title: Pydub - combine split_on_silence with minimum length / file size
body: <p>I have two scripts, one of them splits audio of a certain length, the other one splits audio on every time there is a silent passage. Would it be possible to split the audio on silence, but only after a certain time passed? I would need chunks of videos split on silence which are not shorter than 5 minutes.</p>
  
  <p>Splitting script with ignores silence:</p>
  
  <pre><code>from pydub import AudioSegment
  #from pydub.utils import mediainfo
  from pydub.utils import make_chunks
  import math
  
  #lac_audio = AudioSegment.from_file("Kalimba.mp3", "mp3")
  #flac_audio.export("audio.mp3", format="mp3")
  myaudio = AudioSegment.from_file("Kalimba.mp3" , "mp3")
  channel_count = myaudio.channels    #Get channels
  sample_width = myaudio.sample_width #Get sample width
  duration_in_sec = len(myaudio) / 1000#Length of audio in sec
  sample_rate = myaudio.frame_rate
  
  print "sample_width=", sample_width 
  print "channel_count=", channel_count
  print "duration_in_sec=", duration_in_sec 
  print "frame_rate=", sample_rate
  bit_rate =16  #assumption , you can extract from mediainfo("test.wav") dynamically
  
  
  wav_file_size = (sample_rate * bit_rate * channel_count * duration_in_sec) / 8
  print "wav_file_size = ",wav_file_size
  
  
  file_split_size = 10000000  # 10Mb OR 10, 000, 000 bytes
  total_chunks =  wav_file_size // file_split_size
  
  #Get chunk size by following method #There are more than one ofcourse
  #for  duration_in_sec (X) --&amp;gt;  wav_file_size (Y)
  #So   whats duration in sec  (K) --&amp;gt; for file size of 10Mb
  #  K = X * 10Mb / Y
  
  chunk_length_in_sec = math.ceil((duration_in_sec * 10000000 ) /wav_file_size)   #in sec
  chunk_length_ms = chunk_length_in_sec * 1000
  chunks = make_chunks(myaudio, chunk_length_ms)
  
  #Export all of the individual chunks as wav files
  
  for i, chunk in enumerate(chunks):
      chunk_name = "chunk{0}.mp3".format(i)
      print "exporting", chunk_name
      chunk.export(chunk_name, format="mp3")
  </code></pre>
  
  <p>Splitting script which ignores length:</p>
  
  <pre><code>from pydub import AudioSegment
  from pydub.silence import split_on_silence
  
  sound = AudioSegment.from_mp3("my_file.mp3")
  chunks = split_on_silence(sound, 
      # must be silent for at least half a second
      min_silence_len=500,
  
      # consider it silent if quieter than -16 dBFS
      silence_thresh=-16
  
   )
  
  for i, chunk in enumerate(chunks):
      chunk.export("/path/to/ouput/dir/chunk{0}.wav".format(i), format="wav")
  </code></pre>