Convolution filtering

[simoncn]

The double-speed playing sounds like a renderer issue. When you skip to another part of the song, the renderer should stop streaming (which should kill the first ffmpeg process) and then restart streaming at the new file position (which starts a new ffmpeg process with the -ss option). Both ffmpeg processes should not be running at the same time.

The gapless issue also sounds like it is caused by the renderer. Using an external streamer with RuneAudio (communicating via UPnP) is likely to be more challenging for gapless playback than having both streaming and playing handled internally by RuneAudio.

Can you try this with another control point and renderer (such as BubbleUPnP running on Android) to see whether you get the same issues?