Probably unaligned memory access. Github isn't cooperating right now and it won't let me open a PR or branch, but you can apply this patch directly to the sources and see if that fixes it: [sipwise/rtpengine@ade8100](https://github.com/sipwise/rtpengine/commit/ade8100d3b10308f1ff63f8cb06fdf29...)
created the PR with the code mentioned