Jerry, can confirm lopsided 2 track result in SoundForge9, and Properties shows only 'Stereo'.
.... but when I open your MTS file in SoundForgePro10 I get 6 nice tracks, & no sign at all of the 2 track version; furthermore 'Properties' shows 'Audio Channels = 6 (5.1 Surround)'.
Weird!

Anyway,as I said originally, use the 6track version in Vegas, and mixdown to stereo if you just want stereo; given the other problem has been there for 3 years I guess it won't be fixed in VP11; anyway it's useless to you right now.

Thanks for the Oktoberfest explanations - those Germans are a mad lot.....

Agreed... this isn't just a preview bug. When it has happened to me in DVDa it DOES come out in the final render. What you see on the time line is an actual representation of the downmix as Vegas sees it.

"How would one check for this?"

Here is illustration of the role the 90 deg. Phase Shift setting plays in reproducing the problem. I just rendered Jerry's original 5.1 audio to 5.1 AC3 Pro in Vegas, once with the 90 deg. option turned "on" and once with it "off." Then muxed to TS to be able to bring all three audios back into a stereo project:



Also wanted to back off the bit of misunderstanding I created. DVDA only has a stereo timeline for preview, so when one brings in 5.1 audio (phase shift "off") it looks wrong but prepares right in a 5.1 project. Apparently when stereo is rendered from 5.1 (without the phase shift) from a stereo timeline, the levels are wrong, as is the waveform, and thanks to those who took the time to test this.

The two workarounds mentioned in this thread, starting in a 5.1 project, are to mute all but the front channels, or use the Downmix button on the Master which retains some mix control for the ambient channels and stereo width. Either of these should work, but bear further testing to be sure.

Also, before someone asks why their encoded AC3 audio is quieter than it sounds on the timeline, some suggested AC3 Pro settings are made in this thread:
http://www.sonycreativesoftware.com/forums/ShowMessage.asp?ForumID=22&MessageID=655195

Good analysis, musicvid. Educate me on the "downmix" button. I went to the Vegas Manual and it essentially says it downmixes 5.1 to stereo.

So... in a Vegas 5.1 audio project, if I preview the timeline and hit the "downmix" button, I can definately hear the difference. However, if I render out the audio to a stereo sound file, the only difference I see (or rather hear) is that the render with "Downmix" selected has slightly reduced volume. Neither render has the right-channel bias.


So, my question is... what purpose does the "downmix" button serve? Is it only for 2 channel preview?

...Jerry

For a 5.1 project: there are some fundamental and important differences between the two methods.....

- Render As Stereo (Without Downmix selected) = just the L & R mixer outputs are considered and new file made at Unity Gain.
i.e. the Stereo file is an exact copy of the L & R outputs of the mixer; the other outputs are ignored.

- Render As Stereo (With Downmix selected = L, R, C, Ls & Rs mixer outputs are considered (LFE is discarded), each with reduced gain as follows:
L -> minus 7.7dB mixed to L only
R -> minus 7.7dB mixed to R only
C -> minus 10.7dB mixed to both L & R
Ls -> minus 10.7dB mixed to L only
Rs -> minus 10.7dB mixed to R only
The gain reduction to all channels in this case ensures no overload of Stereo result when all 5.1 channels are heavily modulated.

I was just going to say the Center and Rear channels are mixed in at -3dB less than the front channels, same way a player would downmix. Except Christo's explanation is better because it gives the actual levels for each. The explanation is the same -- that it compensates for the additive gain of combining the 5 channels to 2.

So where is this 90 degree phase shift on/off button? I am blind as usual.

"- Render As Stereo (With Downmix selected = L, R, C, Ls & Rs mixer outputs are considered (LFE is discarded), each with reduced gain as follows:
L -> minus 7.7dB mixed to L only
R -> minus 7.7dB mixed to R only
C -> minus 10.7dB mixed to both L & R
Ls -> minus 10.7dB mixed to L only
Rs -> minus 10.7dB mixed to R only"

In my tests I reported above, both Ls and Rs were subtracted from the L channel and added to the R channel. If +90 deg phase shift had been applied to the rear channels first, then the L channel would have -90 degree rear added and the R channel +90 degree rear added. It is now symmetrical. However, I don't see why both rear channels were applied to both L and R, though. Adding just Ls to L and Rs to R would have made more sense to me as in the quote above. (Ignoring scaling to prevent overload, for the moment.)

Peter we are talking at cross-purposes I think - I am speaking about 5.1 original tracks Render As a Stereo WAV file, which can subsequently opened in Vegas (Jerry's "render to a new track"), and is very simple - I suspect you are speaking/worrying about a Stereo AC-3 file, which cannot be utilized by Vegas, and is a very complex encoder process, which may have some bug in the Vegas Encoder related to phase..... Perhaps I should have been more explicit....

You said: "I loaded them all into a 5.1 project and listened to them with stereo headphones. The left, centre and left rear appeared in the left headphone, while the right, LFE and right rear appeared in the right phone."
upon re-reading your 'test' above, I think the way Vegas outputs are setup for your headphones MONITORING is what you observed and is adding to the confusion; just that and nothing else... it's the stereo pairing of the outputs...I think you will find it's the way the 6 track outputs are resolved to 2 track in Preferences | Audio Device setup.
e.g.



is how I setup my soundcard, which happens to have 128 Inputs & 128 Outputs....
but for a STEREO or 2 channel I/O soundcard card the C,LFE and Ls,Rs are just sent to the SAME L,R channels as the Front; very likely something like:

I (and I thought Jerry as well) was talking about what happens when a video with 5.1 audio is dropped into the timeline of a stereo project. The resulting mix was deduced by looking at the audio waveforms in an audio editor. My red herring was to mention what I heard in the headphones, which has its own peculiarities.

Red Herring:



Correct, so we suggested the "stereo" approach has fairly obvious problems, and some speculated as to why .... therefore best approach if Jerry wanted to continue working in just stereo was to use the 5.1 tracks and Render (with possible Downmix) to stereo..... it was Jerry who observed and raised the question regarding difference between Downmixed and NonDownmixed Stereo Render levels....

Don't wait for me. I'll catch up after I've had my herring for breakfast.

"So where is this 90 degree phase shift on/off button? I am blind as usual."
In Vegas, it's on the Preprocessing tab of the AC3 Pro 5.1 custom settings.

Here is a summation as I understand it:

* Vegas and DVDA Stereo timelines only respond properly to 5.1 source that has the 90 deg shift flag ENABLED.

* The Panasonic footage is among those that do not have the 90 deg flag enabled.

* Currently, the way to get a balanced stereo mix at render from this footage is to open it in a 5.1 project. Rendering this from inside a Stereo project will not work in current versions of Vegas.

* From the 5.1 project, one can use their own mix or mute preferences to render a balanced stereo file, either with or without the use of the Downmix Master button, but with different results; the Downmix option compensates for both the additive effects of mixing and relative temporal channel levels.

* Since Sony has acknowledged this bug three years ago, maybe it is fixed in Vegas Pro 11. If not, considering that so many cameras now natively shoot with 5.1 audio, now might be a good time to revisit the issue.

Good summary, musicvid. I think my SOP will be to open my footage in a 5.1 project, select the downmix option and render as 2 channel stereo.

"The Panasonic footage is among those that do not have the 90 deg flag enabled."

It appears that at least three Sony cameras also exhibit this. Unknown Sony cameras from PeterDuke & dalemccl and an HDR-SR1 from john_dennis. Are there any cameras that record 5.1 audio and do not exhibit this problem?

...Jerry

For the record, my camera that has 5.1 capable audio is a Sony HDR-XR520VE.