Surround Panning of existing 5.1 tracks

Angels wrote on 11/27/2010, 5:09 PM
I've got 5.1 multichannel wav files mixed in another DAW that I import into Vegas to sync to video and burn to blu-ray for testing. When I import the 5.1 it appears as 6 different tracks so I'm trying to figure out the best way of assigning the panner.

Turning on only the correct speaker for each of the 5.0 tracks is obvious as is assigning the LFE track to the LFE. But what's the best way of assigning the panners to insure that each channel is playing at 100% of its intended volume?

L,.R.Ls and Rs can all be panned so their levels are at 0dB, but Center can't be set at anything but -6dB no matter the pan law. So I put the orange carat in it's default position (centered) and just assign the speaker. Is that the correct way to do it? Thanks.


ChristoC wrote on 11/27/2010, 6:34 PM
Right-click on each panner, and set Pan Type to "FILM" (except LFE of course!); then double-click each panner to get big pan window and move carat to the intended speaker exactly; now all channel tracks will play at unity gain to correct output (although the panner says '-6' trust me the gain is unity).
musicvid10 wrote on 11/27/2010, 7:21 PM
When 5.1 audio is imported into Vegas as discrete 6 channel PCM, the tracks and positioning are in exact proportion to the original mix; IOW, if the original pan had the rear track 12% to the front and 88% to the rear, there will be 12% of the rear audio in the Vegas front track, even though it is visually panned 100% front on the timeline.

This is the long way of saying you may want to leave it exactly the way it imported; as it is the same as it was originally mixed.
ChristoC wrote on 11/27/2010, 9:33 PM
When 5.1 audio is imported into Vegas as discrete 6 channel PCM, the tracks and positioning are in exact proportion to the original mix; IOW, if the original pan had the rear track 12% to the front and 88% to the rear, there will be 12% of the rear audio in the Vegas front track, even though it is visually panned 100% front on the timeline.

Musicvid, you may want to revisit what you just said; here, that simply just does not happen..... user must select correct panner and manually pan each channel.
musicvid10 wrote on 11/27/2010, 10:33 PM

"user must select correct panner and manually pan each channel."
That would only happen if the WAV channel routing is unflagged.
It doesn't sound at all like the OP is having that problem.

Since you are an experienced audio guy, there must be a better way to say what I said, however I just verified my findings with a test.

1) Took existing surround project, rear channel audio was already panned -6dB rear, -15dB front.
2) Took a 20 second 1KHz tone, layed it on top of the rear track.
3) Rendered out 1 minute of audio including tone segment, to 6 channel discrete PCM at 16/48 (same as project).
4) Pulled newly rendered WAV into a new 5.1 Project and soloed front track. Panner is 100% front by default (the rear panner is 100% rear by default).
5) At the point where the test tone begins, it is clearly audible in the soloed front channel, ducked under the original front audio as I expected, and continues for 20 seconds and then reverts to my original mix. The same is true for the Center channel.

So, if I want an imported six channel discrete WAV file to sound exactly the same way the 5.1 was originally mixed and panned, I don't touch the surround panners at all. The previously mixed front channel has become the new front channel, panned dead front.

Likewise, to retain the original mix volume in the Center channel, I don't believe one would change the balance type from its default. This could be easily tested, and I will do that time permitting.

If you can distill that information better than I, in a manner that will be easier for the OP to understand, I will feel indebted. Since I think my original statement was misunderstood by you also, I hope you will be willing take another shot at it.

ChristoC wrote on 11/28/2010, 1:02 AM
OP said multichannel wav files mixed in another DAW

As far as I'm concerned, an imported multichannel WAV file should be panned/routed 100% to each designated direction.

... so I did the same
- Vegas correctly creates 6 tracks, aptly named "Channel 1 ..... 6", but 5.1 panner for each track is set centre, LFE is not set (Channel4)
- depending on your 'default' 5.1 panner type, all but FILM result in bleed to other channels even when panned hard to one speaker
- that's why I gave my original recipe, because if you follow that then you can't go wrong!

Angels wrote on 11/28/2010, 4:56 AM
Guys, I figured it out:

1. I created a 6 channel file in SoundForge.
2. I put a 10 second -20dB 1 kHz tone on channel one, and then incremented each subsequent channel by 100 Hz to check for inter channel bleeding.
3. I played this tone from SoundForge on my RME Multiface via ASIO and used RME's Digicheck to monitor the output level. All tracks read -20 dB in Digicheck.
4. I then imported this track to Vegas, which created 6 audio tracks.
5. I then left the surround panner at it's default center-field position, assigned track 4 to the LFE, and only turned on the speaker corresponding to that track's assignment: L,R,C,Ls,Rs.

With Pan Types: Add Channels (0dB Center) and Balance (0dB Center) my output levels were all exactly what they should be, based on the reading of the Digicheck meters. There also is no inter channel bleed. If on top of the single speaker assignment I pan to that speaker, L,R,Ls and Rs now will be +6dB too loud. So my original methodology seems correct.

With Pan Types Balance -3dB and -6dB, the Front and Rears will now be -6 and -12 dB down respectively. Panning to each speaker in this case will bring each channel to their nominal output. No bleed and no change in the center or LFE channels

With Pan Type Constant Power, the Fronts will disappear altogether(?), and the Rears will be -6dB down, nominal if panned to their speakers. I'm not sure what's happening here with the fronts (bug?).

And finally with Pan Type Film, Front and Rears will be -7dB down if the panner is centered in the sound field. Panning to their respective speaker returns the levels to nominal.

Now we all know, QED :)
musicvid10 wrote on 11/28/2010, 8:17 AM
Glad you got it figured out, and great methodology.
ChristoC wrote on 11/28/2010, 1:52 PM
Now isn't that interesting....

For first time in my life, I used SoundForge to generate 5.1 file as above...

First observation is that we are dealing with 2 distinct behaviours - when that SF file was dragged into VP, just 4 tracks are created =
Channels 1/2 = L+R Front (stereo),
Channel 3 = C,
Channel 4 = LFE,
Channels 5/6 = Ls+Rs (stereo),
and unused speakers are turned OFF in all the panners.
when I add 6-Chan WAV files created in other DAWs (e.g. ProTools, Pyramix & Soundscape), VP creates 6 mono tracks, one for each Channel.
These tracks are all given panners set to centre-of-room, including LFE channel 4, all speakers ON.......
Conclusion: VP behaves wildly different depending on source of valid Multichannel WAV, which is rather disconcerting.

Second observation is that the VP handling of the above SF 5.1 file does indeed pan & play correctly with one important caveat - I have my VP setup to default to FILM panner - with Film panner active the levels are not correct e.g. the L+R Front stereo pair is correctly Panned Centre Front on the Panner, but by nature of the Film Panner there is no resultant L+R Front sound , and the Rear Ls+Rs stereo pair levels are incorrect (3dB low)!
Conclusion: User must change panners back to 'Add Channels' to get correct result, or never use Film as Default Panner.

Therefore the answer to OP is not so easy!!!!
- Behaviour of VP changes depending on file source.
- Behaviour of VP changes with selected 5.1 panner.

Life is not meant to be easy!

Angels wrote on 11/29/2010, 7:59 AM
How VP imports a multichannel wave is due to presence or absence of Metadata in the file and what it defines. Usually I export with Metadata on, but recently I it caused problems in this current project so I took to omit it for this one. Without Metadata defining to VP what the channels are, it will just import each track as a simple mono file, no panning assigned, all speakers on.

In Vegas 9 (I haven't moved to 10 yet), the Film setting sets the rears at -7 dB down by default (again according to my Digicheck meters), which isn't in spec at all. They should be lower by -3dB because that's what the Dolby spec specifies for setting the Rears in theatrical productions.

But what's inherently wrong with doing it this way is that in principle the track panner shouldn't do this: it's supposed to be handled by the monitoring. If you calibrate your speaker levels to Dolby spec for Film work, your Rears will be -3dB down from the Fronts, so if you play back 5.1 tracks panned with the default Film setting, you'll be lowering the rears again and you'll definitely be out of spec. The right way to implement monitoring standards in a DAW is to have an output monitoring section with it's own presets that's NOT part of the rendering chain. That way you could adapt your monitoring to the media and render your output to spec. Alternatively, you need a monitor controller to set your speakers to the different monitoring standards as required.

I think Sony Media should give the Vegas surround panner a review, just to get all the specs in line with professional standards and industry best practices. They should expand the literature to include explanations and support documentation for the choices they make. There's tons of docs over on the Dolby site worth pouring over... you're right ChristoC: it's NOT a simple topic!
ChristoC wrote on 11/29/2010, 3:01 PM
I agree it should be reviewed; I don't use Vegas as my primary DAW, but it's useful for spill-over, but clunky because of these weird behaviours, and the need to check callibration with tones everytime I setup a new project.
ChristoC wrote on 11/30/2010, 2:34 PM
Angels wrote In Vegas 9 (I haven't moved to 10 yet), the Film setting sets the rears at -7 dB down by default (again according to my Digicheck meters), which isn't in spec at all. They should be lower by -3dB because that's what the Dolby spec specifies for setting the Rears in theatrical productions.

I am mystified.... here if I make a new session, add a mono tone track, and play thru 5.1 FILM panner, I see exactly correct & expected behaviour.
i.e. moving pan around the 5 speakers, the tone outputs exact same level in all directions.
This measures correct on all external soundcards & meters etc.

How did you determine the -7dB drop in Rear? Are your Mixer Master faders all set to '0'?

Angels wrote on 12/1/2010, 2:32 PM
My observations were based on turning only one speaker on per channel (as per function: L/C/R/Ls/Rs respectively), not on the behavior of the panner itself.

But in Film mode I was in fact wrong: it's actually -7 dB for BOTH fronts and rears. As you've mentioned before you have to pan to the speakers in Film mode if you want unity gain, whereas with the "0 dB Center" modes, all you need to do is assign the speakers; if you pan them towards the speaker in these modes you won't get any gain at all from center to their assigned speaker, but you will get loss if you go farther than center away from the assigned speaker.

It would seem that the dB indication for the different modes shows how much gain is subtracted from unity at the center position.

The levels are plain to see on both the VP meters and my sound card's. I suggest you run your own tests so that it's all 100% clear; it doesn't take long.

ChristoC wrote on 12/1/2010, 6:37 PM
Yes .... we are both right! -- and yes thanks, it's all perfectly clear to me.... but there's a difference to our methods which is why we seemingly get different results; here's why:

My test, and first response to this Topic, was done with 0dBfs tone & moving the carat to each speaker, which gives UNITY GAIN.

Your test was done with 0dBfs tone & leaving the panner carat static in the centre, and switching speakers on and off so you get signal -7 to a speaker.

- obviously if you move your carat towards speaker you will get unity gain!

Either method is perfectly correct as the FILM panner is an Equal Power panner which means it adds gain when panning towards the speaker.
Angels wrote on 12/1/2010, 9:54 PM
You know, maybe there should be a way to import a 5.1 track to a single 5.1 track with no panner at all, a default "straight" setting, assigning all channels at unity to their respective outputs instead of dividing them up into 4 or 6 tracks (depending on the presence of absence of metadata).

It would make it a lot simpler to mix multiple surround streams. And for a video app like VP, that could be a very powerful asset and it sure would make it simpler to mix multiple surround streams.

Just thinking out loud... ;-)
ChristoC wrote on 12/1/2010, 10:44 PM
The voices in your head may not be real, but they have some good ideas!

Angels wrote on 12/2/2010, 5:57 AM
Funny: they keep telling me that they are.... ;0)
rraud wrote on 12/2/2010, 7:19 AM
I have not tried it, but can't a previously finished /encoded 5:1 mix be dropped directly into DVD Arc.

The voices in my head say, "Pro-tools, Pro-tools, Pro-tools." I am seeking psychological help for this affliction.
Angels wrote on 12/4/2010, 12:28 AM
We're talking about mixed or source 5.1 tracks, not encoded tracks, into VP, not DVD-A. Yes I think your right about DVD-A.

As to the voices... best to listen to them when they're right. The trick is knowing when they are... ;0)
ChristoC wrote on 12/8/2010, 8:51 PM
I've now found out the reason for the 2 distinct behaviours I outlined somewhere above.

There are two varieties of multichannel WAV formats: WAVEFORMATEXTENSABLE & WAVEFORMAT.

It appears SoundForge writes the WAVEFORMATEXTENSABLE when asked to Save As a "5.1" format, but WAVEFORMAT when using Save As "Default" multichannel.

I have also discovered that some major brand DAWs reject files when they are WAVEFORMATEXTENSABLE type; i.e. it is not universally supported.