TV Broadcast, Mixing Levels, Commercials, Tech Specs

Question

I generally work in film. I have a broadcast gig in which I am cleaning dialog and mixing a 23 minute spot which is going to air shortly and I do not have a Technical Specification Sheet. I am so sorry to ask these questions again (i know versions of this question have been asked), but I just need clarification and I have additional questions...

1. Is it correct to calibrate system to 79 dB-spl (at -20) for TV broadcast? More Importantly - Are commercials and shows mixed differently, or at different calibrations? (I understand each station may have different specs making this a difficult question).

2. Is it correct that I mix, Peak at -10db, and -20db for unity gain?

3. 79 db sounds seemingly quiet. Do TV stations generally take these mixes and compress and squash them to be louder before airing? Or do I need to do an extra step after mixing?

Answer 1

I'm not a great authority on this, but i'll jump in anyway because you seem keen to get an answer:

1. 79 dB spl seems to be the standard calibration for TV mixes. Commercials, from what i hear, tend to be pushed louder by ad agency execs who want their ad to thump people in the face, but it sounds like you're mixing a program so you should mix to standard spec (the ads are pretty much what pay for the show you're mixing, so i imagine they get rejected less often).

2. Yes to -10dBFS peak. I'm not sure i understand your use of unity gain in this context (probably my fault), but the most common broadcast spec for average loudness is -24dB LKFS. If you have Dolby Media Meter, or can borrow it from someone, use that to monitor your average loudness. If you can't get hold of it, you can get Phase Scope for free (sorry i can't provide a link off the top of my head, but i'm sure google will help). Put it on your master, click the LEQ(A) button in the bottom panel of the plug in and set it to analyse 10 seconds. If you keep your reading between -29 and -25 dB (averaging around -27), you should be in the correct average loudness range.

3. Loudness is all subjective. It might seem quiet to you if you're used to mixing at a louder calibration. I believe the -79dB spl for tv is to allow for the noise and distractions of peoples' homes. This will push you to maybe compress a little more, and to lift the subtle details so they come through. It's a smaller dynamic range, but i think it's practical, given TV viewing conditions at home. Just make sure you don't push your average level too high.

Hope that helps. Best of luck!

Answer 2

First off this 79 figure is based on room size. Look for the ATSC 85 document to verify. It's typical to mix to 79 for TV and 82 to 85 for film. Theatrical get's sometimes 85 up on LCR and 82 on Ls Rs.

You need to take a room size measurement then using the figures in the doc above, and an SPL meter and the blue sky test tones (or pink limited mono wav files) calibrate each speaker individually from the mix position with the spl meter facing 45 degrees up.

I work in a bedroom and mix to 76dbspl.

this means that the pink noise file playing from my pro tools is mixed at -20dbspl and as it's playing out of my monitor controller i turn up the volume on till my spl meter reads 76. then, as a base i leave that volume knob set and check each speaker after that and turn the volume on the speaker itself to get each speaker to 76. all individually.

i use 76 for TV related stuff and 80 for film.

Best is to mix a little TV related stuff and a little film related stuff - both to your taste - then take that to a dub stage and put it up for a few minutes and hear whats happening.

http://www.gearslutz.com/board/post-production-forum/604616-speaker-calibration-tutorial-students.html