Loudness
farski opened this issue · comments
I suspect there's very little debate around loudness at this point
Yep, pretty much everyone has converged on -16 LUFS for stereo content, -19 LUFS for mono (which is perceptually the same). That aligns with AES TD1004.1.15-10, recommendations from people like Thomas Lund (TC Electronic) and Auphonic, and matches loudness normalization practices as performed by Apple, Spotify, and others — basically anyone focused on mobile.
There are a few outliers that may advocate for other values (like -18 http://transom.org/2016/podcasting-basics-part-5-loudness-podcasts-vs-radio/). The overwhelming majority is -16, so if we were to pick a single value I think that's the clear winner.
Maybe default to -16 but include metadata in the <item> that allows deviation? Also, the European Broadcasting Union (EBU) has a huge trove of XML metadata that could be incorporated into RSS (and Media RSS actually already includes one type of metadata in the form of <media:credit>).
Hi all!
I wrote that Transom article linked above and was a co-author on the AES mobile loudness recommendation also mentioned above.
I'd encourage you to use -18LUFS as your normalization target! neg18, as opposed to neg16, is actually much more in line with the AES recommendation. neg16 is on the outer limit of the recommendation. neg18 also gives a little more headroom, which helps improve quality.
It's also definitely worth finding a way to work in that metadata. Our European friends will appreciate that as they try to work in their hearing protection/loudness control standards.
Do let me know how I can help!
Hallo!
I am Georg from Auphonic, we worked on loudness since many years and also participated in the EBU PLOUD group which developed the EBU R128 loudness specs.
I am a fan of the AES mobile loudness recommendation as well, because it includes a range (between -16LUFS and -20LUFS) and not a single value only. A maximum true peak value of -1 dBTP is also a reasonable choice.
It might be difficult to recommend a single value as many use -16LUFS, some -18, -19 or lower (iTunes Radio, Youtube, Spotify also have their own values) - however, if it's within a range, it doesn't matter that much.
Furthermore it's a nice property, that also the often used mono loudness target of -19LUFS is inside the range of the AES recommendation. The perceived loudness of a mono signal still depends on the playback device, therefore it is necessary to add -3dB on some devices, but not on all.
(Example: If you use a stereo loudness target of -16LUFS, the mono loudness target might be -19LUFS or -16LUFS.)
BTW: thanks for the syndicated.media initiative!