If a categorical input has too many levels, in your case too many genres, you can use a statistic trick
collapsing categories by thresholding. For example you can use the zip codes to map to several relevant demographic variables such as median home value, however, the levels of zip codes are too many.
Collapsing categories by thresholding method require a minimum number of cases in a level in order to create a dummy code input for that level. For example, you can do the count of each genre, if the count is below a certain value, you can collapse with another genre and give a "new name".
Another way is to collapse genres by background knowledge, if you think pop and hip-pop are similar, you can just collapse them in one genre.
Hope this helps. Reference is from the statistical learning book.