When an EOS is encountered ( in the datastream, not an EOS event of
GStreamer), the decoder is finished with a call to
FLAC__seekable_stream_decoder_finish ( line 471 of gstflacdec.c ), and the
flag init is set to TRUE so that when a new stream is given, the decoder
would be re-inited again and the decoding could take place.

Unfortunatly the init flag only make a call to FLAC_..._init and this call
WILL fail because with the finish call, all the options/callbacks have been
resetted. ( If you look at the error code when this init happen, you'll
receive error code 'Callbacks not set' ). So to fix this problem, you can
replace the call to finish with a call to
FLAC__seekable_stream_decoder_reset, and there is no need to set the init
flag to true.

In some cases ( when going from READY to PAUSED, ... ), an init will be
performed on an already inited stream, with no consequence. The call fail
but the decoder is left untouched.