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Subject: no LFE signal!
Posted by: blade_runner
Date: 1/4/2005 3:24:05 AM

Hi everybody,

I got a problem...

I am using Sony Vegas 5 to create Ac3 5.1 files
When I use this file to burn a DVD, All the tracks that I had send only to the LFE channel seem to be gone
There are some of the other sounds on the LFE, but I had a track with a deep heartbeat sound that I only wanted on the LFE and on none of the other speakers. But now I can´t hear it at all!

I used the same vegas session to create a WMA and a WMV file with 5.1 sound and this works perfectly when played on a PC with a 5.1 soundcard.
There seems to be a problem with the AC3 but I have no idea how to fix it.

Anyone there who could help me?

Thank you

Subject: NO LFE
Reply by: scifly2
Date: 1/15/2005 11:05:31 PM

When rendering to ac3, have you checked the custom settings to see if the box is checked for Enable LFE ?

Subject: RE: NO LFE
Reply by: imac
Date: 7/29/2005 2:44:22 AM

So my deadline is just a few days off, and I discover LFE channels are not encoded to AC3!!

What is this!


That is the whole point of using Vegas-DVDA...

This is a music project with heavy bass content, the whole point of 5.1 is the .1

Do I have to learn and use a whole new app to get this done?

Subject: RE: NO LFE
Reply by: B_JM
Date: 8/3/2005 11:41:25 AM

LFE is encoded to AC3 with vegas, make sure you have something on the LFE track first off ..

and the whole point of 5.1 is not the ".1" , in fact it is completely optional and in many cases not really required depending on content ..


Subject: RE: NO LFE
Reply by: DJPadre
Date: 8/9/2005 4:39:17 AM

"So my deadline is just a few days off, and I discover LFE channels are not encoded to AC3!!

What is this!


That is the whole point of using Vegas-DVDA...

This is a music project with heavy bass content, the whole point of 5.1 is the .1

Do I have to learn and use a whole new app to get this done?"

Whered u get THAT info from??
Hell, i ditched 30ks worth of Hardware encoders when vegas 4 offered mixing in 5.1... its THAT good..

if your having issues hearing the heartbeat, you might want to tweak your EQ, compression (as in dynamic compression, not file compression) and LFE frequencies vs the track EQ frequencies and make sure that your running the correct mix so as not to allow it to cut itself off the LFE range.

If you think Dolby Digital is only to be used as a wow factor element, youre sadly mistaken...
thers much more to the technology that the surround sound element.. have a look at the compression algorythms as dynamic range difference of Dolby VS MPG audio VS DTS ....




Subject: RE: NO LFE
Reply by: Bob Greaves
Date: 10/7/2005 4:55:42 AM

LFE is in there - not to worry! It just can get a little ticked off, so to speak, until you tick it back on.

But - having said that. On a Music DVD, I would find it advisable to not use the LFE at all - and if at all - very little.

WHY? Because 5.1 mixing when not done right tends to sound fabulous ONLY on the system upon which it was mixed. Get that little puppy in the hands of three different bass management systems and one will sound great, in another your bass could almost entirely dissappear, and in another the bass could be all you can hear.

Subject: RE: NO LFE
Reply by: Padre
Date: 1/12/2006 5:06:20 AM

Hey Bob, this is wher enormalisations and compression come into play..

essentially, within ur project settings u shoudl have teh LFE cutoff set to a standard frequency.. usually 120hz for film (its a preset.. funny though that there is also a DTS preset but no DTS encoder...lol)
mooooooooooving on.. lol

yeah so once u have this configured, the AC3 encoder shoudl autoatically run this filter on anythign using an LFE tag, wither it be on the timeline as raw mixing material, through to the mixdown

Im yet to have a a problem with the variable sound systems ive tested on. At the moment im runnign a Sony 6.2 (yup, 2 subs) Surrond sound config in my studio and the bass is crisp clean and doesnt peak the subs whatsoever.

its all about the mix, so long as ur mix is CLEAN, then u wont have a problem, however i find running a parametric eq to minimise the low bass rumble does help for the LFE track as well as combining that with a clipped peak restoration plugin to keep levels from peaking.
LFE is exactly that, low frequency effects, not subwoofer as most ppl assume, so the LFE cahnnel itself can carrry alot more to boost the artisitic side of the work if used appropriately and not overkilled (although that can be fun ;) )

Subject: RE: NO LFE
Reply by: JeffreyPFisher
Date: 2/24/2007 1:50:24 PM

In a stereo downmix (the player), the LFE is dumped. Are you playing a 5.1 project in stereo? If so, then the normal processing ignores any LFE content whether it's checked in the meta data or not.

JPF

Subject: RE: NO LFE
Reply by: DJPadre
Date: 5/16/2007 5:47:32 AM

in addition to that, the post imix metadata within teh dolby stream will dictate the additional dynamic rang compression to "squeeze" 6 channels into 2 without washing out the mix.
Standard default (and recomendation from DD themselves) is -3 db per channel

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