Linux uses ALSA to play sound-basic usage __linux

1. Open the device

snd_pcm_t *handle;

 /* Open PCM device for playback. *
 rc = Snd_pcm_open (&handle, 
  "Default",
  snd_pcm_stream_playback, 0);
 The IF (RC < 0)
 {
 }

     is read-write by default block blocking mode and can be set to Non-block mode.
  snd_pcm_nonblock
   or
          snd_pcm_nonblock ()

2. Non-blocking writing (in general, the blocking way to write code is good, ALSA inside has been written, do not do it yourself retry operation)
It means to try again after a while.

  int rc = Snd_pcm_writei (handle, buf, N/4);
  printf ("Done.") rc=%d\n ", RC);
  while (RC < 0)
  {
   if (rc =-eagain)
   {
    int ms =;
    Timespec ts;
    Ts.tv_sec = ms/1000;
    Ts.tv_nsec = (ms% 1000) * 1000000;
    Nanosleep (&ts, NULL);

    rc = Snd_pcm_writei (handle, buf, N/4);
   }
  

The third parameter is the number of frame. For a S16/stereo audio, its frame = 2 * 2 = 4, which is the blockalign parameter defined by Microsoft.
If the default block mode is used, the Writei function blocks until the write succeeds. When a write succeeds, the return value RC is always equal to the number of frame passed in.

When Non-block mode, returns-eagain (-11) If the internal buffer is full. Note the eagain=11, you need to add a minus sign.

This function is either fully written or returned to-eagain, and does not occur if only one part is written.

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