FCP’s audio meter

[Michael Gissing]

Jeremy, I didn’t see any mention in Isobel’s case that there was a need for a broadcast spec delivery. If it was simply for projection or DVD, then again, no need to change levels to broadcast spec. It should be remembered that dropping a 16 bit signal down by 10 db is effectively only using about 10bits of the signal. It has always irked me that the reason we throw away the best part of a digital signal is because Sony arbitrarily set -20db as a 0VU equivalent on their first digital machines. The lack of headroom in analog audio routers is why broadcast spec chose a -10db max. In our modern digital world, there is no longer a need to do this but it persists (a bit like 29.97 and DF NDF madness).

Using digital to its full range is preferred when not dealing with broadcast spec. Digital sound for feature films can use the full range as CD audio does, so you create issues for mastered files if you drop the levels. It can effect the way audio fades into its noise floor.

A lot of work goes into dithering to make smooth fades into noise floors on full range signals and you can change that by doing a simple gain reduction if FCP. At least FCP uses floating point calculations so that is not a tragedy.

[Jeremy Garchow]

[Michael Gissing] ” If it was simply for projection or DVD, then again, no need to change levels to broadcast spec.”

Agreed. I also think that Isobel thought the file is clipping but it in the sample Isobel sent, there was no clipping. Sure the levels go all the way to the top, but the little clipping lights do not come on.

So, what do you do with the stock tracks?

[Michael Gissing] “In our modern digital world, there is no longer a need to do this but it persists (a bit like 29.97 and DF NDF madness). “

It’s not quite all digital yet. There’s boat loads of analog gear out there. We will be dragging that legacy around for a long while.

Also, if you downloaded Isobel’s clip does that sample clip in FCP for you? It doesn’t for me which makes me think there’s something wrong with the setup.

Just calling it like I see it, sorry if I am dragging this out.

Jeremy

[Michael Gissing]

[Jeremy Garchow] “So, what do you do with the stock tracks?”

That’s very different. If you are adding material like dialog to a music underscore, then of course you have to mix it.

I am currently playing out a few copies of a doco to digi beta so I can’t check my FCP for meter clipping at the moment. Personally, I don’t use the FCP meters as a definitive guide. It isn’t a serious audio editing & mixing tool so unlike the waveform & vectorscope, I am less concerned at a non standard, but probably safe, calibration.

[Jeremy Garchow]

[Michael Gissing] ” I don’t use the FCP meters as a definitive guid”

Agreed, the FCp audio meters aren’t the best. Jsut wanted to see fi it clips in your program is all.

[Tom Wolsky]

“If it was simply for projection or DVD, then again, no need to change levels to broadcast spec.”

This seems to presuppose a very narrow meaning to broadcast. In video anything that’s destined for display on a television set should conform to broadcast specifications for luminance and chrominance for display on that medium. I have always been puzzled by the “standards” in audio, where there seems to be no standard. I’m not sure how you can speak of a standard when there appears to be standards for broadcast, standards for digital video, for Sony digital video, ‘for projection or DVD,’ for music recording, for radio. What’s the standard? What’s tone set to, and what does tone mean in terms of mixing?

Presumably in this case the music is mixed to and recorded for CD delivery, while the video editor synchronizing the material has to deliver it to what?? The same CD delivery specification? Digital video? Broadcast? Sony theatrical? Do you have to do a different mix for every delivery medium? What’s the standard? Is there one?

All the best,

Tom

Class on Demand DVDs “Complete Training for FCP6,” “Basic Training for FCS2” and “Final Cut Express Made Easy”
Author: “Final Cut Pro 5 Editing Essentials” and “Final Cut Express 4 Editing Workshop”

[Nick Price]

Hi all,
lots of great knowledge flying around here, but the simple fact is that for broadcast (or even dvd production if you are being careful) audio levels should stay between levels determined by the channel, which usually are between 4 to 6 on a PPM, and -18 to -10 on a vu meter, like FCPs. And music should generally sit around 5 on a PPM, no more than -12 on a VU meter. So just turn it down. There wont be any quality loss(!). That is the editors job (or the dubbing mixers if you have one).

So rather than go on about how accurate FCP meters are, calibrate them with an external tone source and a PPM, and then use the meters in FCP. For what its worth i find the FCP meters extremely accurate. I don’t really care if they aren’t accurate at the high end cos you should never be delivering audio that high for broadcast, unless you want it rejected.

If the music is mixed right then turning down is fine.
best wishes
nick

[Michael Gissing]

[Nick PRice] “between 4 to 6 on a PPM, and -18 to -10 on a vu meter, like FCPs. And music should generally sit around 5 on a PPM, no more than -12 on a VU meter. So just turn it down. There wont be any quality loss(!).”

PPM meters are a not accurate for a digital world. They are not a reliable measure of loudness, nor a really useful measure of peak levels. You mean dbfs not VU. -20dbfs = 0VU. Your comments are inaccurate and confusing.

If you “turn it down” it does effect the quality as you are reducing the effective bit rate. If you don’t understand this then please don’t pass comment.

To answer Tom. Tone is basically irrelevant in a digital world. Its purpose was to calibrate analog machines. In the NTSC world we provide -20 dbfs 1khz tone because they ask for it. In PAL it is -18dbfs 1 hhz tone because that’s what they want.

Broadcasters have chosen a maximum peak of -10dbfs. For DVD release there is no such limitation. Features films exceed the -10dbfs peak scale as does music DVDs. It isn’t the job of FCP editors to readjust a mastered final audio track unless they are providing versions for multiple markets including broadcast & DVD.

My job running a facility that does both audio mastering and FCP onlining is to make versions for those markets including cinema release. They all have subtly different requirements which a simple level tweak in FCP is not the right approach.

I don’t know why there is so much muddled and confused information and misunderstanding about audio. I do however appreciate this lack of understanding as I have had a long and distinguished career as a result.

[Nick Price]

Thanks for your comments Micheal although i have to say that you dont clear things up very much. This was a practical question that had a simple answer really.

Delivering to broadcasters require certain limitations. If thats what they require then turing it down is what you have to do. As a jobbing editor who frequently has to deliver mastered audio for broadcasts, and non broadcast dvds, often without the always useful dubbing mixer, you have to have practical knowledge of what to do in these circumstances.

Saying it isnt the job of FCP editors to adjust final music masters is ridiculous. An editor mixes the sound as best he can. If that means turning the music down so it doesnt go over the specified -10 then so be it. Quality loss wont come into it anyway cos you will only hear that if you turn the music back up again.

Sorry for the VU/dbfs mistake. that what comes if you try and do too many things at work at once!
Hope Isobel can glean useful info from something here.
Nick

[Michael Gissing]

[Nick Price] “Saying it isnt the job of FCP editors to adjust final music masters is ridiculous”

I said “Mastered final audio track”. I already clarified with Jeremy the difference between mixing audio during and edit and dealing with final mixes dropped into an FCP project for final outputting.

[Jeremy Garchow]

[Michael Gissing] ” I already clarified with Jeremy the difference between mixing audio during and edit and dealing with final mixes dropped into an FCP project for final outputting. “

And in ISOBEL’S CASE…you know the one this thread was started on, It is okay for her to ‘turn it down’ for broadcast. Michael, you have admitted it, I have admitted it. She did not receive a final mastered broadcast mix, she received a final CD mix.

I think we are now going off on two different strings here.

Jeremy