Identifying music as a particular song

A computerized system, comprising:

• one or more processors;
• and
• one or more computer-readable devices including instructions that, when executed by the one or more processors, cause performance of operations comprising:
• storing, by a computing device, reference song characterization data that identify a plurality of audio characteristics for each reference song in a plurality of reference songs;
• receiving, by the computing device, digital audio data that represents audio recorded by a microphone;
• converting, by the computing device, the digital audio data from time-domain format into frequency-domain format;
• using, by the computing device, the digital audio data in the frequency-domain format in a music-characterization process that outputs a collection of characterization values for the digital audio data, at least some of the characterization values representing values other than binary zeros and ones;
• converting at least a subset of the collection of characterization values for the digital audio from values that are not all limited to binary zeros and ones to values that are limited to binary zeros and ones;
• comparing, by the computing device, the converted at least a subset of the collection of characterization values for the digital audio data to a plurality of characterization values for each of the plurality of reference songs, to select a subset of multiple candidate songs from the plurality of reference songs as those reference songs that correspond to the characterization values for the digital audio data, wherein the converted at least a subset of the collection of characterization values for the digital audio data are limited to binary zeros and ones, and the plurality of characterization values for each of the plurality of reference songs are limited to binary zeros and ones;
• comparing, by the computing device, the collection of characterization values for the digital audio data to the plurality of characterization values for each reference song in the subset of multiple candidate songs, to determine that the collection of characterization values for the digital audio data are most relevant to the plurality of characterization values for the particular reference song, wherein the collection of characterization values for the digital audio data include real numbers that represent values other than binary zeros and ones, and the plurality of characterization values for each reference song in the subset of candidate songs are limited to binary zeros and ones;
• and
• outputting, by the computing device in response to determining that the collection of characterization values for the digital audio data are most relevant to the plurality of characterization values for the particular reference song, an indication of the particular reference song.