surround volume

[AmericanDiamond]

I hope that this is the correct form to post this in.

Does anyone know where I can find a VST effect/plugin that can increase the volume of the surround channel (I'm not sure if it's called the surround channel or the rear channel)?

I know of the 'surround encode', 'surround echo' and the 'surround panning' effects, but whenever I put sound on the surround channel, it tends to be lower in volume on the mp3 than I want it to be and not at the volume level that I set it in MPT.

So, I would like a VST effect that can allow me to take the surround channel on the completed WAV file and modify the volume/gain to what I desire it to be, like maybe some type of surround remixing tool.

NOTE:  This is for the ordinary stereo 2.1 surround, NOT 5.1 or 7.1 surround.

Thanks.

[LPChip]

Note that when you export to wav or mp3, all surround information is lost, as a stereo file can't have any form of surround. (Someone, correct me if I'm wrong, but as far as I know, only AC3 supports surround)

Playback of surround, therefor, will only happen inside OpenMPT.

If your endgoal is to have it being played as mp3, then I strongly suggest to abandon the surround option.

[Sam_Zen]

Weird. I read this post in the 'Open-source and free software', and thought indeed "not the proper form for this".
I wanted to reply, and in the meantime the post was moved as a proper thread here. Nice.

This is an area with many confusions. In terminology and technology.
So what does "stereo 2.1" means ? I haven't got a clue.

I'm not sure if it's called the surround channel or the rear channel

Channels that is. These terms are both by consumers used for the same horizontal speaker positions.
But that's not so relevant. It's about handling more than 2 channels of a soundfile.

LPChip is right, exporting to MP3 will loose the surround options.
A workaround could be to save the groups of channels with or without the surround enabled seperately into WAVs.
Then mix them into an OGG file, which can contain multi-channels.

[LPChip]

Actually 2.1 is just stereo. The 2.1 is referred to a speaker setup with a front left, front right and subwoofer.

[psishock]

this might be interesting for you:
http://en.wikipedia.org/wiki/MP3_Surround

[AmericanDiamond]

Thanks to everyone that answered.

From what was said, I think I meant the rear channel, because, for instance, if I dedicate a channel in OMPT to surround (using the "S91" option) in a song and then export it to a WAV file, if I play the file and/or convert it to an MP3 file, I can still hear it "sort of" the way it was intended (that's why I think I meant to say the "rear channel" or maybe even the center channel).

I posted because the rear or center would be at a lower volume than expected only when I converted it to an MP3 file.  So, I think I understand what LP and you others said about the surround information being lost, and since you all said that, I'm thinking I was really talking about the rear or the center channel, since I can still hear that.

As you can probably see, I'm a bit confused with the difference between rear/center channel and surround.

Thanks for the link.

[Sam_Zen]

The 2.1 is referred to a speaker setup with a front left, front right and subwoofer.

Well, (you know my attitude about this), I was already afraid of that (imo silly) construction.

To attempt to decrease the confusion about this, it's important to realize first the difference between a stereo-source,
which is decoded by some circuit into more outputs in some way, or having discrete tracks, directly available to play back at the same time.

If decoding is concerned, the center channel is created by ignoring the differences between left and right channel, so only the common sounds.
Logically this result is decreased in volume, because a straight 50 % of both sides would be too loud. The mix is not lineair.
Of course this center-trick can emphasize some sounds. Quite logical, because most of the time talking heads or singers are produced in the center.

The same thing is valid for the center subwoofer. Most of the time a bass or a kick sound are produced in the center.
Plus the industry had the argument that one couldn't hear any panning difference of low frequencies anyway. Which I deny.

The downside of having a third speaker in the center of a stereo panorama will be an audible 'narrowing' of the experienced width.

Creating rear/surround channels is another aspect. If artificially decoded, most of the time it's some algorithm (S91) using phase shifts of the source.

Returning to the basic topic question here : why has the channel dropped in volume ?
Because phase shifts of the same original are involved here, it's not unthinkable that in the mixed result some things get weaker.
If you mix two versions, but one with a 180 degrees turn, the result will be silence.

[Snu]

i dont know much about this either (i stick to just stereo), but i think before this gets too complicated we should make sure to differentiate between dolby pro logic surround (which is 4 channels encoded into 2) and plain surround (which could be 4 channels, 5, 7, whatever).

i have a couple questions:
are you exporting mp3s directly from modplug?
how does an exported wav file sound? is the volume wrong on that?
what player are you using to listen to the mp3? have you tried a different player?
what is your soundcard and speaker setup?
what windows sound devices are modplug, and your mp3 player using? its possible the back channel settings are different for the wave mapper and direct sound devices.

my first guess is the mp3 decoder you are using doesnt properly support dolby pro logic... it could be a variety of issues tho.

for the vst thing... your only option would be to try and find a vst dolby surround encoder, and set modplug to quad channel mode instead of stereo (this turns off modplug's dolby encoding). i dont know of any vst that does this tho.

[AmericanDiamond]

Because of quality issues, I never encode to MP3 directly from Modplug; I only encode to WAV (I used to encode in 16-bit stereo but recently I began using 32-bit, both varying between 200% and 400% stereo separation) and then use a third-party MP3 encoder.

When I create the WAV file, there are absolutely no differences heard; everything is encoded as it's supposed to be, with the correct volume levels for the rear channels.  It's when I encode from WAV to MP3 that I lose the rear volume.

I asked myself the same question of whether it's the player, but I don't think it is; I use Winamp 5.3, but I can put the MP3s on a portable player or use RealPlayer (a sort of testing backup) and notice the same loss.

As far as my speakers and soundcard, I have what I call the "sufficient" Conexant sound card and the two monitor-detachable speakers that came with the HP Pavilion 6573Z (yes, old, but they still work).  The only way I can correct the rear volume issue is to redo the songs all over again with a higher volume setting for all notes/channels set to S91.  I tried that in the past, but it gets VERY time-consuming, not to mention tedious.

I have scoured my PC to look for any setting that may be causing this difference, but I haven't found anything that will allow me to modify any back channel settings.  By the way, in Winamp 5.3 I use a DSP called Surround Channel Mixer v. 0.1 that allows me to change the ratio of the surround channel with a range of 0% to 150% only during playback, but, alas, it's a DSP and not a VST.

And yes, I was talking about Dolby Pro-Logic Surround.  I didn't know the difference before.

Also, if there is a VST effect that could mix the front and rear channels independently, I would appreciate it if someone could advertise one to me, which would be a big help.  Could I translate the WAV or MP3 file to 5.1 and do that with some VST effect?

[bvanoudtshoorn]

Perhaps try encoding to a format other than MP3, such as OGG, FLAC, or even WMA. I think it's an artifact of the MP3 compression.

[LPChip]

Its indeed the encoder that makes this change. Perhaps the encoder has an option for surround, or there's a different encoder out there.

Alternativelly, you could try removing the surround settings and save it as wave to see if that compensates for the mp3 problem.

[älskling]

I don't quite understand why you use surround effects with only stereo speakers in the first place. It's not meant as a stereo effect and it will cause unpredictable results.

Anyway, what MP3 encoder and settings are you using?

[Sam_Zen]

I don't quite understand why you use surround effects with only stereo speakers in the first place.

Fully agree.
But the results aren't that unpredictable.
This simple surround mode copies the data from one channel to the other but with a reversed, so 180 degrees, phase.
This results in the sense of a 'wider' panorama, because some common sounds in the center are gone.

The advise by [BvO] is correct. Use other formats, which can contain multiple soundchannels.
But in the end, you'll still need the appropriate number of speakers to reproduce it.

I once made a test file with 9xy codes, to hear the result :
http://www.samshuijzen.nl/sam/plainmods/codetst2y.xm

[AmericanDiamond]

I'm not sure if we're on the same page when we're talking about surround.  I've already made songs that are "surrround" capable, and the rear channels can be brought out with the Surround Channel Mixer DSP I mentioned in the previous post, meaning that the encoding IS there.  It's just that the volume isn't where I want it to be.

When I use PaceMaker in Winamp and select the voice removal option, those "S91" channels/notes are singled out, and whatever channel those are on, THAT'S what I wanted to make louder and/or manipulate in either WAV format or in the finished MP3 format.  I hope that illustrated more of what I was talking about earlier; sorry for any confusion on my part.

The other formats like AC3 and OGG sound great, but at this point I'm not sure if I would like to deal with switching between file formats.  However, if it can convert losslessly to WMA so I could squeeze it into my Nomad MuVo (the original; yes, I still use that and don't have an iPod yet), I'm on board.  I'm trying out LAME encoder to see if that makes a difference for the time being.

I would try saving the S91 channels as a separate WAV file, but that would go back to the OGG vs. MP3 thing.

O yeah, I use the freeware "WAV to MP3 Encoder 2.5" by Mthree Development to encode in 128 kbps Stereo.  I've tried 160 and 192 kbps, but there was no change.  So I'm definitely going to try LAME.

[Sam_Zen]

Yep, LAME is the one, if you want to deal with MP3.
Some related tools :
Lame FE by Jacek Pazera (open source)
Lamedrop by John Edwards. WAV <--> MP3. Just drop file on object for conversion. (R-click for settings).
The same construction for another 'dropper' : Oggdrop regarding WAV <--> OGG.
A versatile multi-format converter is Winlame by Michael Fink.
A list of compatible formats can be read here.

I would try saving the S91 channels as a separate WAV file, but that would go back to the OGG vs. MP3 thing.

I don't understand the OGG vs. MP3 thing here.
If you save a seperate WAV with the S91 channels, then I guess it's just a matter of increasing the volume, save it again.
And integrate it back in the target-file.

If talking about lossless, both MP3 and OGG aren't the ones to use (although OGG developments go in that direction).
Then you'll need the formats FLAC, WV or APE. Of FLAC I know it's multichannel.

My advice about hesitating switching file formats : just start implying it, wherever it can.
(an aspect when publishing tracks : the MP3 format has copyright, the OGG format is open source)
The next version of FireFox will have the OGG format fully integrated in the browser, so no plugin needed.