TV Broadcast Levels

Question

I just mixed a documentary for TV broadcast and the clients told me that it should not peak higher than -6db and the reference tones should be at -12db. I did just that but then when they where dumping down to DVCPRO for broadcast, turns out they had to drop the mix another 4db. Apperently they went through Digibeta first, could they have messed up the levels there? I wasn't there to check though so I'm wondering if it's on my side or theirs.

Anyone with similar experiences or expertise that could maybe share some info?

Thanks!

Answer 1

Going to expand Georgi.m's comments....

The UK use PPM to check levels, he's right about PPM6 being as high as you can go. If you output 1KHz tone at PPM6 it should equal -10dB on a VU (I use an RTW Portamonitor).

From the BBC specs "Peak sound levels within the programme must not exceed PPM6: that is +dB with respect to the reference level of -18dBFS". Your tone should be 1KHz -18dBFS/PPM4. It will start at 09:58:30:00 and finish at 09:59:30:00.

We work in NTSC as well as PAL, and the tone here is -20dBFS/PPM3.5, at 00:58:30:00 to 00:59:39:00. I've only ever mastered NTSC to Digibeta where the top limit is normally -10dBFS. That gives headroom for extremely brief peaks above -10 as at digital meter like an RTW will react much quicker than a PPM which has a relatively slow response. Mastering to HDCAM/HDCAMSR is the same as Digibeta PAL/NTSC respectively.

I've not come across any broadcast specs that are so high. In fact the likes of Discovery/PBS are lower than that and would use another type of meter.

Answer 2

Hi

just thought I should post this graph from Adtoox, it is very useful when working with PPM vs dBFS and VU.

http://twitpic.com/122j1c

For commercials and promos broadcasters all have different specs, some refers to the dBFS scale, some to PPM and for example commercials for Adtoox have these requirements:

"No programme peak is allowed to exceed +4 dBu using a PPM meter with the EBU digital scale...The commercial's loudness should be within the range of -22 to -18 dBFS according to Leq (A) (IEC 60804), measured with Dolby LM100 in short mode, digital input."

Full specs at: https://ecexpress.adtoox.com/help/data/Robohelp/!SSL!/WebHelp/File_Technical_Specification.htm

Peter

Answer 3

Perhaps they had their specs wrong? Most but not all US stations require peaks limited to -10... Which network is it airing on?

Answer 4

In my honest opinion -12dB tone for allignment seems too high for me assuming that nominal programme level will be around this tone level. If the original -12dBFS tone was passed to DigiBeta without analog conversion it should have mantained these level to DigiBeta. Common allignment levels (and nominal programme levels) for DigiBeta are -20dBFS (SMPTE) or -18dBFS (EBU). Not sure but it sounds like they were asking to you a "NLE" signal level that, when passed to a DigiBeta recorder resulted too hot.

When NLE and non-betacam cameras came into play we had to talk with editors in order to keep our levels the same. For example, Final Cut Tones were by defect at -12dBsFS and this was the nominal programme level editors used, so their work used to sound hot when going to transfer to Digibeta.

In my experience I´ve found 2 kind of problems regarding levels (3 if you have both them):

1. signal mantains digital from source to destiny. Recommended allignment levels for digital interexchange of material can vary from USA to Europe, for example, but it is easy to find out wich standard has been followed just by checking tones.

2. signal is converted digital to analog or viceversa in some stage. There are 2 main recommendations for analog to digital conversion values so the allignment issue can be tricky in this case. For example, a -12dBFS tone is recorded in a SMPTE DigiBeta VTR, then its analog outputs are connected to analog inputs of an "EBU adjusted" VTR recorder. The second one will meter -6dBFS. Of course, it is not your case.

Anyway, both of this main recommended allignment levels are near each other (-20 and -18dBFS) so -12dB would be too high for each of them.

We have had some level issues in the last years since part of our signal chain was analog and the other was digital; some of our equipment was analog and some digital.

For international material exchange I´d recommend reading: ITU-R BS.1726, ITU-R BR.777-3

For analog to digital conversion levels: SMPTE RP155, EBU R.68, ITU-R BS.645-2

My English is not as good as my Basque or Spanish, but I hope this helps.

Answer 5

I recently did a short programme for TV to UK standard (PPM 4 -18dBFS ref, PPM 6 max). The video had no bars or countdown (nowhere to put tone at reference level?), so I included a separate file with 10sec of 1khz tone at reference level, just to make sure..

Answer 6

well it's a question really.

Do you make sure the mix down doesn't peak above -10 Db for instance, or do you you mix so that each element IN the mix doesn't peak at -10 Db?

I would think you want the mix to be as loud as possible (max 0 db), then take the mix down and export it so that it doesn't peak at -10.

I'm only asking because I start mixing what I recorded for a TV pilot tomorrow and I imagine their broadcast level is +/- -10 Db. If that isn't the case I can just change it, but I would need conformation with regards to making the mix not peaking -10.