see http://contributing.appspot.com/deadbeef
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You need to make GDB backtrace.
short answer:
upgrade to deadbeef-0.5.1, make sure that SRC (resampler) plugin has been built, then quit the player, and delete the file ~/.config/deadbeef/dspconfig.
after player restart, it will auto-configure itself to emulate 0.4.4 behaviour.
long answer:
by default, version 0.5 uses resampler provided by ALSA (or PulseAudio, or OSS - depending on chosen output plugin), and ALSA is not always capable to resample. and, in some cases, ALSA resampling cannot be used at all, depending on which output device is selected in Preferences.
version 0.4.4 (and below) resampled output using libsamplerate by default, without using ALSA resampling -- that's why it always worked.
To use libsamplerate resampling, go to Edit -> Preferences -> DSP, add Resampler plugin, and configure it to any samplerate that your output supports.
SRC plugin from 0.5.1 can automatically configure samplerate to match output plugin.
In most cases - yes, I can. But that doesn't mean I ever will, and I won't give any promises.
Information is here