int snd_seq_drain_output_buffer(snd_seq_t *handle);
int snd_seq_drain_output_buffer
Removes all events on user-space output buffer. Unlike snd_seq_drain_output, this function doesn't remove events on output memory pool of sequencer.
Function returns zero if successful, or a negative error code.
snd_seq_drain_output, snd_seq_remove_events