Tvheadend

Trying to compile (actually ideally 4.0 branch rather than Master) - but both have this same problem.

The following error messages break the make.

...
CC src/descrambler/dvbcam.o
CC src/descrambler/ffdecsa/ffdecsa_interface.o
CC src/descrambler/ffdecsa/ffdecsa_int.o
CC src/descrambler/ffdecsa/ffdecsa_mmx.o
CC src/descrambler/ffdecsa/ffdecsa_sse2.o
CC src/descrambler/libaesdec/libaesdec.o
CC src/dbus.o
CC build.o
CC timestamp.o
CC tvheadend
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `get_delay':
(.text+0x24): undefined reference to `soxr_delay'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `flush':
(.text+0x70): undefined reference to `soxr_process'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `process':
(.text+0xa7): undefined reference to `soxr_set_num_channels'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `process':
(.text+0xb2): undefined reference to `soxr_set_error'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `process':
(.text+0xfe): undefined reference to `soxr_process'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `destroy':
(.text+0x138): undefined reference to `soxr_delete'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `create':
(.text+0x1ce): undefined reference to `soxr_io_spec'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `create':
(.text+0x205): undefined reference to `soxr_quality_spec'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `create':
(.text+0x243): undefined reference to `soxr_delete'
/opt/ffmpeg/lib/libswresample.a(soxr_resample.o): In function `create':
(.text+0x264): undefined reference to `soxr_create'
collect2: error: ld returned 1 exit status
make: *** [/home/stevemu/tvheadend/build.linux/tvheadend] Error 1

Any suggestions please?