Certain songs won't play
1. Song's format is unsupported with free version
2. Song needs the Open SL API setting
3. The song has been marked "troublesome"
4. What about M4P files? What about MP4?
1. The song's format is unsupported
What is the file format you're trying to play? To determine this, long press on the file in question and select "Edit Tag" in Rocket Player or a tag editing app. At the top of the tag editing screen, there will be its file path. At the very end it will have the format (e.g. mp3, m4a, etc). Rocket Player and other JRT Studio apps are able to play Android supported formats with the free version. The premium (paid/ads) version of Rocket Player are able to play advanced formats WMA, FLAC, and more listed here
Above, we have a .mp3 formatted song.
Above, we have a .wav formatted song.
Rocket Player Premium Unlocker (paid/ads) supports:
ALAC (Apple Lossless) files, APE (ape), Musepack (mpc), Free Lossless Audio Codec (flac), True Audio (tta), Waveform Audio File (wav), WavePack (wv) and Windows Media Audio Non-Lossless (wma) in addition to the Android supported formats.
FAQs and issues with playing in Rocket Player