[vorbis] Re: Calling for 5.1 Mastering experience! (vorbis ambisonics and 5.1)

[Christian HJ Wiesner]

Hi all, Hi Gregory,

is there any progress on the surround encoder in Vorbis been done 
recently  ?

Christian

<p>ChristianHJW wrote:

> Gregory Maxwell wrote:
>
>> I've been doing a fair amount of work with Vorbis support for 
>> Ambisonics,
>> which seems to be going along nicely. It seems that there is signifant
>> interest in coding 5.1 material with Vorbis esp as tarkin becomes more
>> complete, so I've decided to take a break from pure ambisonic work to 
>> look
>> into this.
>
>
> Great to see there is work done on Vorbis 5.1 !!! Latest AAC encoders 
> were slowly taking Vorbis position in the DVD backup scene, because 
> AAC 5.1 sounds quite nice at 200 - 240 kbps.
>
> About your question :
>
> From an sound engineering perspective, a separate subwoofer channel is 
> more or less useless, it could be muxed fine into the main Left and 
> Right speakers, resulting in a 5.0 setup.
>
> Never mux the signal into all channels, especially not the rear 
> channels, as those speakers are normally
>
> - not built to be able to generate low frequency stuff at all
> - will act against the output of the main speakers, unless you inverse 
> the phase by 180° , at least in a finite space = room. If you do 
> inverse, to sum up the bass output from rear and front speakers, be 
> sure there are a couple of setups where the 'rear' speakers are placed 
> somewhere in the room where they found space, but not really in the 
> rear, giving you problems again ;-) ...
>
> About 5.1 vs. 5.0 again :
>
> Only in very small rooms, where low frequencies can not even match the 
> lambda/2 criterium from one wall to another ( again : finite space = 
> room problem ) it could be possible that a subwoofer, placed in one 
> corner of the room, could result in better low frequency performance.
>
> Just my 2 cents :)
>
> Christian
>

<p>--- >8 ----
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