thought HD was digital sound ???

[Stu123]

just read this in a forum and i thought the HD codecs were digital sound now im confused

Dolby TrueHD and DTS-HD MA compress the LPCM audio signals without any loss of original data in order to save space on a disc. When the saved signals are decoded and decompressed, we will get LPCM signals again.

If the disc player decompresses and decodes the compressed audio, it will send the LPCM signals to the receiver. The receiver will then covert the LPCM signals from digital to analog for playback through the speakers.

[Uniquely]

Exactly.... because your speakers can't play digital signals they MUST be converted to analog. It's always been this way... with DVD's, CD's or any digital source. Your receiver has DAC's (digital to analog converters) for this very purpose.

[Stu123]

Originally Posted by robinandtami

Exactly.... because your speakers can't play digital signals they MUST be converted to analog. It's always been this way... with DVD's, CD's or any digital source. Your receiver has DAC's (digital to analog converters) for this very purpose.

So they call it dolby digital but you're not really hearing digital? i need some fresh air

[Uniquely]

The source is indeed digital and "pure" but speakers are analog equipment. The digital signal must be converted to analog, but that does not mean that it is degraded or corrupted in any way whatsoever.

[syncguy]

Originally Posted by stubiedoo

So they call it dolby digital but you're not really hearing digital? i need some fresh air

Yes it is digitally recorded on the disk as opposed to analogue cassette tapes or vinyl records. The player plays back the digitally encoded (e.g. DTS HD-MA) bit stream and it is carried over HDMI cable on to the receiver. The receiver decodes (DTS HD-MA to PCM) and coverts (PCM) digital bits into an analogue signal (using a DAC) and feeds into the analogue amplifier and to the speakers. In principle it is a simple process. (In some cases the player decodes DTS HD-MA to PCM.)

[-Sandro-]

unless you can ear "0100111110110" sound from the speaker, yeah it's analog

[benricci]

Originally Posted by stubiedoo

So they call it dolby digital but you're not really hearing digital? i need some fresh air

There is no such thing as "digital" sound. Audio information can be stored in a digital format, but it needs to be converted to analog at some point so speakers can output sound and you can, you know, actually hear it.

[Stu123]

ok thanks guys

[bigm]

Originally Posted by -Sandro-

unless you can ear "0100111110110" sound from the speaker, yeah it's analog

I thought I was the only one!

[syncguy]

Originally Posted by stubiedoo

ok thanks guys

Welcome. Further, when digitally stored and transmitted the data is more robust than analogue storage and transmission. When it is digital (1 or 0), it is robust since it has to change from 1 -> 0 or 0->1 to introduce an error. Additionally digital error correction can be built in to the storage media so that if a bit is changed from 1->0, it can be detected and corrected - so it is robust than analogue.

[Afrobean]

Originally Posted by -Sandro-

unless you can ear "0100111110110" sound from the speaker, yeah it's analog

Actually, binary in sound form would probably sound like morse code except way more unintelligible. You wouldn't hear "one" and "zero", it'd be a tone or lack-of-tone.

[Jeff Kleist]

Ever hear a modem connecting? That's what binary sounds like in analog

[DIY_HD]

Sound itself is analog. Your eardrum acts as an analog to digital converter (ADC) which translates continuously variable sound data into electrical pulses in your auditory nerves. Your brain takes these pulses and interprets them as sound. Anybody know what the sampling rate of the eardrum is? Doesn't matter. . .

Digital audio begins with sampling analog input from microphones, etc, and records the level of each frequency at specific intervals measured in Kilohertz (kHz), or thousandths of a second. So a 24kHz sampling rate would record (or sample) an analog sound wave 24,000 times each second. In this process some analog data is lost, but if the sampling rate is high enough, you won't notice any loss of fidelity.

http://en.wikipedia.org/wiki/Samplin..._processing%29

So if digital audio is ultimately converted back into analog, why bother with digital? Why not just leave it in analog form? Primarily for noise elimination, but also for Digital Signal Processing (DSP). Your AVR has a lot of computing power which can modify the digital audio data in amazing ways to produce different effects, or "soundfields".

What you need to know is that the Digital-to-Analog conversion should only be done once, just before the signal is sent to the speakers. Multiple AD-DA conversions will introduce noise and degrade the signal quality.

Some of you may not be old enough to remember analog recordings on vinyl discs (the old black plastic records that you played on a turntable) and analog audio tapes, such as cassettes and 8-track tapes. These were notorious for producing lots of pops (when dust hit the phonograph needle) and hiss (from the tape dragging across the magnetic play head). These were unavoidable in the analog world, so they developed methods of reducing the noise, most notably using Dolby Noise Reduction technology. Yes, this is the same Dolby Labs which developed Dolby Digital and Dolby TrueHD audio. The digital revolution in sound began with Digital Audio Tape (DAT). Then came laser discs (about 8"), then Compact Disc (CDs, 5.25"), and now 4-layer Blu-ray (soon).

Here, in the technical vastness of the future, we have sophisticated digital audio processing equipment and technologies. These produce cleaner (virtually noiseless) audio signals which are so close to the original as to be considered identical (or better). Enjoy.

[Anthony P]

So they call it dolby digital but you're not really hearing digital? i need some fresh air

you can't hear digital, digital is just data information. Sound is a wave that travels through the air (or any other medium that can send the vibrations). For digital a snap shot is taken every few fractions of a second, how many snap shots is represented by the Khz, for example CD is 44.1, that means that 44100 snap shots are taken, for BD most (like DVD) are 48 (000), but some are 96 (000) and it can be 192 (000). The next thing is that if we think of the wave as
we measure how high it is at each of the points taken. This is where bit depth comes in. The higher the bit depth the more precise the measurement.

So we end up with something like

the grey wave represents the original sound wave and the red, the digital (PCM) values

Now those values (i.e. in that example, 0,4,5,4,3,4,6,7,5,3,3,4,4....) are what we call the LPCM (there are other methods but they are irrelevant to this discussion). Anything else will try and compress how much place is taken (for example if there is no sound coming from one speaker, why have 0,0,0,0,0), with lossy (DD,DTS...) sometimes it messes up those numbers (i.e. could become 0,4,4,4,3,4,6,7,5,3,3,4,4..,) with lossless they should be the same values. Either way once decoded we get LPCM again.

Now the DACs (digital to analogue converter) in your receiver (or BD player if analogue out is used) will take those values and use an algorithm and recreate a sound wave, that sound wave could (but won't) be exactly like the original that was digitized, then that analogue signal is sent to the speaker and the speaker membrane will vibrate and that vibration is sound.

[Anthony P]

Originally Posted by Afrobean

Actually, binary in sound form would probably sound like morse code except way more unintelligible. You wouldn't hear "one" and "zero", it'd be a tone or lack-of-tone.

yup, binary is using the two real states of electricity, either there is (on/1) or isn't (off/0). You would need to give it a tone for 1 and it could be anything, on the other hand it could also not be a tone, it can be electricity (normal cables) or light (fibreoptic) and they don't make sounds, so 1 or 0 would sound the same

[Tinman7783]

[QUOTE=Tinman7783;2338385]My receiver Sony STR-DH700 7.1 ch does DTS but technically not Dolby HD. I know DTS MA is backwards compatible and this explains why my Bluray movies with DTS MA sound amazing. My question is when playing Bluray movies with Dolby True HD my receiver display states dts 3/2.1 and it sounds great much better than regular Dolby Pro Logic, is this HD audio? To achieve this I make sure at my Bluray player LG BD 370 I choose the HD audio option. The receiver does 8 channel LPCM is this way? B/c all audio signals are converted to LPCM anyways?

ty "That's no moon it's a space station!!"