TVs & Home Theaters forum

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H.D.M.I. AUDIO COMPRESSION

by stewart norrie / September 7, 2006 9:13 AM PDT

I just asked a home theater expert what difference would there be using h.d.m.i. to your Amp Vs using optical audio connection. And was told the audio from h.d.m.i. would be compressed and sound quality would be slightly better using optical audio I was also told that h.d.m.i. 1.3 would correct this. Also would running h.d.m.i. thru amp then to t.v. degrade picture quality? I run all my vidio straight to t.v. and all audio to amp using optical cables and this set up really works great anyway beautiful day here in San Jose have a nice day all stewee

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Find a new expert
by breslin / September 7, 2006 12:37 PM PDT

Stewee,

A properly designed HDMI device will not compress the audio. You should not hear any difference between a HDMI connection to your receiver and an optical (or coaxial) connection.

If your receiver will switch HDMI you have the advantage of not needing to switch the input on your TV and your receiver, switching inputs on the receiver will do both audio and video. If your receiver will also switch and convert s-video, composite and component inputs to HDMI your connections can be even simpler.

Again, if the HDMI is implemented properly there will not be any degradation in picture quality either.

HDMI 1.3 will allow for greater bandwidth which will allow for new higher bandwidth protocols but nothing in use in any receiver today will be affected, or needs the additional bandwidth that 1.3 allows.

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Mr breslin Thank you
by stewart norrie / September 7, 2006 1:22 PM PDT

There are two reasons I run all my vidio and audio seperretly #1 with 5 remote controls my roomates cannot even turn the darn thing on #2 Iam able to fine tune all anolog sourses seperetly. v.c.r. and old pioneer lazer disk player. Or you could just give me your scaller ha ha. have a nice day stewee

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Yes, find a new expert!!!!
by jcrobso / September 8, 2006 12:45 AM PDT

Opticial digital and HDMI digital are just transmission lines! They are both designed to carry the signal WITH OUT CHANGING IT!
Digital eather works or it dosen't work.
Running HDMI thru a AV reciver affect video Quality? Same answer. It's all about the bits. John

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Pulse Code modulation
by inni121 / September 8, 2006 1:13 AM PDT

that is how these cables send date over to the receiver from any audio source

basicaly it is a digital representation of the analogue signal, its a 20-bit (24 max) signal sampled at either 48 KHz or 96KHz depending on the source (toslink is 2-4 channels).

that is at least how optical Digital transmisison cables work

HDMI on the other hand sends uncompressed digital audio and video signals together (up to 8 channels for audio after HDMI 1.2) the audio is 1-bit same as SACD so the quality is better

quantization distortion is what HDMI is not supposed to have by not sending a compressed data stream u dont loose any bits of data

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Pulse Code modulation
by jcrobso / September 8, 2006 1:39 AM PDT
In reply to: Pulse Code modulation

Yes don't drop any bits!!!!!!!
Yes, in therory the SCAD is better than PCM.
If both casses we get back to quality of the source material and how well it was recorded and processed and how much compression was used BEFORE it was put on the DVD. John

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Toslink, Coax, and HDMI can all transmit uncompressed signal
by breslin / September 8, 2006 1:40 PM PDT
In reply to: Pulse Code modulation

Toslink, Coax and HDMI are ways to carry a digital signal, all of these connection types can transmit uncompressed signals. A standard CD is uncompressed.

The extra band width with HDMI 1.3 may enable even higher bandwidth in the future but any of the three should handle any of the currently used codecs, compressed or not, just fine.

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compression quality
by inni121 / September 9, 2006 5:33 AM PDT

i think that even if the HDMI Bandwidth is much higher than coax or toslink, it cannot be taken advantage of id the amplifier BW is smaller ot the actual speaker that produces the sound cannot take advantage of the higher BW (20Hz-20KHz)

i am also wondering about MP3 compression, at around 320 kbps would you still be able to tell the difference between MP3 and CD quality? as far as i know SACD is twice the quality of a CD ??? duno for sure i think they are sampled at 96KHz

and if u were to play high quality music off the PC trough a toslink cable, would it sound like SACD ???

basically the music is as good as the recording thats for sure, no matter the cables

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