[alsa-devel] Click sound when playing "silence" buffer

[Владимир Мартьянов]

Hello! I'm completely new to ALSA and I tried to do a simply buzzer using it.

During the debug I noticed a strange behaviour: I used
SND_PCM_FORMAT_S8 format, tried to play the buffer filled with zero
bytes and I heard click sound when my program starts and end playing
the buffer. When I filled the buffer with 0x80 bytes I didn't hear any
clicks. The closer the bytes value to 0x80, the quieter the click is.

I tried snd_pcm_format_set_silence() instead of memset() and got
clicks too. Why I got them?

Does it mean what when I use some formats, the values in buffer for
zero output voltage are not 0x00?

My source code is in attachment, my sound card is Intel HDA.
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