Question

I have a double pointer data->mono_channel, where I would like to cast all the doubles to integers and put them in an array.

int frames = data->audio_info_save->frames;
short buffer[frames];
double* p;
int i = 0;
for (p = &(data->mono_channel)[0]; p < &(data->mono_channel)[frames]; p++) {
  buffer[i] = (int) *p;
  i++;
}

The purpose is that ALSA takes an integer array of samples, and my samples are in doubles.

if ((err = snd_pcm_writei(playback_handle, buffer, frames)) != frames) {
  fprintf(stderr, "write to audio interface failed (%s)\n", snd_strerror(err));
  exit(1);
}

So somehow I need my doubles to be casted to integers.

I don’t hear any sound. So is the casting done correctly?

Answer 1

It looks okay, it’d be easier to just:

for (i = 0; i < frames; i++) {
  buffer[i] = (int)pdata->mono_channel[i];
}

Is the data PCM encoded? That might be your problem.