<div><span style="color: rgb(160, 160, 168); ">On Sunday, September 23, 2012 at 2:04 PM, Ralph Giles wrote:</span></div>
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<span><div><div><div>On Fri Sep 21 16:31:21 2012, Stephen F. Booth wrote:</div><div><br></div><blockquote type="cite"><div>6.1: L R C LFE Ls Rs Cs (MPEG 6.1 A layout)</div></blockquote></div></div></span></blockquote><div><div>I should have been clearer with the labels I was using:</div><div><br></div></div><div>L = Left</div><div>R = Right</div><div>C = Center</div><div>LFE = Low frequency effects</div><div>Ls = Left surround</div><div>Rs = Right surround</div><div>Cs = Center surround</div><div>Rls = Rear left surround</div><div>Rrs = Rear right surround</div><div> </div><blockquote type="cite" style="border-left-style:solid;border-width:1px;margin-left:0px;padding-left:10px;"><span><div><div><div></div><div>Having read a bit more:</div><div><br></div><div>This matches the WAV (or USB) order if you map Ls (Left Surround?) to</div><div>Back Left and Rs (Right surround) to Back Right, instead of mapping them</div><div>to Side Left and Side Right as I do.</div><div><br></div><div>Practically, there's not much difference in what you call these for 6.1.</div><div>If you only have 7 speakers, the signals go to the surround speakers</div><div>regardless, and if you have 8, the matrix should send the surround</div><div>signals to both side and back speakers.</div></div></div></span></blockquote><div> I think that's true. I was using the nomenclature that Apple uses for Core Audio as that is what I'm most familiar with.</div><blockquote type="cite" style="border-left-style:solid;border-width:1px;margin-left:0px;padding-left:10px;"><span><div><div><div></div><div>I chose the 'Side' label over 'Back' based on the suggested ideal</div><div>placement diagrammes at sites like <a href="http://crutchfield.com">crutchfield.com</a> and <a href="http://dolby.com">dolby.com</a>, and</div><div>dolby's reference to the 'back surround' speakers in 7.1 as being the</div><div>extra ones, not the side speakers.</div><div><br></div><div>So the question is, how to choose between mapping surround to "side" and</div><div>mapping it to "left". Can you elaborate on "what Apple has done" and why</div><div>we should chose the other way?</div></div></div></span></blockquote><div>Apple doesn't actually force any channel orderings, so I may have been slightly unclear when I said that is what they have done. However, they provide a long list of predefined channel layouts provided by various groups- MPEG, ITU, DVD, etc. Apple lists the following ITU defined layouts:</div><div><br></div><div>1.0: <span class="Apple-tab-span" style="white-space:pre"> </span>C</div><div>2.0: <span class="Apple-tab-span" style="white-space:pre"> </span>L R</div><div>2.1: <span class="Apple-tab-span" style="white-space:pre"> </span>L R Cs</div><div>2.2. <span class="Apple-tab-span" style="white-space:pre"> </span>L R Ls Rs</div><div>3.0:<span class="Apple-tab-span" style="white-space:pre"> </span>L R C</div><div>3.1:<span class="Apple-tab-span" style="white-space:pre"> </span>L R C Cs</div><div>3.2:<span class="Apple-tab-span" style="white-space:pre"> </span>L R C Ls Rs</div><div>3.2.1:<span class="Apple-tab-span" style="white-space:pre"> </span>L R C LFE Ls Rs</div><div>3.4.1:<span class="Apple-tab-span" style="white-space:pre"> </span>L R C LFE Ls Rs Rls Rrs</div><div><br></div><div>Annoyingly, I can't find the ITU mapping for 6.1 although I think my suggestion from earlier is still reasonable. ITU 775-3 specifies some channel orderings (<a href="http://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.775-3-201208-I!!PDF-E.pdf">http://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.775-3-201208-I!!PDF-E.pdf</a>) but I couldn't find anything for 6.1 or 7.1. It may be in a different document I didn't find.</div><blockquote type="cite" style="border-left-style:solid;border-width:1px;margin-left:0px;padding-left:10px;"><span><div><div><blockquote type="cite"><div>7.1: L R C LFE Ls Rs Rls Rrs (MPEG 7.1 B layout)</div></blockquote><div><br></div><div>Here I just disagree. This is the same set of labels as in my proposal,</div><div>but the order does *not* match WAV order, assuming Ls->left side and</div><div>Rls->back left.</div></div></div></span></blockquote><div>You're correct in the meanings of the channel labels, but I actually mistyped and the layout should be called MPEG 7.1 C. I tried to pick the layout I thought was most in line with the other FLAC layouts.</div><div><br></div><div>Stephen</div><blockquote type="cite" style="border-left-style:solid;border-width:1px;margin-left:0px;padding-left:10px;"><span><div><div><div><br></div><div> -r</div></div></div></span>
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