That is some good news; but it hurt my brain initially just to get an aac stream to add to my mp3 one and then I got caught up in all the confusion about stream types/containers/extensions.....
what does annoy me is 99% of the time the issues are caused by legal arguments over patents rather even the cheapest smartphone being unable to decode these formats (a telephone has to do more heavy work when its operating with GSM or G711A codec!) and it takes very long for them to be solved as so many competing companies are involved.
MP3 is more restricted than AAC. The licensing is a nightmare due to too many patents claims and lawsuits. It appears you need a license to broadcast in MP3.
Are there fees for using AAC? No. License fees are due on the
sale of encoders and/or decoders only. There are no patent license fees due on the distribution of bit-stream encoded in AAC, whether such bit-streams are broadcast, streamed over a network, or provided on physical media. AAC can be raw with an .AAC extension, encapsulated in a container such as .MP4 (standard practice), also in a MKV/.MKA container, and encapsulated in .M4A (the M4A container is identical to the .MP4 container, it was Apple's idea to come up with these file extensions to distinguish between audio only files (.M4A) and video files (.M4V). Technically, .M4A and .M4V are not standardized containers. Finally it can also be encapsulated in the .3GP container which is rare now a days. Theoretically it is possible in insert AAC in to a .AVI container, but it's not recommended.
OGG is wide open and a free codec like .OPUS, so you will have no problem using it for broadcasting. However, since .OPUS succeeds .OGG, and is a better codec, we might as well use it.
I hope that helps. Personally, I believe all stations should broadcast in AAC or Opus, but still broadcast at 128bps for their best quality. I think 128bps AAC = 160bps MP3, and 128bps Opus = 192bps MP3.
Lastly, if your trying to put both MP3 and AAC in one container, try using MKV/MKA. A MP4 container might work; however, it may not allow MP3 (I've never tried it). When I encode a movie from DVD, I almost always us a MP4 container. If a particular movie has a main Dolby Digital 5.1 (AC3) track, and director's comments in a 2.0 AC3 track, I will leave the AC3 5.1 alone but encode the AC3 2.0 to AAC 2.0. Using AAC @ 96kbps instead of AC3 @ 192kbps it will take half the bandwidth which will make the movie file size smaller which gives me more room on my hard drive.