WE TV -10 limit on a 5.1 mix?

[Brandonx1]

Hi All,
Does this spec make any sense anyone? They want their 5.1 and stereo mix to be -10. This seems really wrong to me. Any thoughts?
Best,
Brandon

[paranerd]

I agree with you. It seems wrong.

[Henchman]

Originally Posted by Brandonx1

Hi All,
Does this spec make any sense anyone? They want their 5.1 and stereo mix to be -10. This seems really wrong to me. Any thoughts?
Best,
Brandon

I'd that's what they want, then its right.
If that's In their spec sheet, then just mix it that way.
It's not the first broadcaster I've seen with that spec.

[Brandonx1]

Originally Posted by Henchman

I'd that's what they want, then its right.
If that's In their spec sheet, then just mix it that way.
It's not the first broadcaster I've seen with that spec.

It's the first one I've seen with that spec. Also, I'm just concerned about the down mix and overly compressing the DX to fit in that range. It'll be a very quiet or very compressed 5.1 and stereo downmix. I'm complying I just don't like it.
Thanks all,
Brandon

[Tstein]

By -10 do you mean -10 dbfs. This is or was a typical old school analog TV spec, used by lots of broadcasters. The 10 db of head room allowed for High Frequency pre emphasis and de emphasis curves.

It's a bit outdated, but like Henchman said if thats the spec...

Ted

[TVPostSound]

Same as Showtime.
A. When viewed using analog metering equipment, peak program levels shall not exceed +14dbu (which is +10db above 0 vu whereas 0 vu = +4 dbu). Peak program levels shall be determined by using a Peak Program Meter (PPM). VU meters are not to be used to determine Peak Program Levels (PPL).

When measured using digital metering, 0 reference is defined as -20db down from the maximum full-scale digital level (dbfs) allowed by the AES/EBU digital audio standard of the tape machine. I.E. reference = -20dbfs.

1. Average program level (Absolute level) shall not exceed 0 vu reference except for occasional peaks normally present in movie soundtracks.

2. Peak program level should not exceed +14dbu (which is +10db above 0 vu whereas 0 vu = +4 dbu).. Peak distortion (THD) shall not exceed 1% at +14 dbu.

[bdangler]

I would read that to mean they want the stems to peak at -10 dbfs. Average volume would be another matter. Isn't -10 dbfs the NTSC standard peak level?

[diamondschwin]

I dont know why it seems so wrong... very typical spec especially if they have any analog stuff left in the broadcast chain. A lot of 5.1 specs are now calling for peaks to not exceed -3 since digital has taken over but that doesnt mean you have all your dialog in the center channel sitting up that high (or music or SFX for that matter)


is there a dialnorm spec? because technically you could easily not cross -10 on the center channel with a -27 leqA or ITU Spec

[Brandonx1]

Originally Posted by diamondschwin

I dont know why it seems so wrong... very typical spec especially if they have any analog stuff left in the broadcast chain. A lot of 5.1 specs are now calling for peaks to not exceed -3 since digital has taken over but that doesnt mean you have all your dialog in the center channel sitting up that high (or music or SFX for that matter)


is there a dialnorm spec? because technically you could easily not cross -10 on the center channel with a -27 leqA or ITU Spec

Their are a couple of reasons mixing a 5.1 show at the same peak level as the stereo mix feels wrong.

Firstly, 5.1 audio is broadcast as ac-3 and their for is digital. So, no need to limit it. I like to make my TV shows a dynamic as possible. It sounds better to me.

Secondly, in a typical 5.1 mix, the dx is almost entirely in the center channel. To downmix into stereo, the center is dropped 3 dB and added to the left and right. So, in most cases, the stereo downmix will have peaks -3 dB lower then the 5.1. So, if the 5.1 has peaks at -10 the stereo will peak at -13. That's a crushed mix unless I mix the whole show lower and then it will be quiet.

Just try to mix a 5.1 program in a calibrated room. Without hitting compression too hard at -10 dB. Sounds quiet to me.

Best

[Postman]

NatGEO has the same limit, -10dbfs peak on all mix channels stereo and surround with dialnorm of -24leqA (it was still leqA last year, maybe they are LKFS this year I don't know yet). I made the mistake of thinking the spec must be wrong, that they must be talking about the stereo mix only, and I let my center peak above -10. And I got slapped for it.

I was told some of their broadcast infrastructure is still analog and therefore they need to keep that headroom spec in place. Personally, I think it is just another way to absolutely guarantee the mix has no dynamics.

Just hit the specs and move on.