c - ALSA snd_pcm_drop() is not clearing complete buffer -

i using alsa api snd_pcm_drop() clear buffers. when continue audio later snd_pcm_prepare(), can hear part of previous audio supposed cleared. happens when have high value of snd_pcm_sw_params_set_stop_threshold(). if using lower value, partial audio previous audio session wont played.

what happening here ? how clear off buffer ?

(i new alsa)

thanks

" can hear part of previous audio supposed cleared." because there still audio data left in alsa buffer, , data not big enough play.enlarge audio package when put alsa buffer may solve problem.