers you posted.

- DTS: 24 bit, 96 kHz, 1.5 Mbits/s 24 x 96000 = 2,304,000
- DTS-HD Master Audio: 24 bit, 192 kHz, 24.5 Mbits/s 24 x 192,000 = 4,608,000
- Dolby Digital: 24 bit, 48 kHz, 448 kbits/s 24 x 48,000 = 1,152,000
- Dolby TrueHD: 24 bit, 96 kHz, 18 Mbits/s 24 x 96,000 = 2,304,000

My calculations are, of course, for just one channel. I am guessing the numbers you posted for DTS-HD and TrueHD are multi channel numbers. But I don't understand the ones you posted for DTS and Dolby Digital. They seem understated.

Gary

 

So what is CD music encoded in? Altho I use FLAC, but what go in comes out the same. Does it mean I have to buy some HD Audi CD's?

 

CD music is 16 bit

 

when talking about 24 bit with respect to compressed audio formats we should clarify that this does not imply the entire track is encoded at 24 bits per channel. DTS and DD encoding dynamically allocates how many bits are required to represent a given frequency. although DTS and DD support master audio tracks there were recorded at 24 bits this does not necessarily mean that DTS and DD are 24 bit.

my apologies. perhaps this will clarify a few things:

- the DTS figures i posted are at the highest end of its spectrum. the vast majority of DTS tracks are 754 kbits/s whereas DD tracks are 448 kbit/s. it's important to keep in mind, however, that higher kbits/s does not necessarily mean better quality because Dolby Labs uses different compression techniques than Digital Theatre Systems.

- multiplying the bit depth by the sample rate isn't an accurate means to gauge audio quality. DTS and DD are lossy formats and they are encoded very differently.

- when you take the master PCM audio track and transform it into DTS or DD, data is removed. ideally, the stuff that gets thrown away is audio that's beyond the range of human hearing or frequencies that are masked by other frequencies in the track. although Dolby Labs and Digital Theatre Systems uses very clever perceptual encoding / compression techniques the audio is still, in truth, not as good at the original PCM master.

- DTS-HD Master Audio and Dolby TrueHD audio are lossless formats that are, bit-for-bit, identical to the original PCM master.