So, I have to find a way to mute the sound output just before the audio stream is closed. The best way would be to find a simple command line audio player with the minimal number of code, since I don't want to view a huge codebase and potentially mess everything up. Fortunately, there's a program called ogg123, created by the awesome lads at Xiph.org Foundation¹. This is a very basic audio player, which is desirable for this project.

After grabbing a copy of vorbis-tools (which contains ogg123), we can take a look. The main sound output codes are located at ogg123/audio.c. And surely, there is a function called void free_audio_devices. All we have to do should be add some codes to mute the output before the free process actually begins.

I can do it cleanly by using the user space library for ALSA, but that means I may have to investigate a good amount of hours into learning, and I'm kinda busy. So nah, I just hacked it.

Since we already know how to use amixer to mute the command, we can just use system() function (provided by stdlib.h) to execute a shell command. It is not expandable and flexible AT ALL, but it works and it does not kill my brain cells.

So, the free_audio_devices looks like this now:

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void free_audio_devices (audio_device_t *devices)
{
  audio_device_t *current;

  system("amixer -c 0 set 'IEC958',0 mute");

  while (devices != NULL) {
    current = devices->next_device;
    free (devices);
    devices = current;
  }
}

Then we can trigger make and compile the patched code. Since I don't want to use this version globally, I did not install it.

Then the updated script should look like this:

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#!/bin/bash
while read file
do
	amixer -c 0 set 'IEC958',0 unmute
	sleep 1.1s
	/$SOMEWHERE/vorbis-tools-1.4.0/ogg123/ogg123 -d alsa --device-option dev:hw:0,1 "$file"
	sleep 1s
done <$1

Since now ogg123 is responsible to mute the output, we can save a line here.

And now it works! No more additional empty tracks, only accurate track data.