I need a small, self-contained Android app that can load several MP3 files—either picked from the device or pulled from common cloud drives—and mix them into a single playback stream. Core functionality must include: blending multiple tracks, real-time volume adjustment, and the ability to drop short “announcement” clips at fixed intervals or only at the end. While an announcement is playing the main track should continue underneath it, with separate gain sliders so the voice-over can duck or sit on top of the music cleanly. A straightforward interface is fine: once the user imports the audio, simple buttons and sliders can control start time, interval timing, and individual track volumes. I’m less concerned with flashy UI widgets than with smooth, gap-free playback and low CPU use on typical mid-range devices. Please deliver: • Android Studio project (Java or Kotlin) with clear, in-line comments • Signed debug APK for immediate testing • Brief README covering build steps and any third-party libraries used Acceptance will be based on glitch-free mixing, correct timing of announcements, and independent volume control that behaves the same across at least Android 9–14.