FFmpeg works on Pipe protocols, and the same functionality has been ported to ffmpy so data can be written to stdin and read from stdout. You would likely have to provide some timing constructs as well to handle synchronization and appropriate buffer managment, but I see no reason this couldn't be made to work.

ffmpy: using the pipe protocol

live audio streaming with FFmpeg on a rasberry pi

import time, sys,io
import pymedia.audio.sound as sound
import pymedia.audio.acodec as acodec
import pymedia.muxer as muxer


def voiceRecorder( secs, name ):
  f = open(name,'wb')
  secs = secs*5
  dm= muxer.Demuxer('mp3')
  snds= sound.getODevices()
  rt = 44100
  cparams= { 'id': acodec.getCodecID( 'mp3' ),
             'bitrate': 128000/4,
             'sample_rate': rt,
             'channels': 2 } 
  ac= acodec.Encoder( cparams )
  snd= sound.Input( rt, 2, sound.AFMT_S16_LE )
  snd.start()
  start_time = time.time()

  while snd.getPosition()<= secs:

   s= snd.getData()
   if s and len( s ):

     for fr in ac.encode( s ):
       f.write( fr)

    else:
      time.sleep(.25)



  snd.stop()


if __name__ == "__main__":
  if len( sys.argv )!= 3:
    print 'Usage: voice_recorder <seconds> <file_name>'
  else:
    voiceRecorder( int( sys.argv[ 1 ] ), sys.argv[ 2 ]  )