lxMusic is my personal, home-grown audio player for MP3, AAC and WAV files on Linux/Gtk
I use it all the time to play (and slice) radio podcasts from Couleur3 and Ibiza Sonica, as well as my large music collection. At this point it's not meant to be used by anyone other than myself... although I'm mulling turning it into a consumer audio player / sequencer for iOS.
Recorded on a puny Dell XPS-13 ultraslim laptop, 32-bit floats @ 44.1 kHz w/ 5 ms latency, post-downsampled to 22050 Hz for the screencast, over a hackish D/A->A/D null-loop USB 1 Roland interface. There's a screencast-related a/v shift; less noticeable on the mp4 than ogv/webm.
Differentiators
staggered audio decoder, mipmap computation CPU threads
WAV mipmaps are GPU-resident, rendered off-CPU
4096x zoom whose levels are computed at load-time in own thread, use 32mb of VRAM
wave mip-maps with custom, lossless encoding using OpenGL shaders
each mipmap entry uses 2 bytes, one for the volume maxima (outer shell) and another for the average (body)
zoomed & global WAV views rendered in real-time at 60 frames/second
beatgrid rendered as backdrop, with emphasis on down beat
combo of cairo- and OpenGL-based UI widgets; some live, others cached
Audio Engine
5 millisecond audio latency with real-time gain & any mixing
real-time time-stretching including during loops
beat-synched loops with dynamic length
fully-freeform, non-linear beat grid, initially computed from track metadata
