Startup Scirra, which creates tools that enable you to "unlock your inner game maker" and build games based on web standards, has warned against using MP3 audio in HTML5 games. In a blog post, Scirra web developer Thomas Gullen says the company is often asked how to make an MP3 play in a game made in its Construct 2 tool, and explains that this functionality is blocked due to MP3 licensing fees.
In previous posts, Scirra has outlined the problems with audio within HTML5 apps and games: it considers Ogg the "ideal format", but notes IE and Safari don't support it; on viewing compatibility charts, MP3 initially looks to be an ideal fall-back, due to being well known and well supported.
But Gullen warns anyone considering that path must be mindful of the conditions for doing so: "The MP3 licensing website states at [the] time of writing that an MP3 license will cost US $2,500 per game title". Although no fees are due if fewer than 5,000 copies of a title are distributed, Gullen notes that this is not exclusive of web distribution and it's extremely easy to pass 5,000 plays online.
As an alternative to MP3, Gullen recommends using MPEG-4 AAC: "AAC is better than MP3 – it can produce smaller files that also sound better. Despite this, the license allows unlimited distribution in games without any fees whatsoever."