Playback only: pre-buffering. The server does not start with playback before at least prebuf bytes are available in the buffer. It is recommended to set this to (uint32_t) -1, which will initialize this to the same value as tlength, whatever that may be. Initialize to 0 to enable manual start/stop control of the stream. This means that playback will not stop on underrun and playback will not start automatically. Instead pa_stream_corked() needs to be called explicitly. If you set this value to 0 you should also set PA_STREAM_START_CORKED.
Referenced by pa_stream_set_buffer_attr().