Member Avatar for funfullson

Hello dears.
I need to play a music in my projects background.
I did such below but it does not work.
what is problem please?

class PlayMusic
{
    private string cmd;
    private bool isOpen;
    [DllImport("winmm.dll")]
    private static extern long mciSendString(string strCommand,StringBuilder strReturn,int iReturnLength, IntPtr hwndCallback);

    public void Close()
        {
            cmd = "close MediaFile";
            mciSendString(cmd, null, 0, IntPtr.Zero);
            isOpen = false;
        }

    public void Open(string sFileName)
        {
            cmd = "open "+ sFileName +" type mpegvideo alias MediaFile";
            mciSendString(cmd, null, 0, IntPtr.Zero);
            isOpen = true;
        }

    public void Play(bool loop)
        {
            if (isOpen)
            {
                cmd = "play MediaFile";
                mciSendString(cmd, null, 0, IntPtr.Zero);

                if (loop)
                    cmd = " REPEAT";
                mciSendString(cmd, null, 0, IntPtr.Zero);
            }
        }
    }

my headers are :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

and my playing action is:

PlayMusic pm = new PlayMusic();
pm.Open("c:\test.mp3");
pm.Play(true);

when I do it it do nothing.I dont know what is the probleme.
Thanks if help me dears.

  • 5 Contributors
  • 4 Replies
  • 385 Views
  • 2 Years Discussion Span
  • Latest Post Latest Post by Sri Harsha

Dani AI

Generated

Two things are almost always the culprit here: the C# string you pass for the filename (backslashes become escape sequences) and the way the MCI commands are built/sent (sending REPEAT as a separate call doesn't work). 's tip about removing the explicit type often helps for MP3s, and and are right that higher-level options exist (SoundPlayer only handles WAV; Windows Media Player/NAudio are more robust for MP3).

A compact, practical pattern that fixes the common errors:

[DllImport("winmm.dll", CharSet = CharSet.Auto)]
private static extern int mciSendString(string command, StringBuilder returnValue, int returnLength, IntPtr callback);

// use a verbatim or escaped path so backslashes aren't lost
string filePath = @"C:\test.mp3";
int rc = mciSendString(string.Format("open \"{0}\" alias MediaFile", filePath), null, 0, IntPtr.Zero);

// send play + repeat in one command
if (rc == 0)
    rc = mciSendString("play MediaFile REPEAT", null, 0, IntPtr.Zero);

Always check the return code and capture an error string for diagnostics. Example helper:

[DllImport("winmm.dll")]
private static extern bool mciGetErrorString(int errorCode, StringBuilder errorText, int maxLength);

If mciSendString returns nonzero, call mciGetErrorString to get a human-readable reason.

Quick checklist (debug in this order): confirm the file exists and the path is passed correctly (use @"C:\..."), quote the filename in the open command, combine play and REPEAT into one call, check the MCI error string, and verify codecs/bitness (x86 vs x64). For more reliable, feature-rich playback (seeking, volume, formats), consider Media Player ActiveX or a maintained library such as NAudio instead of hand-rolling many MCI calls.

Recommended Answers

All 4 Replies

Member Avatar for mshauny

Why do you have to go through the whole interop thing when you can use .NET build-in features to play back audio files? you can use the windows media player object available to you for free, use the DirectX audio or even use the vlc one (although its not easy to get it working) but those are the best ones you'd wanna invest you time on instead of working with legacy code written in C from the WIN API

Member Avatar for Diamonddrake

That soundplayer class in the system.media namespace is basically an interlop class that calls this very api. There's nothing wrong with using it. The reason it doesn't work appears to be the command strings. But the link ange1ofD4rkness posted is a great code snippet and if you search the DaniWeb C# code snippet library there are at least 3 code snippets for playing sounds there.

Good luck.

Member Avatar for Sri Harsha

Change the open command to by removing the type and this works for me.

cmd = "open "+ sFileName +" alias MediaFile";
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