Editing for broadcast - tips on hitting these tech targets?

[bigass]

Heya, gang. I've spent the past two decades of my career in radio. Last time I was involved seriously in broadcast was in the days of tape. I'm no slouch with video, but my output has been for my own entertainment and YouTube consumption, where the rules are that if it looks good and works, it's good.

Now I'm working on a TV series for broadcast. The broadcaster has provided me its technical standards. Most of them are obvious enough for me to conform to, but there are two things I'm seeking your advice on.


First:

DigitalAudio Standards – 18dB Average. No peaks over -15 or valleys under -25.

I've always worked with the 'Price Is Right' rules -- closest to [0db/the actual retail price] without going over -- with the philosophy that all's fair if it doesn't clip and sounds loud enough but not so loud that it's annoying.


In Vegas, how would you recommend reaching the broadcaster's standard? Mix like I ordinarily would and pull the master down to -15, or mix with my monitors turned up and an eye toward -18 with some kind of effect chain at the end to ensure compliance?


Second:

DigitalVideo Standards – 0 IRE Black Level - 100 IRE Peak

It's been 20 years since I learned about IRE and now it sounds foreign to me. Is IRE even a thing in digital? (Kind of a rhetorical question.)


I guess my question here is -- do I need to do anything special here, or is standard Vegas output going to be fine? Or do I need a Computer-RGB levels filter or vice versa...?


Thanks in advance for any advice that might come from this.

[smrpix]

The basic process is the same for video and audio.

For video, use your scopes while you color correct to get in range and achieve a pleasant look, then add the Broadcast color filter to clip off any strays. (legalize)

Same with audio, make a nice mix with -18 as your target, then add a hard limiter to -15.

[bigass]

The basic process is the same for video and audio.

For video, use your scopes while you color correct to get in range and achieve a pleasant look, then add the Broadcast color filter to clip off any strays. (legalize)

Same with audio, make a nice mix with -18 as your target, then add a hard limiter to -15.

I remember that 'broadcast legal' colors were a big concern with NTSC -- if the reds were out of range, peoples' speakers at home would buzz, or something -- but is that still so with digital? I mean, if it's within 0-255, is it not fair game?


I'm going to have to take a crash course on scopes. I have memories of using a tiny screwdriver to adjust pots on something to to set up a camera with a vectorscope...but seem to recall using color bars to do that. Using scopes to bring already-recorded material to a conforming state is out of my knowledge right now.


Thanks for the tip on the audio -- mix with -18 in mind then hard-limit to -15 to catch strays. Anything I need to worry about on the bottom end? No valleys under -25?

[Brad]

I mean, if it's within 0-255, is it not fair game?

Can't speak to the other questions, but you need 16-235 for luma and 16-240 for chroma. I don't know about Vegas, but Premiere's scopes display IRE units anyhow.

Isn't the relevant audio filter Compression rather than a limiter, to squash the dynamic range at both ends?

[smrpix]

I mean, if it's within 0-255, is it not fair game?

Can't speak to the other questions, but you need 16-235 for luma and 16-240 for chroma. I don't know about Vegas, but Premiere's scopes display IRE units anyhow.

Correct, for broadcast, 0-255 is NOT legal. 16-235 RGB. FWIW 0-100 ire is more common in Japan, 7.5 -100 in the rest of the ntsc world.

Isn't the relevant audio filter Compression rather than a limiter, to squash the dynamic range at both ends?

Yes, compression squishes the dynamic range so the softer and louder parts are closer together, hard limiter forces a cutoff at a pre-set level (some more gently than others.) The two can be used separately or in conjunction.

[bigass]

Correct, for broadcast, 0-255 is NOT legal. 16-235 RGB. FWIW 0-100 ire is more common in Japan, 7.5 -100 in the rest of the ntsc world.

Okay, so if I follow that... my workflow in Vegas would be to edit normally, then put a Computer RGB to Studio RGB levels effect on the output, to re-map the 0-255 to 16-235.

Yes, compression squishes the dynamic range so the softer and louder parts are closer together, hard limiter forces a cutoff at a pre-set level (some more gently than others.) The two can be used separately or in conjunction.

That's where my confusion sets in, I think. I'm no stranger to compressors, but I usually go for what sounds good rather than what's within certain tech specs. So, a -15 limiter is a no-brainer. But what settings might I start with to move the rest of the audio to a -25 to -19 range? I'm sure I could figure it out with a pencil but if you have the answer on the tip of your tongue/fingers.....

[smrpix]

I usually go for what sounds good rather than what's within certain tech specs. So, a -15 limiter is a no-brainer. But what settings might I start with to move the rest of the audio to a -25 to -19 range? I'm sure I could figure it out with a pencil but if you have the answer on the tip of your tongue/fingers.....

I'm kind of confused by this question. You use the normal mixer and watch your meters, not sure how a pencil figures into it.

You probably know this stuff already:
http://vimeo.com/41583959

[bigass]

I usually go for what sounds good rather than what's within certain tech specs. So, a -15 limiter is a no-brainer. But what settings might I start with to move the rest of the audio to a -25 to -19 range? I'm sure I could figure it out with a pencil but if you have the answer on the tip of your tongue/fingers.....

I'm kind of confused by this question. You use the normal mixer and watch your meters, not sure how a pencil figures into it.

You probably know this stuff already:
http://vimeo.com/41583959

Yes, I didn't phrase that very well.


If my range is supposed to be between -x and -y, I understand how to aim for a good top limit and put an absolute cap on it to catch any stray transients... but a compressor to bring the rest up to the recommended bottom end -- that's the setting I'm curious about. Again, if I'm being told that the requirement is an average -19 with nothing over -15 and no "valleys" under -25, I can grok aiming for -19 in my mix and putting a hard limit on -15.... the -25 "valleys" is what puzzles me.

[smrpix]

Ah, I see.

Honestly, I've never heard of a requirement like that before, and I can't imagine how they would enforce it on say a fade to silence. Maybe they mean normal speech shouldn't drop below that range, or a music bed under speech shouldn't be below that.

I often use pretty heavy compression ratios (for speech only) of 8:1 or 10:1 for pieces that are going to be seen on the web or played on mobile devices, often with some gain added to bring up the floor, if that's any use.

[bigass]

Yeah, I'll ask my contact at the broadcaster for more on that requirement. Thanks for your input.

After some of the feedback yesterday, I dove into a color-correction tutorial for Vegas. It's amazing how far one can go in a certain field without covering some of the basics. I've made some great videos, but I can't help thinking how much better they could've been if I'd had a better understanding of using the scopes. That's the great thing about this hobby/business -- always more to learn.

[smrpix]

Glad to help, good luck.

[Cornucopia]

There must a misunderstanding somewhere (likely in their statement), because if most audio programs' signals are narrowed to a 10dB range of dynamics, they'll all sound like SHIT!

What audio format is this referring to? Maybe, if it uses AC-3 for example, it's referring to a DialNorm exemplar setting.

The whole -18 & -15 are quite straightforward and commonplace: You set -18dBFS as your 0VU reference level, with (gak!) -15 as your hard limit threshold (way too close to really sound good, but that's broadcast for you). Then, run all your program to peak up to ~0VU.

Scott

[bigass]

What audio format is this referring to? Maybe, if it uses AC-3 for example, it's referring to a DialNorm exemplar setting.

The whole -18 & -15 are quite straightforward and commonplace: You set -18dBFS as your 0VU reference level, with (gak!) -15 as your hard limit threshold (way too close to really sound good, but that's broadcast for you). Then, run all your program to peak up to ~0VU.

Format-wise, here's what's requested:
Mpeg2 – MXF Wrapper - 1440x1080top-field - (60i) 59.94 FPS 35MBPS
PCM– 48000 – Dual Mono – 16bit


... I didn't look closely at that -- dual mono -- think I should assume that's the same program on both tracks, rather than stereo? (Probably wise not to assume anything, actually.)


As for setting -18dBFS as 0VU -- 'k, you've got me on that one. I don't have Vegas open in front of me right now, but I don't remember a way to make that kind of change. Probably straightforward if you're putting it to me that .....straightforwardly.

[Brad]

Unless they're totally insane that should mean 2 channels of audio with different content on 2 different mono tracks, as opposed to one "stereo" track.

[Cornucopia]

Often, the term "dual mono" in that context can refer to the applicability of the tracks to be accommodating of 2 separate mono tracks AS WELL AS stereo, and also with the idea that the compressed bitrate would NOT be interlinked (as it can be with stereo compressed tracks). Of course, being LPCM audio, that is a moot point.

Notice that these kinds of specs are REGULARLY put out not by the CTO or a tech team, but by the sales/marketing team, which got it 2nd-hand from the techs. So they're flubbing it up by mixing up or misusing terms. I can think of no less than 6 times that people have come on this site with the same kind of problem, just to find out the correct info once they've contacted a reliable tech employee.

Scott

[bigass]

... got a reply back from the master control supervisor at the broadcaster.

"yes on the 10db range andthe mono track duplicated to left and right."


So, any visions I had of doing a beautiful stereo soundtrack shall be abandoned....or at least saved for the DVD release.


The 10db range, well, I'll still need to figure that out.

[Cornucopia]

Compressor, Heavy duty ratio, Threshold set either @ highest or lowest (depending upon how the compressor is set up), level/gain to raise to the necessary range. Good luck. That dude has GOT to be meaning long-term RMS values and not Peak/Instantaneous!

To get it right, you could test out sine tones at calibrated levels and see where the output falls.

What broadcaster is doing that?!

Scott

[bigass]

Compressor, Heavy duty ratio, Threshold set either @ highest or lowest (depending upon how the compressor is set up), level/gain to raise to the necessary range. Good luck. That dude has GOT to be meaning long-term RMS values and not Peak/Instantaneous!

To get it right, you could test out sine tones at calibrated levels and see where the output falls.

What broadcaster is doing that?!

It's a community television station -- the cable company's channel. The guy giving me the specs is the assistant manager of master control... I presume he's someone who's been given material from producers that's not fit for air.