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improving music mood classification using lyrics, audio and social tags

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Table 5.1 Information of <strong>audio</strong> collections hosted in IMIRSEL<br />

Audio Sets Format<br />

Number Avg. length of<br />

of tracks tracks (second)<br />

Short description<br />

USPOP wav (stereo) 8,791 253.6 Pop <strong>music</strong> in US<br />

USCRAP wav (stereo) 3,993 243.5 Unpopular <strong>music</strong> in US<br />

American wav (stereo) 5,291 183.2 American <strong>music</strong><br />

Classical wav (stereo) 9,750 242.4 Classical <strong>music</strong><br />

Metal/Elect. wav (stereo) 290 311.8 Metal & Electronica <strong>music</strong><br />

Magnatune mp3 4,648 253.9 Music released by Magnatune<br />

The Beatles wav (stereo) 180 163.8 12 CDs of The Beatles<br />

Latin wav (stereo) 3,227 221.6 Latin <strong>music</strong><br />

Assorted Pop mp3 609 233.8 Pop <strong>music</strong> in US <strong>and</strong> Europe<br />

Some <strong>audio</strong> collections shown in Table 5.1 are not usable for this research. Electronica <strong>and</strong><br />

Classical <strong>music</strong> usually do not have <strong>lyrics</strong>. While the Latin collection has <strong>lyrics</strong> in Spanish, this<br />

research is limited to investigating <strong>lyrics</strong> in English. In addition, after these <strong>audio</strong> collections<br />

were merged into a super collection, a number of songs were found to be duplicates. In many<br />

cases, the duplicates were different recordings of the same song. For example, the song “Help!”<br />

by The Beatles appeared in two albums: one was the album “Help!” released in 1965; the other<br />

was the album “1” released in 2000. In such cases, the recording with the latest release date was<br />

chosen because its sound quality was (sometimes much) better than the older ones. After<br />

eliminating duplicates, the number of songs in each <strong>audio</strong> collection is shown in Table 5.2.<br />

As the <strong>audio</strong>-based system to be evaluated in this research, Marsyas, takes .wav files as<br />

input, the mp3 tracks were converted to .wav files <strong>using</strong> the ffmpeg program 9 . All the <strong>audio</strong><br />

tracks used in the experiments were converted into 44.1 kHz stereo format before <strong>audio</strong> features<br />

were extracted <strong>using</strong> Marsyas.<br />

9 Available at http://www.ffmpeg.org/<br />

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