Brickwall Limiter

[firubbi]

i got this info from sos... http://www.soundonsound.com/sos/apr05/a ... /tcmd3.htm

Brickwall Limiter is rather special. Conventional limiters simply look at the digital data to detect clipping, but even where digital data doesn't reach full scale, it's still possible for the analogue signal reconstructed from that digital data to exceed 0dB. The reason for this is that digital samples are simply points on a graph, and it's possible that two data points either side of a short peak, for example, can represent a peak that exceeds 0dB. While the data may look OK, you might still hear clipping distortion when the data is replayed via consumer CD players, data-reduction codecs and so on. Apparently as little as +0.5 dBFS overshoot can cause audible problems in some consumer equipment, and this can be exaggerated by MP3 conversion and other coding processes.

Brickwall Limiter's algorithm oversamples the waveform at five times its output rate, and thus can detect if any 0dBFS+ peaks are present in a signal and apply the appropriate amount of gain reduction to prevent clipping distortion from being generated in subsequent playback systems. Unlike normal limiter meters that stop at 0dBFS, the one included here goes right up to +3dBFS to register those inter-sample peaks. Upsampling can be switched off to make the limiter behave more conventionally, but I can't see why you'd want to do this other than to save on processing power.

This particular limiter algorithms adapts the attack and release time constants to the incoming audio so as to minimise distortion while retaining the ability to react extremely quickly when peak levels are detected. If the Auto Release is turned off a manual release time can be set, but again, I don't know in what type of situation this would be an improvement. A very important benefit of this algorithm is that when limiting is not taking place, the input and output are identical, bit for bit, so the benefits of prior dithering are not lost. A green indicator next to the Threshold control lights up to show that the signal is being passed 'transparently'.

There's also a secondary mode that allows gain changes but maintains 'bit pattern transparency' by shifting the entire signal up or down by one or two bits (which equates to 6dB up and 6 or 12 dB down). Both limiter channels can operated independently or they can be linked, and according to the manual, linking to avoid audible image shifts is necessary only for very heavy limiting.

** so is can we have this option to our new Optimaster for xite-1 or
is the third party developers are thinking to program smiler plug? or
Not for next 1 year.
thanks

[astroman]

yeah, that's the proper way of doing
first you sell them the final IdiotMaximer and then you write something to 'emulate' the erroneous processing to correct it ... LOL
if you mix and master a tiny bit more on the 'traditional' end of the scale, the 'problem' doesn't even exist

there are not so few releases with such 'overshoots' though, and I'm really glad I read about it, as now I can be sure it's not in my CD player or the disk

cheers, Tom

[chriskorff]

there are not so few releases with such 'overshoots' though

Hi Astro,

Did you mean there are "now so few releases..."? Because there are effing loads of em! (Metallica's new album, Californication, RATM's Battle Of Los Angeles, to name a few... Of course, none of them can go *over* 0dBFS, but they ALL have consecutive 0dBFS samples, which means they were cplipped at some point).

The thing is, TC aren't correcting for erroneous processing, they're (1) allowing for the inadequacies of budget D-A converters, the analogue stages of which don't have the headroom to deal with 0dBFS samples, and (2) they (rightly, IMO) assume that the chances of an A-D converter recording a 0dBFS signal at any one of its sample points, and the actual analogue signal level not exceeding that level *in between* the sample points, is so miniscule as to warrant treating it as an over.

(To be honest though, probably its biggest selling point is that you can get the little red light to come on at -0.5dBFS, which will keep the client happy while still allowing for the above variables).

Cheers,

Chris

PS That bit of extra headroom will also make for better MP3 conversions of the PCM file - it's very common for straight MP3 conversions to clip when the source does not, because of the aggressive filtering involved.

PPS Of course, you could just set the maximum signal in your limiter of choice to -0.5dBFS and achieve much the same thing... unless the client complains that the red light didn't flash!

[garyb]

some of those new releases are just 50 minutes of square waves...

[astroman]

Did you mean there are "now so few releases..."? Because there are effing loads of em! (Metallica's new album, Californication, RATM's Battle Of Los Angeles, to name a few...

well, I don't buy enough to be really able to tell ...
but I remember a refund for Californication, as I could convince the guy from the shop that it's a production error...
Anyway, the ones you mention are kind of loud to meet expectations - this wouldn't bother me too much.
I find those isolated sharp clicks much more annoying that appear in moderately loud passages.
You probably know that given the right sources even something like -2dB can overshoot.
Scientific details by Mr. Katz (?) ... at least that's what my memory seems to suggest...

The thing is, TC aren't correcting for erroneous processing, they're (1) allowing for the inadequacies of budget D-A converters, ...

I hopefully don't mess TC's gear, but the 'Finalizer' was a major step in enabling every idiot to deliver a 'hot' mix - without the box it would have ended in disaster, most likely... in most cases

people usually avoided such levels and hence the phenomenon was observed only rarely, the reason for it's existance is known in signal processing, nevertheless...
So a 'proper' Finalizer would anticipate the problem...
ok, that's kind of kidding, isn't it ?

cheers, Tom

[garyb]

yes, this is stupifaction. instead of learning how to use tools, people want tools that mimic people who know how to use tools. learning how the gear works is a better way to get good results...(i'm NOT saying that the product(s) mentioned are bad or not worth using!) loudness does NOT make a well mastered production. it's just one element...

[firubbi]

very true. but in my case, i mainly do commercials for radio. most of the time the given budget is poor, i cant effort professional voice artiest and those new artiest dont have that crunch in their voice and the problem part is with level.. its horrible + ad company dont give us more than 8 hours to do the job.
im doing my best with optimaster+BX+Kompressor+soft clip. but i'll be glad if xite has this option.. it it too difficult to do?

[Tau]

SpaceF's LimFat has brickwall limiting

[firubbi]

SpaceF's LimFat has brickwall limiting

sure?... cool

[garyb]

besides, knowing how to use your stuff doesn't take extra time!

the dbx 166 has a brickwall limiter. they used to call it "peakstop"...

[astroman]

very true. but in my case, i mainly do commercials for radio. ...

the 'problem' is related to converters of consumer playback devices in the first place, not to studio or broadcast gear.
here's the respective thread from 2005, Dan Lavry explains it near the bottom of the page

cheers, Tom

[spacef]

very true. but in my case, i mainly do commercials for radio. ...

the 'problem' is related to converters of consumer playback devices in the first place, not to studio or broadcast gear.
here's the respective thread from 2005, Dan Lavry explains it near the bottom of the page

cheers, Tom

It is true but also, the need for commercial radios to develop their own sound is not to be understated. I don't know in various countries, but France used a have very lively radio networks, and on the FM, a lot of competition, and everyone wants to sound better than its competitor. Doing mastering for radio broadcast requires to be be able to conform their own sounds, which incolves eqs and compressors. For example, on a radio, they will allow a certain maximum of "débattement" (difference between high and low levels) of 1 to 1.8 dB. Others will hve even more "compressive requisites", and the material brought to them has to conform this. having the loudest possible sound with the most squary waves is a guarantee that a material can be professionally brodcasted anywhere... not meeting this standard may take a good track out of air, and it can be never broadcasted. I have a friend whos job is to check these levels and dB on every material they receive, and make sure they will output as they should through the radio processors. otherwise, it goes to dustbin, thanks and goodbye.. sad but true...
I had tracks broadcasted in the past, as part of non professional events, and hearing them through their processing was scary, I even called them to complain about the sound that resulted, and they were sorry for this, but since then (i was quite young in that time) i understood it was "my fault'" that it was not compressed as it should.. no wonder, it was direct from EPS 16+ on 4 track tapes.... I sometimes regret how naive and direct making music could be in the past, now the standard is higher, which is good in general (except those record which sound distorded on CD, DVD and mp3, as it is fashion, like Depeche mode and Timbaland were example of this trends in 2007/2008)... distrded music making major worldwide hits it's probably not the first or last bad thing that will happen (and actually, these records sound good on dance halls at very high volume... often better than the rest...)....
The last gigs I went were small, and there was no PA, just direct sounds from the unmiked drums, guitar and bass amps straight in your face, and a PA for the singers only.... the best it can be, no intermediary, but can be made only in small venues where sound doesn't need to be pushed up to be heard... but we wish them a successful career and plenty of attendance in their gigs... so i know this ambience is not for the top charts....