TOPIC:

Hi All

I know this subject has come up before but I'm still struggling to find a solution.

We are trying to produce a 5.1 multitrack QT movie ProRes Master. The audio has come from a pro audio house in 8x mono tracks from ProTools, and we are producing our Master in the usual layout L, R, C, LFE, Ls, Rs, plus a L and R of the Stereo mixdown. We are using Roles with Subroles to assign the tracks.

Our problem is that we failed QC because the audio in our QT Master is 6dB too low. Our audio people checked our QT Master and they also confirmed that FCP is lowering the audio 6dB compared to the ProTools master tracks.

I have read lots about things like the 'pan' rules and swithching the pan mode to 'Dialogue' but nothing has worked. I can't find any solution to importing the audio without it being altered.

Can anyone help?

John G

John, I have used the MXF output setting in FCP to export a multi-channel master and followed the instructions linked to below. Hopefully, it will help you. Part of the process involves increasing the level on imported clips.

support.apple.com/en-us/HT204261

Please let us know how things turn out. Thanks.

Thanks Dave

I have seen this article before, but I need to create a multitrack QT not an MXF. Also the change in audio level we're seeing is 6dB.

After doing a small test, our audio house said that simply raising the level within FCP by 6dB before rendering the master file is not a good idea, as this is altering the specs of their original audio tracks.

What I'd like to find out is why FCP is lowering the levels in the timeline and if there is a way to avoid it happening.

John

[Revision of earlier post. Added info regarding "pan law" bug* in FCP.]



John wrote:

I have seen this article before, but I need to create a multitrack QT not an MXF. Also the change in audio level we're seeing is 6dB.

Since you didn't go into detail about your FCP configuration, I thought that article might be helpful. The process should be the same, except for the output preset/settings. You might try outputting an MXF with your project and check the levels in the result. It's been a couple years, but when I followed the article's workflow things turned out fine.

The idea is to use that article as a guide. I can't recall why 3 dB is mentioned in the article. There may be something different about an MXF file compared with a multi-channel QT file. You could do a test with 3 dB and one with 6 dB.

However, I do know that there is a "pan law" bug in FCP (if things haven't changed since version 10.4). It causes levels to drop by 6 dB on imported clips, which is what you're seeing.

"typayton" discusses this in this article:

tpayton.com/the-pan-law-fcpx/

John wrote:

After doing a small test, our audio house said that simply raising the level within FCP by 6dB before rendering the master file is not a good idea, as this is altering the specs of their original audio tracks.

Changing the overall levels to compensate for the flawed pan law implementation in FCP *isn't* changing the balance of the mix. The audio guys need to get a life (they are being a bit precious). As long as they deliver the proper mix to you, that's the end of their responsibility. Enough said (maybe too much).

If I had had more details about your situation, or your level of knowledge about the issue, I may have suggested doing a "global" 6 dB increase on the audio and see how that works. That would be if the directions in that MXF used as a guide for your case didn't work out (you may be doing a similar workflow otherwise).

---

Of course, this situation underscores the need to test all parts of the post workflow prior to the start of post/editing. Running into this kind of issue near the end of a project can be very costly and stressful to everyone involved (it sucks).

Another option would be to export a finished, "pre-mix" version of the project as ProRes 4444 (XQ), or whatever, perhaps video only, and bring that and the mix from the audio guys into DaVinci Resolve (Studio) and marry them there for final output.

Cheers.

* I refer to the current "pan law" implementation in FCP as a bug because it's rather non-standard (and since I referred to TPayton's article).

Addendum:
Here's a good article that talks about how audio gets processed in FCP:
Is Your Audio Mix Too Loud?

I don't know why FCP decreases the volume of your tracks respect original tracks. The law pan what do your reference is important in stereo mixes but don't in multitrack 5.1 mix. I also don't understand the workflow very well with your house sound facility. It's usually the other way around, you would first edit your video attaching the corresponding audio tracks (roles of dialogue, direct sound, etc), next you send them a proxy copy both the video (with a reference timecode) and respective audio roles track (usually exported with X2Pro) . Your sound studio should take care of multitrack/stereo mixing and mastering returning to you a multichannel and stereo embedded files ready for import in your project.
Now I only see as possible solution what DaveM wrote: export video and audio tracks to Resolve and try to adjust volume, EQ etc with Fairlight tools, next proceed to export final master en QT
Good luck

John, in addition to my previous post (note some changes there), most DAWs have a choice of pan mode/depth setting. Here's an article that touches on the subject (there are others, if you're interested):

Q. What pan-law setting should I use? 

In addition to FCP lowering mono input files by 6 dB, the actual panning configuration used is a bit funky. I don't know if I understand it fully. Using TPayton's article as a reference, I played a mono clip in FCP in a stereo timeline, either with pan set to "none" or "left/right (stereo)", it was 6 dB lower than the actual level in the imported file (Oliver discusses this in his article on fcp.co). What i find a bit weird is that when I pan the clip all the way to the left or right, the volume drops another 6 dB. You'd think the signal would by raised so that the effective sound volume output would stay the same. In other words, just panning full left or full right drops the sound level I measure with a handheld SPL meter. Strange...

Anyway, this is a bit outside of your question's scope, so disregard this if you're not interested.

Hi Dave M

Thanks for your suggestions on this.

The 'Payton' article and also the 'What Pan Law Should I Use' article are new to me. I'm going to read them now.

I tend to agree, doing a global 6dB lift across all the tracks in our FCP project might be the simpelest way to go. But at the moment we're still looking for a reason why the problem is happening and if there is a proper workaround. It's odd that I've read in a few places that the 'Pan Law' bug doesn't affect mono tracks in a timeline (as we are doing) but just affects stereo projects...

Also as an alternative, we are trying out the whole workflow in Davinci Studio. We will try importing a video-only ProRes of the picture and then add the tracks and render a multitrack QT. I'll let you know the outcome.

Thanks

John

Thanks Buhardiller

I should have mentioned in my first post that the project we are doing is animation, so the entire soundtrack is created at an audio-post facility, not by us. We are just producing the broadcast master. The broadcaster asks for a multitrack QT ProRes with all the 5.1 tracks (and a stereo mix) as 8 mono tracks.

It's interesting you say that level-drop problem should not apply to 5.1 tracks. I have read this in other places. And yet we are still getting the problem with our 8x mono track project.

We are now trying Davinci Resolve Studio.

Thanks

John G

John wrote:

Thanks Buhardiller

I should have mentioned in my first post that the project we are doing is animation, so the entire soundtrack is created at an audio-post facility, not by us. We are just producing the broadcast master. The broadcaster asks for a multitrack QT ProRes with all the 5.1 tracks (and a stereo mix) as 8 mono tracks.

It's interesting you say that level-drop problem should not apply to 5.1 tracks. I have read this in other places. And yet we are still getting the problem with our 8x mono track project.

We are now trying Davinci Resolve Studio.

John,

Pretty much every DAW has an implementation or settings for the "pan law". For example, ProTools and Logic Pro offer the ability to change the amount. Fairlight in DaVinci Resolve seems to be set at a fixed -3 dB, which is often the default setting for DAWs.

Pan law in Resolve

Your audio guys should be aware of this and have an idea why FCP is possibly behaving in the way that you observed.

It seems that FCP has a fixed -6 dB compensation for mono files, which apply to "surround" channels that were created as mono tracks from the DAW. The 6 dB value is optimized for material that could be listened to, and still sound good, on a single speaker (as a fallback). Most mixing in DAWs use -3 dB, or sometimes -4.5 dB as the compensation.

So, you may find a 3 dB discrepancy in levels with your audio imported into Resolve. This might explain the 3 dB value mentioned in the Apple MXF article. I don't have anything readily available to do a verification of the article's workflow with the current version of FCP.

You may ask, "Why does this matter for a surround sound mix?" Well, the workflow mentioned in the MXF article uses a stereo timeline/Project in FCP.

As I mentioned earlier in the thread, FCP isn't "messing with the mix", it's just applying it's chosen signal processing method to imported mono track/channel audio.

-Dave

P.S. - In the future I'm going to be sure to ask the audio dept. about their pan law setting, or at least keep it in mind, when testing any finishing/mastering workflow. A "pan law" question might be a way of assessing the technical competency of the audio dept. At the very least, it might be something that should be specified for audio deliverables, depending on the application used to marry the final mix to picture...

Hi DaveM
You are right about how pan law is modified on -3dB for stereo mix and -6dB for mono mix. But is important to understand the pan lawing are based in acoustic has two speakers emitting the same signal at the same level and how a listener on the central plane will perceive this volume. For mix in stereo the listener will perceive the sound above +3 dB and sound mixed in mono and emitted by two speakers will be perceived just below -3dB. Important!: this only affects sound emitted with two speakers in left and right position.
What about in multichannel 5.1, 7.1,...etc mixes?. It's very important that mix has to be monitored according to loudness recommendations (integrated LUFS, True peak, Range) and this is only possible to do with DAW pro. I use Nuendo but LogicPro and (of course) Protools are other alternatives. I have never used Fairlight but I think has these features. But FCP it's not the best option for this job

Buhardilla wrote:

What about in multichannel 5.1, 7.1,...etc mixes?. It's very important that mix has to be monitored according to loudness recommendations (integrated LUFS, True peak, Range) and this is only possible to do with DAW pro. I use Nuendo but LogicPro and (of course) Protools are other alternatives. I have never used Fairlight but I think has these features. But FCP it's not the best option for this job

I totally agree. I am not an expert in using FCP this way. I did some handling of surround mixes but that was mostly with FCP 5 through 7. Back then, Compressor was a lot less opaque with more functionality exposed to the user (more settings). A couple of years ago, I used the "MXF export from FCP" article from Apply as a guide to create a handful of surround outputs. I followed the directions and the outputs were tested in-house by the client before submission.

I believe that the 3 dB change for multi-channel surround mixes (mentioned in the article) may have to do with downmixing attentuation that occurs as part of the MXF format specs.I don't have a project readily available to do testing. As I mentioned earlier in this thread, for the OP's situation, I'm not sure if following the same procedure as prescribed in the MXF article (but saving as a multi-channel QT file) works properly.

There are some surround-compatible metering plugins available that might be helpful when doing this in FCP, if they work in more recent versions of FCP.

This process is rather difficult because FCP/Compressor do many things behind-the-scenes that are not documented well, if at all.

As you implied, you need to meter the varioius parts of the workflow to make sure things turn out properly (loudness specs, etc.)...