{
boost::mutex::scoped_lock lm (_mutex);
_audio_stream.reset (new AudioStream (examiner->audio_frame_rate(), examiner->audio_channels ()));
AudioMapping m = _audio_stream->mapping ();
{
boost::mutex::scoped_lock lm (_mutex);
_audio_stream.reset (new AudioStream (examiner->audio_frame_rate(), examiner->audio_channels ()));
AudioMapping m = _audio_stream->mapping ();