Nat-Geo True Peak for 5.1

[wheresmyfroggy]

Having read through the latest Nat-Geo spec for 5.1 delivery before starting a major series, I was glad to see that the 5.1 mix was given more headroom, being able to go up to -2 truepeak. So we took advantage and mixed the 5.1 utilising that extra headroom.....Yay!

9 episodes later, without any rejections, we get a note in the record report on one episode that says:

"on Dolby Full Mix tracks 1-3 PEAK levels register high @ -5 dbfs throughout. Ideal PEAK levels are @ -10 dbfs"

Although they have not failed it, have we taken this new freedom too far and its taken them 9 episodes to notice?

Please let me know how you approach Nat-Geo 5.1 mixes...

[soundworx]

I discussed this with a very nice guy at NatGeo's QC Washington. My question was, if I actually used the headroom to -2 truepeak on the full mix, it would be very hard to ALSO get a decent sounding stereo mixdown. I got this answer:

"The level question is a little more complicated. Because our 5.1 and stereo mixes are used in different ways around the world, we need them to meet certain specs to please all of our regions at the same time. This necessitates a blending of the old analog specs and the current digital standards. While the NGC spec allows for 5.1 stem peaks to -2dbfs, a -23 db LKFS 5.1 mix that peaks at -2 dbfs will be well over the -10 dbfs peak requirement for the stereo mix when downmixed. Having a -10 dbfs peak on the stereo mixes is important for our regions that still broadcast the stereo mix as an analog signal. Keeping the average level the same between the 5.1 mix and the stereo mix allows other regions use the stereo mix as a SAP option without a noticeable change in volume. To achieve the spec here in house, we generally limit our 5.1 stems to -10dbfs so that a stereo downmix will peak close to -10 dbfs. This way, no one limiter is doing too much work."

There you have it... Now try and convince the director that louder isn't always better ;-) Seriously, put a really good limiter on the stereo mix and doublecheck the loud parts when you're done with the 5.1.

Originally Posted by wheresmyfroggy

Having read through the latest Nat-Geo spec for 5.1 delivery before starting a major series, I was glad to see that the 5.1 mix was given more headroom, being able to go up to -2 truepeak. So we took advantage and mixed the 5.1 utilising that extra headroom.....Yay!

9 episodes later, without any rejections, we get a note in the record report on one episode that says:

"on Dolby Full Mix tracks 1-3 PEAK levels register high @ -5 dbfs throughout. Ideal PEAK levels are @ -10 dbfs"

Although they have not failed it, have we taken this new freedom too far and its taken them 9 episodes to notice?

Please let me know how you approach Nat-Geo 5.1 mixes...

[wheresmyfroggy]

We always review the Stereo mix at layback to tape as that's what the lions share of the viewers will hear. And even with the 5.1 peaking at -6/-5 the stereo sounds great peaking at -10 and switching between the two mixes is not a drastic change, its amazing what a bit of clever compression/limiting can achieve...


...Anyway. I have just received a new spec, which is for want of a better word....vague! switching between 5.1/stereo requirements without explicitly compiling them in separate sections....

Oh well, it was fun while it lasted, my main problem with peaks at -10 is that the dialogue is centre channel only, and to achieve -23 dialnorm means serious compression, but I also notice that on this new spec the dialnorm has dropped to -24, which may help a little. I wish they would make their minds up

[soundworx]

Didn't know they switched from LKFS to Dialnorm?

Originally Posted by wheresmyfroggy

Oh well, it was fun while it lasted, my main problem with peaks at -10 is that the dialogue is centre channel only, and to achieve -23 dialnorm means serious compression, but I also notice that on this new spec the dialnorm has dropped to -24, which may help a little. I wish they would make their minds up

[wheresmyfroggy]

Originally Posted by soundworx

Didn't know they switched from LKFS to Dialnorm?

Sorry, yes that's what I meant...

[tom_lowe]

Originally Posted by wheresmyfroggy

Sorry, yes that's what I meant...

Dolby still call it DialNorm on their encoders and decoders. LKFS is just the name given to the units loudness is measured in.

[soundworx]

I'm not an expert, but from what I understand Dialnorm is the measured speech WITHIN a mix, while LKFS measures everything. Depending on your program, the LKFS and Dialnorm readings of the same show could be very different, it's not the same thing... But I think Dialnorm is a past station?

Originally Posted by tom_lowe

Dolby still call it DialNorm on their encoders and decoders. LKFS is just the name given to the units loudness is measured in.

[wheresmyfroggy]

Originally Posted by soundworx

I'm not an expert, but from what I understand Dialnorm is the measured speech WITHIN a mix, while LKFS measures everything. Depending on your program, the LKFS and Dialnorm readings of the same show could be very different, it's not the same thing... But I think Dialnorm is a past station?

Tom Lowe is quite right, I just doubted myself when you made your post.
Dialnorm is the term given to the required LKFS reading as encoded into the Dolby-e stream.

[Postman]

NGT specs for 2011 are self contradicting. For a 5.1 mix, one paragraph states true peaks up to -2dbfs are allowed. Later, another paragraph states -6dbfs. So, depending on which paragraph you choose....

Last month I sent them a 5.1 that peaked at -3dbfs and got rejected because of the levels. After several phone calls, including my client's project manager and the QC engineer, they realized their new specs are contradictory. They then accepted the 5.1 mix as is with -3dbfs and I haven't heard anything else about it. It wouldn't surprise me if they just ran my mixes through a clipper to hack off the few extra dbs.

You might want to double-check on -2 vs. -6. In the past I've limited my 5.1 to -10dbfs for NatGEO. This year I kept the dialog at -7 on the center (which downmixes to -10). It was a couple of sfx bumps that pushed to -3. Frankly, if those sfx get clipped during analog distribution, they'll probaby sound even better!

[soundworx]

I think the keyword in this confusion is "Dialogue Intelligence", which was/is also called Dialnorm at some point. Enough of this, it's all just a way to measure how good it sounds to a person who doesn't know how to listen for such things. (Thanks B!)

Originally Posted by wheresmyfroggy

Tom Lowe is quite right, I just doubted myself when you made your post.
Dialnorm is the term given to the required LKFS reading as encoded into the Dolby-e stream.