Cinematoraphy How many LUFS for ideal audio loudness? Why can’t we be friends?

Thảo luận trong 'ENGLISH' bắt đầu bởi Allan Tépper, 24/3/18.

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    The recent audio loudness war reminds me of the 1975 hit song Why can’t we be friends?. As I have covered in several articles about audio loudness (which we now measure in LUFS), the community had already established -16 LUFS as standard for online stereo content, and Google had supported that consensus. However, both Amazon and Spotify have demanded slightly louder levels in their smart speakers, the Amazon Echo/Alexa and the music service which also accepts spoken word content. According to Consumer Intelligence Research Partners, Amazon’s Echo devices are shipping at a rate of three to one when compared to its nearest rival, Google Home. For content producers, it’s time to get past the denial stage and adjust our workflow to allow our listeners/viewers can get the best possible audible experience. Ahead I’ll review the new expanded list, make observations and suggestions.

    In this article

    • Reminder: What is LUFS?
    • Updated list of LUFS standards, de facto and ratified
    • Denial, panic and calm investigation
    • Acceptance and analysis
    • My recommendations and conclusions


    Above you’ll hear the 1975 hit song Why can’t we be friends? from the studio album of the same name.

    Reminder: What is LUFS?


    Per Wikipedia:


    Loudness, K-weighted, relative to full scale (LKFS) is a loudness standard designed to enable normalization of audio levels for delivery of broadcast TV and other video. Loudness units relative to full scale (LUFS) is a synonym for LKFS that was introduced in EBU R128. Loudness units (LU) is an additional unit used in EBU R128. It describes Lk without direct absolute reference and therefore describes loudness level differences.

    LKFS is standardized in ITU-R BS.1770. In March 2011, the ITU introduced a loudness gate in the second revision of the recommendation, ITU-R BS.1770-2. In August 2012, the ITU released the third revision of this recommendation ITU-R BS.1770-3. In October 2015, the ITU released the fourth revision of this recommendation ITU-R BS.1770-4. The EBU has suggested that the ITU should change the unit to LUFS, as LKFS does not comply with scientific naming conventions and is not in line with the standard set out in ISO 80000-8. Furthermore, they suggest the symbol for ‘Loudness level, k-weighted’ should be Lk, which would make Lk and LUFS equivalent when LUFS indicates the value of Lk with reference to digital full scale. LKFS and LUFS are identical in that they are both measured in absolute scale and both equal to one decibel (dB). (Source: here.)
    Updated list of LUFS standards, de facto and ratified


    Everyone I know who discusses this is now calling it LUFS. I have been calling it LUFS since I first started covering the topic in June of 2015, and in many subsequent articles. Here is the current list of relevant standards I compiled as of publication date of this article, from softest to loudest. This includes both ratified, proposed and de facto standards:

    • -24 LUFS – ATSC A85 (US TV), NPRSS & PRX
    • -23 LUFS – EU R128 broadcast
    • -19 LUFS – prior de facto for mono online, including mono podcasts (before the Amazon/Spotify challenge)
    • -18 LUFS – ReplayGain (proposed)
    • -16 LUFS – prior de facto for stereo online and stereo podcast (before the Amazon/Spotify challenge)
    • -14 LUFS – Amazon Echo/Alexa and Spotify
    Denial, panic and calm investigation


    When I first became aware of Amazon and Spotify’s challenge, my first inclination was to confirm whether they would even accept or reject material at another loudness standard.

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    This is because I know that TV stations and networks sometimes reject content that is outside its published standards, i.e. back in the analog video days, US networks would reject footage without 7.5 IRE pedestal, even though 0 (zero) IRE was the standard in Japanese NTSC. (See my Why you should use Japanese NTSC with a TriCaster 40 if you use SD cameras and NewTek’s new waveform monitor graticule… and more (illustrated above).

    Although I don’t subscribe to Spotify or own any smart speaker from Amazon (Echo/Alexa) or Google (Home), fortunately our friend and Emmy-award winning actor and voiceover talent, Memo Sauceda does have an Amazon Echo/Alexa device. I asked Memo if he could try whether he could play the first episode (and then, the only published episode) of BeyondPodcasting, my new online radio show whose slogan is: “Your online show is much more than just a podcast.”

    The good news was that Memo was indeed able to audibly request BeyondPodcasting from Alexa on his Amazon smart speaker, and it played, even though that it was published at the then de facto standard of -16 LUFS. The bad news is that Memo observed that the content of BeyondPodcasting was lower in volume than Alexa’s voice. (For those unfamiliar, Alexa is the Siri type character in Amazon’s smart speakers, as well as certain Amazon Fire tablets.) Having our show at a lower volume than the host voice is not a good user experience. In addition, even though certain platforms (including Spotify) renormalize the audio content I receive, I prefer avoiding re-encoding of a very lossy format like MP3. Having a destination platform re-encode an MP3 makes me shudder as much as having someone do a PAL conversion from an NTSC VHS tape. If such a conversion must be made, it is much better made directly from the uncompressed master. MP3 and VHS are (or were) distribution formats, not production formats. They are best kept to a single generation. (This is not to say that it is certain that Spotify won’t re-normalize content that already arrives at -14 LUFS, but at least there is hope.) I am currently more concerned about the 20.54 million Amazon/Alexa devices sold as of October 2017. That was five months ago.

    Even though my first reaction was panic and frustration, I decide that this is not a war worth fighting. I have many causes for which I fight, including the proper name of the Castilian language, the proper name of the United States, the proper name of America, the elimination of forced water fluoridation worldwide and the proper display of non-integer framerates in camera menus. However, after analysis, changing the previous de facto standard to be two LUFS louder is really not a bad thing, especially since the de facto standard was just that. At -14 LUFS, our voices will be able to compensate outside noise even better, and listeners/viewers can always lower the overall volume a bit, if required.

    Acceptance and analysis


    I then decided to publish all my new online audio-only and audio/video content at -14 LUFS rather than -16 LUFS (2 LUFS louder), and began to examine the tools I already use and to interview the few tools that don’t yet support -14 LUFS:

    • Adobe Audition CC and Premiere CC — Please standby. I’m under an NDA (Non-disclosure agreement).
    • Auphonic.com (covered in several past articles) already offers -14 LUFS among its prefixes for all of its outputs, and lists it as -14 LUFS (Alexa, Spotify) on the online service. It will be soon updating its desktop apps to include -14 LUFS too.
    • Hindenburg Journalist Pro (covered in several past articles) has responded that it fortunately will be adding -14 LUFS sometime soon to its Pro version.
    • Izotope RX 6 (which I’ll be reviewing very soon) fortunately already allows creating any custom LUFS preset in its Loudness module.
    My recommendations and conclusions


    For anything that is for stereo online (including RSS distribution via podcasts), I will now publish everything new at -14 LUFS, since it is silly to spend extra time to publish some online material at -16 LUFS and some at -14 LUFS. (Rob Walch, VP at Libsyn has also been quite vocal with his same conclusion on The Feed show.)

    For anything else (including the aforementioned ATSC for US conventional television, NPRSS & PRX, EU R128 for European conventional television, we need to create proper versions for them. I recommend you do the same, using the tools that you have. If you need to publish different versions for different venues, include the standard or target in the file name. If your tools don’t yet offer -14 LUFS, upload a lossless audio version (i.e. WAV, AIFF or FLAC) to Auphonic.com to encode the final audio. By the way, Auphonic.com will also allow you to upload video files. Auphonic.com will leave the video intact (without re-encoding it, i.e. without losing a video generation) and only re-encode the audio. I will publish articles when each new tool I choose to cover adds support for -14 LUFS, either with factory presets or via a user custom preset.

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