# Hdmi vs optical cable audio passthrough.



## fiezdude (Jan 28, 2014)

Hey guys. What would be your opinion? A hdd media player with both optical n hdmi outputs. Should i be comfortable with the audio from the hdmi port or should i assign audio only through the optical cable? Which would be superior if applicable.


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## tonyvdb (Sep 5, 2007)

If your media player does the HD audio formats HDMI is the only way you can hear them.


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## fiezdude (Jan 28, 2014)

Ok so that means optical cables do not really have passthrough for multiple channels and sound effects?


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## prerich (Mar 26, 2008)

fiezdude said:


> Ok so that means optical cables do not really have passthrough for multiple channels and sound effects?


Opitcal can passthrough multiple lossy channels and sound effects, but it can't passthrough lossless codecs such as DTS-HD MA, TrueHD, and multichannel lossless PCM.


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## 3dbinCanada (Sep 13, 2012)

The optical cable will only pass the lossy Dolby Digital and DTS signals while HDMI will pass Dolby TrueHD and DTS-HD Master along with lossy Dolby Digital and DTS signals. In other words, the optical cable won't pass the high def codecs.


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## jason1234567 (Apr 11, 2014)

I'm kind of confused here... i have an optical cable from my Tv to my receiver so anything played through my Tv goes through the receiver... Now am i losing sound quality when i play a bluray or Dvd?


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## littlejohn74 (Feb 11, 2014)

jason1234567 said:


> I'm kind of confused here... i have an optical cable from my Tv to my receiver so anything played through my Tv goes through the receiver... Now am i losing sound quality when i play a bluray or Dvd?


Are your sources plugged into your AVR? or your TV?

Usually, you would want your AVR to be the heart of your system.
ie.

Source (BluRay) --> AVR --> Display (TV)

Some of the older TV's don't have the Audio Return Channel (ARC) enabled on the HDMI port so you have to bring audio back to the TV (for tv programs) back to the AVR via RCA or optical (like what yo've done). But if your sources a plugged directly into your AVR via HDMI, then you should be getting the good stuff.

General rule of thumb. Used HDMI where possible.


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## chashint (Jan 12, 2011)

Which HDD media player do you have (are you considering) ?


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## 3dbinCanada (Sep 13, 2012)

jason1234567 said:


> I'm kind of confused here... i have an optical cable from my Tv to my receiver so anything played through my Tv goes through the receiver... Now am i losing sound quality when i play a bluray or Dvd?


DVD, no. Bluray yes. Bluray contains the lossless codecs, Dolby TrueHD and DTS-HD Master which is only transmitted though the HDMI interface of your BluRay player and not optical. If you are playing BluRay, then you are getting the lossy codecs DTS and Dolby Digital which are also contained on the BluRay. Personally, I only hear subtle differences at best between the lossy and lossless codecs.


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## tonyvdb (Sep 5, 2007)

Actually if you are hooking up everything to the TV first and not through the receiver even DVD will be only 2.1 Dolby digital as TVs are not allowed to pass through audio with more than 2.1 channels.


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## gazoink (Apr 17, 2013)

tonyvdb said:


> Actually if you are hooking up everything to the TV first and not through the receiver even DVD will be only 2.1 Dolby digital as TVs are not allowed to pass through audio with more than 2.1 channels.


I've got an older Panny that passes 5.1 out via optical. Does that count?


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## appo1999 (May 12, 2013)

After spending an hour trying a number of cable configurations I have concluded that:

1 Optical 'toslink' will pass 5.1 but not 6.1 or 7.1 or higher
2 ARC via Hdmi will pass 5.1 but nothing 'higher' also

your mileage may vary but these are my results

Hdmi 'splitters' overall don't work at all.... (unless you spend big bucks) but this one works acceptable from parts express: HDMI Super Slim 4x2 True Matrix IR Compatible $85 ..... needs to be 'reset' often, has overly bright blue leds, but has excellent picture quality and passes 7.1 lpcm just fine... my cable length is 26 ft no problems


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## tonyvdb (Sep 5, 2007)

gazoink said:


> I've got an older Panny that passes 5.1 out via optical. Does that count?


A player or TV?


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## gazoink (Apr 17, 2013)

tonyvdb said:


> A player or TV?


TV...sorry.


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## tonyvdb (Sep 5, 2007)

You can try but it still won't pass any of the Uncompressed audio formats.


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## gazoink (Apr 17, 2013)

tonyvdb said:


> You can try but it still won't pass any of the Uncompressed audio formats.


Actually, what I'm saying is, it does work. Right, none of the "new" audio formats, but all the basics work just fine.


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## prerich (Mar 26, 2008)

gazoink said:


> Actually, what I'm saying is, it does work. Right, none of the "new" audio formats, but all the basics work just fine.


well everything is working correctly then. Toslink will not carry the new audio codecs, you will have to use HDMI or have them decoded in your player, then sent out as Lpcm via 7.1 analog outs.

Sent from my iPad using HTShack


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## gdstupak (Jul 13, 2010)

optical ability:
it can pass surround sound lossy (i.e. DD, DTS)
it can pass up to 2.0 lossless high resolution (i.e. flac 24/96)
it cannot pass surround sound lossless high resolution (i.e. Dolby TrueHD, flac 5.1 24/96)


optical output from TV:
TV's are allowed to pass any quality that is suitable for optical
TV manufacturers decide whether to limit/restrict capabilities (I don't know why many restrict it to 2.0 or 2.1)


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## 3dbinCanada (Sep 13, 2012)

gdstupak said:


> TV manufacturers decide whether to limit/restrict capabilities (I don't know why many restrict it to 2.0 or 2.1)


I think the reason is that TVs only have two speakers and why put in a 5.1 or 7.1 decoder for two speakers? Also, a lot of the channels only carry two channel information.


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## gazoink (Apr 17, 2013)

3dbinCanada said:


> I think the reason is that TVs only have two speakers and why put in a 5.1 or 7.1 decoder for two speakers? Also, a lot of the channels only carry two channel information.


All TVs made for the USA market must be ATSC compliant. The ATSC standards for audio are Dolby Digital AC3, which has capability of 5.1 channels, and built-in down-mixing to 2 channels. All TVs have to decode the AC3 stream just to drive built-in speakers. But they will use the downmix function to get two channels. 

However, none of that prevents a TV from providing a copy of the original AC3 multichannel stream to the optical/digital output, or shoved backwards down HDMI via ARC. No decoding required.

The limitations in what can be sent via optical are it's bandwidth, limited to 5MHz with plastic fiber. That puts the practical limit at 7 channels for 16/44, but just over 4 for 24/48, and a hair over 2 for 24/96, none of which will work for any high-rate multi-channel bitstream. However, Dolby Digital AC3 at 5.1 channels fits in 5MHz just fine.


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