[FFmpeg-user] silenceremove use

[To ny]

Hello good people of the ffmpeg-users list,

Because i'm not allowed to say anything in the #ffmpeg irc channel.
Weird "cannot send to nick/channel" error message appears
and thought i'd try the mailing list.

Is there anyone who has experience with the silenceremove filter? I'm trying to remove long silences from recordings i made on my phone. The silences are actually a constant noise because of the microphone gain is set to 5.0x. (The playback meter in Audacity says the noise is around -48 to 42 dB). It is around 9 hours in duration. 1,1 GB large, signed 16 bit little endian mono 16 kHz wave file. Audacity says it's 32 bit float wave file though.

To make sure that something is removed (or almost everything) i (hopefully) set the
right silenceremove arguments to -20 db.

# ffmpeg -i '/home/tony/test/Recording_53.wav' -af silenceremove=1:0:-20dB recording53_silences_removed.wav
# Removes almost nothing. File almost as large as original.
# Runs at incredible speed with e in the speed readout.
# Done is a few minutes.

# ffmpeg -i '/home/tony/test/Recording_53.wav' -af silenceremove=0:0:0:0:0:-1:0:-20dB:0:0:1:0 recording53_silences_removed.wav
# Runs at 4.5x speed (takes long, like 1:30 hours)
# leaves file of 500 MB and 4:30 hours in duration
# still has silences of same level of several seconds, sometimes a minute.

#ffmpeg -i '/home/tony/test/Recording_53.wav' -af silenceremove=start_periods=1:start_duration=0:start_threshold=-20dB:start_silence=3:star$
# Done in 40 seconds
# leaves an empty file

Does anyone know the right set of arguments for the silenceremove filter?

Thanks a bunch.