Any difference in audio quality between signals carried on HDMI & Optical

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tellranga

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Friends,
Through this forum, got very good knowledge to buy my Onkyo receiver, LCD TV, DVDP & Voltage stabilizer. Thanks to all for your valuable suggestions.
Still HDMI cable / Optical cable is pending to complete my HT setup. Please suggest me which combination will give best SQ & PQ.

Option 1
For Audio and Video
  • HDMI cable from Xtreamer to Onkyo receiver +
    HDMI cable from DVDP to Onkyo receiver +
    HDMI cable from Onkyo receiver to LCD TV.(3 HDMI cabes required)
  • Overall cable count
count of HDMI cable -3
count of Optical cable -0​

Option 2
For video
  • HDMI cable from Xtreamer to LCD TV +
    HDMI cable from DVDP to LCD TV (2 HDMI cables required)
For audio
  • Optical cable from Xtreamer to Onkyo Receiver +
    Optical cable from DVDP to Onkyo Receiver(2 Optical cables required)
  • Overall cable count
count of HDMI cable -2
count of Optical cable -2​
In Option 1, HDMI cable is responsible for both audio & video.
Myth 1 - Eventhough HDMI cable is meant to carry both audio & video, in reality it will be overloaded and one has to compromise slightly in PQ.
Whereas in Option 2, HDMI cable is responsible only for video and Optical cable is responsible only for audio.
Myth 2 - Here since we have dedicated HDMI & Optical cables for video and audio, PQ & SQ will be far better that option 1.
My question,
  • Are there any difference in audio quality between signals carried on HDMI, & optical cable.
  • Please suggest me which combination will give best SQ & PQ.

thanks,
ranga.
 

skumar

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Assuming a bug-free implementation of both the optical out and HDMI out on your XMP and DVDP and decent quality cables, AQ via HDMI and optical should be the same.

However, HDMI cable will enable you to listen to lossless audio when you get such content in the future.
 

spirovious

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+1 to that,but remember ,with optical cable,signal is converted & passed in optic ray & again converted to digital @ AVR level.
This convertion can degrade the SQ.If think of SPDF coax& good cables can come close to HDMI>
 

santhosh

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Like skumar and spirovious has already mentioned. For movies, HDMI is the way to go if your AVR is HDMI capable.

HDMI has enough bandwidth to carry both HD video and lossless audio using one single cable. Using HDMI, then you are better off using HDMI as you will be able to enjoy lossless audion formats like DTS MA HD and Dolby Tru HD. Next firmware of Xtreamer should allow you to enjoy the lossless formats through your receiver.

In my case, my AVR is not HDMI capable. So I use HDMI from xtreamer and PS3-slim to get video. For audio, I use optical cable which forces xtreamer and PS3 to downmix the audio to DTS 5.1 and Dolby 5.1. In order to enjoy the lossless audio formats in 7.1, I need a new AVR or a 7.1 pre-processor.

Also, digital coaxial is said to be marginally better than optical for audio quality but xtreamer does not provide this option.
 

nitinbose

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There are Blu-ray players with analog 5.1/7.1 outputs, what if we used these for the audio connection from the player to the AVR while an HDMI cable for the video connection? Would there be any degradation in the audio quality?

I've heard unconfirmed romours that analog outputs on the blu-ray player (5.1/7.1) often give audio at much lesser quality than the original audio - which is to combat piracy.

Any truth in this?

regards,

Nitin.
 

madbullram

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Analog connection has many variables, for example the Cable quality is a BIG differentiator which makes the SQ good or bad. With the right cable, you might infact feel the analog one marginally better than HDMI.

With HDMI as long as your cable is 1.3a/b/c compliant you will get the same SQ as any cable(irrespective of cost or brands) so its always a safer bet. Plus no cable clutter etc, simple one cable for audio and video.

The piracy part is pure myth!
 

skumar

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There are Blu-ray players with analog 5.1/7.1 outputs, what if we used these for the audio connection from the player to the AVR while an HDMI cable for the video connection? Would there be any degradation in the audio quality?

I've heard unconfirmed romours that analog outputs on the blu-ray player (5.1/7.1) often give audio at much lesser quality than the original audio - which is to combat piracy.

Does this mean that BDPs route ONLY the non-HD DD/DTS tracks thru their Analog ports? Don't we have DACs that process HD signals into Analog out in BDPs?

If only DD/DTS audio is processed by DACs in BDPs and HD audio can only be routed thru HDMI, it makes sense from the Piracy angle. Somebody...
 

spirovious

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Does this mean that BDPs route ONLY the non-HD DD/DTS tracks thru their Analog ports? Don't we have DACs that process HD signals into Analog out in BDPs?

If only DD/DTS audio is processed by DACs in BDPs and HD audio can only be routed thru HDMI, it makes sense from the Piracy angle. Somebody...

BDp(with 7.1 out) can output all aud format via ana OR HDMI with BDp setup.
say- Pany BD80 has high Q DAC which can process HD aud to get 7.1ana out.
 

ajinkya

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Cranky,
I think Spirovious was talking about physical layer conversion of the signal...from electricity to light and back again, as opposed to coaxial which is electricity all the way. The transmission is ones and zeros, as you mention, but the physical carrier is optical is light, from my understanding.

-Jinx.
 

marsilians

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Cranky,
I think Spirovious was talking about physical layer conversion of the signal...from electricity to light and back again, as opposed to coaxial which is electricity all the way. The transmission is ones and zeros, as you mention, but the physical carrier is optical is light, from my understanding.

-Jinx.

Coax also requires conversion but toslink requires 2 additional ones.
 

subhash

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on comparing the spdif to hdmi
i found the SQ was better with hdmi
it was much smoother and cud be taken to realy loud levels ,maintaining the same smoothness in sound, with spdif @ loud leves it did tend to become harsh

loud levels = 3/4 the vol of the amp
 

psychotropic

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but would this impact sound quality? digital is digital right? especially when it comes to transmission, when there's no conversion/sampling involved?

Cranky,
I think Spirovious was talking about physical layer conversion of the signal...from electricity to light and back again, as opposed to coaxial which is electricity all the way. The transmission is ones and zeros, as you mention, but the physical carrier is optical is light, from my understanding.

-Jinx.
 

allajunaki

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They can carry DD/Dts 8ch(not in PCM form)

@Cranky- converted meens transmitted with optical ray,so there must be 2 stages rather than singal path.

Optical and Coax can carry DD / DTS of 5.1 CH. not the 7.1 Variety found on Bluray (there is not enough bandwidth on either to carry full HD audio, either in bitstream or as PCM signals)

There is no conversion. Optical is in fact, still in digital domain. So there is no signal degradation.

Infact, in optical cable, one can either "bitstram" DD or DTS or send 2 channels in PCM format.
 

ajinkya

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There is no conversion. Period.
Conversion (n):
1. the act or process of converting; state of being converted.
2. change in character, form, or function.

Cranky,
I think we're only arguing on semantics here. The "physical form" of the signal is converted - from electricity to light - so it is "converted" or transformed, even by the dictionary definition. The information in the signal is not changed, I agree, since the content is preserved without distortion.

And the velocity of EM waves is dependent on the medium of propagation. I doubt they will have the same value through optical cable as through copper/metal. But I will have to refresh my equations before I commit to that.

-Ajinkya.
 

allajunaki

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Like Cranky said, There will not be any loss of quality when u transmit in digital domain, unless there were something like this

Analogue -> Digital -> Digital -> Analogue
CL NTL CL

CL = Conversion loss
NTL = No Transmission Loss
CL = Conversion Loss


However, when transporting Audio, either via HDMI OR vis Optical OR via Co-ax

Digital(player) -> Digital(opti) ---> Digital(opti) -> Analogue(speakers)

You see in digital transmission if you send
1011 from one end, you receive it as 1011. If you dont, you lose the audio packet. And there wont be any sound or "pops" and "cracks". If fact, if im not mistaken, OPtical should be doing some sort of CRC checks, to ensure the last recived packet is not corrupted (else drop the packet).
You will NOT have cymbals less pronounced or Sound losing its contrast. The situation is even more interesting when it comes to DD or DTS, since the audio packets themselves are digital again (contains mathematical equations to hint the amps which sound is louder, and which channels to direct a particular sound to)
Have you noticed that if you make a copy of ur fav MP3 file to ur friend, it sounds identical (if both have same PC, with same settings ofc)? Simply because there is no loss of bits in a digital copy (we are performing a digital copy here, only difference is we are streaming bits).

As for sound differences between HDMI and optical. Its simply because HDMI can transport much higher bits, I believe HDMI can do 24bits / 96Khz where as optical can at best do 24bits /48Khz (Video DVDs are in this format).
However, if you were using Video DVD's audio via optiacal and HDMI, in theory they should sound the same. Practically they might sound different simply because of the way the audio processor converts them back to analogue.
 
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