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i was reading that when you put the original stereo in the FL and FR for 5.1/5.0, the Center is useless and don't do differences if is used or not as you have the 'Center image' from FL and FR.

(i don't agree as the SL have part of FL, SR have part of FR and you'll have more 'sides' and less Center image.
this change the general balance between levels of the Center/Surrounds in the 'music'!)

creating tones in a.audition where:
Left 220Hz, Right 440Hz, Center 110Hz + 330Hz was done stereo to be used as source.
after that was 'extracteds' L, R, C ,LFE, SL & SR from this source.
using this 6 channels whit LFE at 0dB, was encoded 2 x AC3 448k where one have Center and other without Center (center channel is present at 0dB).

better is hear the samples than read words, i upload this 2 x 48k AC3 samples more the sepereteds 6 waves channels 24b/48k, 5 seconds each one.
the waves can be used as source and do your own test encoding as DTS-CD(need downsample), 5.1 waves to hear in pc or other.

the samples have only 2665 KB(.rar), please download, hear and tell yours impressions.



all samples have low levels(volume) don't will damage anything!

cheers!

I think all it takes is a quick listen to a source put through SPEC-CC to figure out that an extracted center, with the full stereo source in the fronts, is far from "useless."

The point of having a center is obvious, and that's to bring the listener's attention to the center, as well as to accentuate sounds that belong in the center in the soundfield. It's exactly what you later say with the rears, and I was just about to write just that before reading more closely...

I have (many times) put the original stereo in FL/FR, then used extractions of Center and put them in to "C" to boost/enhance vocals/snare when appropriate. It's all a matter of taste, but just like River161 said: " it's far from 'useless' "

If it sounds worse than the original, then don't do it ... if it sounds equal or better than the original, then do it! (There are a few that I've done where I chose NOT to put anything in "C", but that was because the source did not have much in "C" to start with)

Jack.

hi River161, Jack and all.

bah...after write long post was needed to login again and i lose all...

well the resume of the lost post is:
~80% or more of the basses are in the centered image of stereo source.
without Center channel we lose only the 'center image' level comparing with surrounds as all is present in the stereo source(L&R) but we lose the level of the subs to LFE as all channels are redirecteds.
without center you lose less in authoreds cds/dvds via coaxial/optical but using spam multichannels from pc to amplifier you lose more as don't have basses redirections in this last case.

no matter if the voice, guitar, trumpets or other is in only one side only, the basses are centereds in ~80% of the musics and will be redirecteds...think when the bass is in one side only and is imaged in center at the same time or when have 'mad' transitions between channels like Hendrix... when the bass is passing from one side to other, what will happen with the LFE level in the middle of the transition? the same question to voices and instrumments in transitions.

i don't know(don't remember) any music that have 'center image' empty where all instrumments and voices are in extremes only.
if exist any music only with extremes, then we can let the center channel empty and only in this case!
then...we have to use the center IMHO(it's not a 'law', just personal argumments and taste)

this is why i posted the AC3 and the seperateds waves.
to do your own seperation, create an empty stereo wave in any wave editor, copy and past the L to left, R to Right and save...you have my source to do the extraction.

cheers!

River161,

i understand the situations that you and Fantasia posted, very clevers.

have dozen musics from Beatles and others where the bass is imaged in the center, others where the bass is in only one channel...

to ilustrate a little more my 'details', think in the music "Hey Bulldog - Beatles' where the voices are in the right, drumms, guitar(piano is more in left in the left but the basses are in the center.(basses are in L & R in the stereo source but imaged in center)
when we extract channels in this music, we'll have less basses redirecteds to LFE, the basses will be redirected only from L & R.

what happen if we encode this music with LFE empty(i did here) :
voices in R + Rs. drumms, guitar(piano) in L + Ls.
we have now 'twice' of each intrumments.
the basses from L & R are redirecteds but not the bass from Center channel(that have only the bass), will not be redirected as was extracted in the center...we will have less bass. of course we can adjust LFE level.
the same will happens when the voice or other is the 'centered image', the level of the center channel more the image from left and right will decrease comparing with have in the fronts and surrounds as this channels repeat what have in each side.

then the result of the 5.1 with empty Center will be
L+Ls(2 x levels guitar and drumms), R+Rs(2 x levels voices) & C/2(1 x level bass)....(half level of center as we will hear only the image) and LFE/2 if the bass is centered image too.

off topic(not too much) :
i'm changing my mind to encode with LFE empty. doing that, is 'impossible' to get the rights redirections of the Basses like happens with this music using empty Center....then i always will you the Center.
in other side, i like to hear in pc via spam cables to receiver(6.1) but with empty LFE, few basses are redirecteds to the LFE but without Center is really impossible as i lose twice.
from medias from standalones to decoders, the basses are redirecteds from all channels, is ok...(well, my receiver is 'full range' in all channels, if i encode Ls or Rs alone with basses letting L, R & C empty, the basses are redirecteds to LFE, i don't know if all receivers do the same)

i'm trying to find the best of 2 worlds, i mean...few LFE: i'm testing encodes with LFE at -25~35dB and/or to redirecting part of the basses to Ls & Rs...no conclusions yet!

cheers!

Fan51(prof.), thank you for the hint.

I seem to change my mind every few months as to how I'd like to deal with the LFE. I used to have a more present LFE channel (-4 to -6 dbs from the fronts.) I also experimented with no LFE, as well as with a much lower LFE (-10 dbs from the fronts.) I just finished a conversion in which, instead of working off RMS levels, I maxed the peak level of the LFE on each track at -10dbs. I liked the results there. Like I said, I can't ever seem to make up my mind.

Early pseudo-stereo type recordings like the Beatles present a very different challenge. There have been times where I've rewired channels in order to center the vocal. There's been time where I've left it as is. I've used 4.1 in the past for sure, and have worked with SLICE and ArcTan as well. It's labor-intensive work, but I think that, if you're able to get that right balance between placement and soundfield, the rewards are more than worth it.

i don't know how you treat musics where have transitions between channels ...i can't imagine the right volume balance in the middle of transitions without Center channel.

Parson do good surround in 4 channels because his sources are 4 or more independents channels and can adjust the level of voice or each instrumment sepereted...lots of independents channels to mix as desired!
send me the independent channels sources and i do seamless!
he is not extracting 5.1 from stereo, this is another story....different road and 'more hard'!
maybe he can't do like we do here using stereo sources...?!? don't know.

i don't know if Alan Parsons is one of the best surround producers because i don't like of his music, i never could hear one entire album....is bored for my taste..no blood in the vains!
some of his fans confuse his possibilities to use 'aparatos' to do 'sounds' with music creation.
i only know that he learned a lot with G.Martin/Beatles in Abbey Road album as tape operator(or something) and ...nothing more.
he have one album called 'I Robot" where he 'did' one music exactly equal/seamless as have in DSOTM, who don't recognize?
i only heard one time as one friend requested 5.1 and was needed do tests and never more will repeat.

then...from extractions from stereo, we need Center or pm me with one music with transitions where in the middle of the transitions the center image don't lose level in 4.0 or 4.1, i never heard and will be very interesting know that exist!

cheers!