Turtlerock Forum

Hey Guys,

So - TC have released research that states that the ideal loudness level for mobile devices is -16LKFS, as opposed to the -24dB LKFS that is the standard for HD television transmission.The standard is called OP59 in Australia, you can read it here:

http://www.freetv.com.au/media/Engineering/OP59_Measurement_and_management_of_Loudness_in_Soundtracks_for_Television_Broadcasting_-_Issue_1_-_July_2010.pdf

Interestingly, Apple's own "soundcheck" algorithm used in all their iDevices is also set to -16dB, they use a proprietary algorithm, not LKFS. Anyway, the consensus seems to be that -16dB is the appropriate level loudness when listening to a mobile device in a potentially noisy environment.

TC have put out a whitepaper detailing this here:

http://www.tcelectronic.com/media/2040040/mobile-test-paper-2013.pdf

One of the things that the white paper stresses is that there is no need for an additional "mobile" mix, I read almost as if they expect that an automatic process will be able to sort out the levels.

They even give a pretty diagram to show you:



The way that we normally work for broadcast is that we have our Broadcast Engineer, who is constantly able to see a Loudness Meter - so that he can be hitting targets, then the output of the desk hits a TC DB2 to smooth over any things the engineer might miss.

We have had complaints about our mobile service being too quite, so I'd love to address that, does anyone have any practical thoughts on how to actually implement these recommendations?

It will unfortunaltely need to be a "set and forget" type operation...

Simon "Smash" Ashby

I use Soundcheck on my iPhone, I think it's poorly implemented but basically a good idea. I used to use mp3gain (based on replaygain) to set levels for music on my Iriver, it works much better than soundcheck.

I have used replaygain to set the level of audio for DVD. I use a utility that allows the user to add extra gain (above the replay gain standard) to audio. I run it over live video soundtracks, with an additional 6db, to put stuff on youtube.

Replaygain is based on some cinema standard apparently. On X reference system a replaygain parsed file will play at 89db. Whatever the detail, I've used it for years to get even loudness in all the live music video files I process.

http://www.replaygain.org

From above link:

"Reference level

The audio industry does not have a standard for playback system calibration, but in the movie industry a calibration standard has been defined by the Society of Motion Picture and Television Engineers (SMPTE).[6] The standard states that a single channel pink noise signal with an RMS level of -20 dB relative to a full-scale sinusoid[7] should be reproduced at 83 dB SPL.[8]

ReplayGain adapts the SMPTE calibration concept for music playback. Under ReplayGain, audio is played so that its loudness, as measured using the procedures described in Loudness measurement above, matches the loudness of a pink noise signal with an RMS level of -14 dB relative to a full-scale sinusoid,[9] also measured using the procedures described above.

In ReplayGain implementations, the reference level is described in terms of the SMPTE SPL playback level. By the SMPTE definition, the 83 dB SPL reference corresponds to -20FS dB system headroom. The -14 dB headroom used by ReplayGain therefore corresponds to an 89 dB SPL playback level on a SMPTE calibrated system and so is said to be operating with an 89 dB reference level.

SMPTE cinema calibration calls for a single channel of pink noise reproduced through a single loudspeaker. In music applications, the ideal level of the music is actually the loudness when both speakers are in use. So, ReplayGain is calibrated to two channels of pink noise.[10] "