DTS-ES and no surround back speaker



<font color='#000000'>What happens to the surround back channel signal when I'm watching a 6.1 DTS ES movie and I have the surround back speaker set to &quot;no&quot;. Is the information matrixed into the surround left and right?</font>


<font color='#000000'>I think down mix is the word, the sixth channel (rear centre) will be down mix into Left &amp; Right Surrounds</font>


Audioholic Chief
<font color='#000000'>Hi
I think both of you are correct
It will be mixed into the L/R surround and other channels depending on your processor. And it will be
&quot; down mixed&quot; because it is a discreet channel</font>


<font color='#000000'>You are both kinda right but still wrong.

If you play it back through a receiver that lacks a dts-ES decoder, then you it will just play back the normal 5.1 channels. The 6th channel is matrix-encoded into the two surround channels on all dts-ES discs (whether &quot;discrete&quot; or 'matrix&quot;). A &quot;discrete&quot; dts-ES disc also contains the 6th channel stored in the extended data of the dts stream (ignored by a non-dts-ES decoder). A dts-ES discrete compatible decoder will use this as the surround back channel instead of trying to decode it out of the two surrounds. It still has to remove the surround back channel from the two surround channels. Look at www.dtsonline.com for more information. So, it is not actually mixed or down-mixed into the rear speakers; it is just not extracted from them in the first place. A subtle but important difference.

If you play it back on a dts-ES compatible receiver with 6.1 decoding turned off, then it will be just like the above case. A Sony receiver with DCS can decode the 6th channel and create a &quot;virtual&quot; speaker. This tricks your ears/brain into hearing the sound as coming from behind you (which not as simple as mixing the 6th channel into the two surrounds!). It works quite well, and even though it is still a 5.1 speaker setup, it sounds better than a plain old 5.1 source.</font>


<font color='#000000'>AaronB,

I have gone and done the DTS website reading and as a result, in conjunction with the other threads on the SONY STR-DA4ES, I'm wondering what the reality and marketing is with respect to DTS as a specification and manufacturers such as Sony.

DTS seems clearly to indicate that its a 5.1 and 6.1 system.
Sony indicates their 4ES unit can 'decode 7.1 source' - though it goes into no detail and I cannot find any availability of 7.1 sources.

Is Sony's claim at decoding 7.1 sources most likely just marketing on their part which results, in the end, in just a unique way for them to present 5.1 and 6.1 source material?

Certainly mapping the SL and SR signals to the RL and RR outputs provides a way to use 5.1 signals on a 7.1 amp system in a unique way. &nbsp;Likewise sending the Rear signal to both RL and RR channels provides for a way to use 6.1 material - even matrixing in the SR and SL signals in combination with the Rear into the RL and RR of the 7.1 hardware. &nbsp;

However, is there any specification definitions of 7.1 source encoding? &nbsp;If I consider my 10 year cycle of equipment replacement, and there is not likely to be any 7.1 source, or that 7.1 is just a marketing thing, then it may be indeed the case, that a 5.1 or 6.1 system will be more than sufficient for any home theater needs.</font>


<font color='#000000'>This is from the document at http://www.dtsonline.com/history8.pdf
<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> The other algorithm used by DTS, Coherent Acoustics, ((AaronB: i.e. Coherent Acoustics is the algorithm used for Home Theatre, which is different than the one used for Cinemas)) is highly scalable and can operate anywhere in the range 32 kbit/s to 4 Mbit/s. It can handle up to 24 bits, and up to eight channels. (The decoder population implements 5.1 channels.) Again contrary to popular assumption, Coherent Acoustics is not a perceptual coder at the data rates used on CD, LD, or DVD. When operating at lower bit rates, the perceptual techniques are enabled.

Here, they refer to the algorithm supporting eight channels (I assume this means 7.1, but it may mean 8.0 as well). The first decoders supported 5.1 channels. Currrent dts-ES discrete decoders certainly support 6.1 (7?) channels, but they may also support 7.1 (8?) channels. I don't know the implementation used for dts-ES discrete decoders, so I can not directly answer whether the 4ES can decode a dts 7.1 format. I don't think that any dts 7.1 source material is available commercially.

I also found it interesting that the paper states that perceptual coding is not used for data rates for &quot;CD, LD or DVD&quot;, but it is used for &quot;lower bit rates&quot;, which actually refers to the majority of dts soundtracks out there on DVD (i.e. DVD's which contain both multichannel DD and dts soundtracks) which are at half the original DVD data rate, 754 kbps.</font>
<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>
GermanMan : <font color='#000000'>However, is there any specification definitions of 7.1 source encoding?</font>
<font color='#000000'>Considering that the current theatre equipment only supports up to 6.1 (and even that looks like a recent &quot;punt&quot;), I would say that we're in for quite a bit of time before 7.1 DTS discs become &quot;all the rage&quot;, even if the spec does support it.</font>

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