With a couple of mp3s, alsasink outputs silence at some point in the file (and 
somtimes recovers after 5-15 seconds, sometimes not), with the pipeline 
keeping running. 
 
   gst-launch-0.8 --gst-debug-level=3 filesrc location=sync-problem.mp3 ! 
typefind ! spider ! alsasink 
 
 
Right at beginning of the file: 
 
 
INFO  (1086019833:509236)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019833:509392)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019833:509445)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019833:509487)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019833:513002)            alsa(24196) 
gstalsasink.c(438):gst_alsa_sink_loop:<alsasink0> Skipping 1152 samples to 
resync (complete buffer): sample 246309 expected, but got 234823 
INFO  (1086019833:513054)            alsa(24196) 
gstalsasink.c(438):gst_alsa_sink_loop:<alsasink0> Skipping 1152 samples to 
resync (complete buffer): sample 246309 expected, but got 235975 
INFO  (1086019833:513098)            alsa(24196) 
gstalsasink.c(438):gst_alsa_sink_loop:<alsasink0> Skipping 1152 samples to 
resync (complete buffer): sample 246309 expected, but got 237127 
INFO  (1086019833:513142)            alsa(24196) 
gstalsasink.c(438):gst_alsa_sink_loop:<alsasink0> Skipping 1152 samples to 
resync (complete buffer): sample 246309 expected, but got 238279 
INFO  (1086019833:513185)            alsa(24196) 
gstalsasink.c(438):gst_alsa_sink_loop:<alsasink0> Skipping 1152 samples to 
resync (complete buffer): sample 246309 expected, but got 239431 
INFO  (1086019833:513248)            alsa(24196) 
gstalsasink.c(438):gst_alsa_sink_loop:<alsasink0> Skipping 1152 samples to 
resync (complete buffer): sample 246309 expected, but got 240583 
INFO  (1086019833:517834)            alsa(24196) 
gstalsasink.c(438):gst_alsa_sink_loop:<alsasink0> Skipping 1152 samples to 
resync (complete buffer): sample 246309 expected, but got 241735 
 
Then it plays fine for thirty-something seconds, and then starts outputting 
silence for a couple of seconds, printing this: 
 
INFO  (1086019861:002230)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:002348)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:005462)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:006101)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:006347)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:007102)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:007532)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:007773)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:008036)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:008351)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:008600)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:008837)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:009385)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:009638)             mad(24196) gstmad.c(1275):gst_mad_chain: 
recoverable lost sync error 
INFO  (1086019861:012735)            alsa(24196) 
gstalsasink.c(419):gst_alsa_sink_loop:<alsasink0> Allocating 524288 bytes 
(131072 samples) now to resync: sample 1462821 expected, but got 2011234 
INFO  (1086019863:971732)            alsa(24196) 
gstalsasink.c(419):gst_alsa_sink_loop:<alsasink0> Allocating 524288 bytes 
(131072 samples) now to resync: sample 1593893 expected, but got 2011234 
INFO  (1086019866:944717)            alsa(24196) 
gstalsasink.c(419):gst_alsa_sink_loop:<alsasink0> Allocating 524288 bytes 
(131072 samples) now to resync: sample 1724965 expected, but got 2011234 
INFO  (1086019869:915744)            alsa(24196) 
gstalsasink.c(419):gst_alsa_sink_loop:<alsasink0> Allocating 524288 bytes 
(131072 samples) now to resync: sample 1856037 expected, but got 2011234 
 
Then it plays fine again. 
 
With osssink, artsdsink, and nassink, a small glitch is audible at the 
'problem spot', but the file keeps playing fine (osssink outputs similar sync 
messages, but doesn't output silence). 
 
I'll put the file online somewhere in a sec. 
 
Cheers 
 -Tim