Funny that you bring that up, because there is currently a lot of confusion along with (sadly often wrong) information floating around on the internet.
Let's start with the "death of MP3"/patent expiration of MP3 first - which can be misleading (I can agree to that). In fact, the "license program for the MP3 format" and "certain related patents" ran out. MP3 is now considered "patent free". Meaning, the format is not dead at all - it will continue to flourish. In fact, we might see more and more tools using that format, since no licenses can be "addressed" anymore, which in turn means that "everyone" can use MP3 without problem now. Which was the big debate back in the days if LAME was actually considered legal or not.
I found these articles in recent days:
https://motherboard.vice.com/en_us/arti ... s-not-dead
https://marco.org/2017/05/15/mp3-isnt-dead
And this is the official announcement by Fraunhofer
https://www.iis.fraunhofer.de/en/ff/amm ... s/mp3.html
Fraunhofer does recommend to go to AAC though. Especially since AAC is common-place in portable devices, it's been used by Apple iTunes for years, and AAC i's part of the MPEG-4 video/audio stream.
The future for Broadcast streaming however, is MPEG-H - a new format that starts to kick off end of May in South Korea. It offers up to 16 audio channels, object based surround and full control over the audio stream (with presets that can be select on the playback side, and further interacted with). This was one of the topics of the AES Convention #142 in fact.
OGG (the "evolution" of that is OPUS1) is an open source format. Both OGG and OPUS1 are mainly used by Google for Youtube now. HOWEVER... only Google Chrome plays that back natively. All other browsers fall back to the MP4 format. At least to my knowledge/tests.
FLAC is a great "Lossless" CODEC, however it's sadly not widely supported - however, more so than WAVpack (which can actually go up to 96/32, while FLAC can only go to 96/24 - both are surround capable though). Apple for example seems to refuse to incorporate it into their OS (CODEC wise), and there are not many hardware players that can actually play back that format. PC wise, and with the right apps on Android however, absolutely no problem.
So which format is ultimately the best?
If you're after Lossless encoding and wide-spread usability, then I guess it's HD-AAC. Why? This stream has both a lossy and lossless version of your audio file in one. If the playback device can't understand the HD-AAC stream, it falls back to lossy AAC. HOWEVER... creating HD-AAC is not easy (so far, I only know of Fraunhofer Pro-Codec and Wavelab 9 and up), and there are still players that can't understand the HD-AAC format (I've yet to test HTML5 players for homepages), many hosts even don't interpret the AAC format right (decoding).
But to me, it's the natural evolution of MP3. "Plain" AAC (as in lossy AAC), there are many open source encoding tools available at this point. So in the long run, I think MP4 Audio (aka AAC) is the future.
In the near future, META DATA will also be a huge topic. By that I mean that the CODECs can store values like "Loudness in LUFS". But I can't comment on that yet - I have to read myself into that topic as well, what's possible currently.
One question might pop up now - which format should we use for the Mix Challenge?
Personally I'd say, we can stick to MP3, FLAC and WAV.
If we want to use AAC, is up for debate.
