film->set_audio_channels (6);
shared_ptr<SndfileContent> sound (new SndfileContent (film, "test/data/sine_440.wav"));
film->examine_and_add_content (sound);
film->set_audio_channels (6);
shared_ptr<SndfileContent> sound (new SndfileContent (film, "test/data/sine_440.wav"));
film->examine_and_add_content (sound);