====== jPC Audio Features ======

The jPC has an internal mono speaker and a stereo audio 1/8" jack for external speakers.  

===== Adjusting Volume =====

Use the [[https://manpages.debian.org/stable/alsa-utils/alsamixer.1.en.html|alsamixer]] utility to adjust audio levels of each.  The external speaker output is labeled "Headphone" and the internal speaker output is labeled "Line Out".

{{ https://downloads.comfiletech.com/jPC/videos/jpc-alsamixer.mp4?908x572 }}

===== Playing Audio from a Terminal Console =====

To test the left and right channels individually:
  * Left channel: <code>ffplay -autoexit /usr/share/sounds/alsa/Front_Left.wav -af "pan=stereo|c0=0*c0|c1=c0"</code>
  * Right channel: <code>ffplay -autoexit /usr/share/sounds/alsa/Front_Right.wav -af "pan=stereo|c0=c0|c1=0*c0"</code>

===== Playing Audio in a .NET Program =====

To play audio in a .NET program, consider using [[https://www.nuget.org/packages/Alsa.Net|Alsa.NET]]
<code C#>
#:package Alsa.Net@1.0.10

using System;
using Alsa.Net;
using System.Reflection;
using System.Runtime.InteropServices;

class Program
{
    // This is needed to map the library name that Alsa.NET searches for to the exact library file
    // on the jPC.
    static IntPtr DllImportResolver(string libraryName, Assembly assembly, DllImportSearchPath? searchPath)
    {
        if (libraryName == "libasound")
        {
            return NativeLibrary.Load("/usr/lib/aarch64-linux-gnu/libasound.so.2");
        }

        // Otherwise, fallback to default import resolver.
        return IntPtr.Zero;
    }

    static void Main(string[] args)
    {
        NativeLibrary.SetDllImportResolver(typeof(SoundDeviceSettings).Assembly, DllImportResolver);

        var soundDeviceSettings = new SoundDeviceSettings();
        using var alsaDevice = AlsaDeviceBuilder.Create(soundDeviceSettings);

        alsaDevice.Play("/usr/share/sounds/alsa/Front_Center.wav");
    }
}
</code>