One of the more sophisticated music accompaniment filters on the market, the new Strum app turns any 15-second clip into a short music video--and the effect can be cute or blood-curdling, depending on the source material.

Released in December by San Francisco app maker Smule, Strum is free and requires, at minimum, iOS 6.0 running on iPhone 4, iPod touch 4, iPad 2 or iPad mini. The user interface is impeccably clean, simple and intuitive: shoot a quick video, add an audiovisual filter from 16 presets, then share through Facebook, Twitter, email or Smule's new social back-end Smule Nation.

This digital pocket bauble, which has about 1 million installs, takes some time to wrap one's head around-for example, a Strum of two adults talking in a meeting yields regret. However, a video of an infant giggling or puppy playing outside will become even more adorable with this app's assistance. Strum's algorithm finds the tonal center of a baby's giggle, and adjusts the pitch of the acoustic guitar to harmonize with the original audio.

Strum is Smule's belly flop into social video, after the 65-person company issued hit apps like Magic Piano (31 million installs), Ocarina (9.3 million) and I Am T-Pain (5.9 million). Smule's latest release contains the ability to follow and get followers, as well as dual citizenship in Smule Nation, which links about 15 million monthly active users spread out across Smule's vast array of products. And fans of the app willing to pay a little for more musical options are in luck, as Smule upsells Strum users on extra filters.