Seems that there is a bug in the FlacReader. I added it to my DJ application, there I have a Thread that always reads in portions of 64K buffers. I get random “jumps” (like very small loops) in the audio that is coming out.
And when reading further than the amount of samples the file has, I get a small FM-like sound.
All other JUCE AudioFormatReaders work well and don’t produce any kind of artifacts.
If you want, I can send you the .EXE of my app together with the test-FLAC I use, if that helps.