int split_at( int position, bool left = true );
int join( int clip, int count = 1, int merge = 1 );
int mix( int clip, int length, Transition *transition = NULL );
+ int mix_in( int clip, int length );
+ int mix_out( int clip, int length );
int mix_add( int clip, Transition *transition );
int repeat( int clip, int count );
Producer *get_clip( int clip );