更换声卡并播放MP3

Question

I want to play an MP3 on a sound card other than the default (eg I plugged in a USB headset).

I have code that works perfectly fine if I want to play a WAV file on a different sound card. But with MP3, it just fails. I am trying to write the code in C#, but for the sake of there being nothing between the app and WinAPI (eg interop), I translated it to VB6. Specifically, what fails is the call to change the sound card - mciSendCommand - and it fails with error 274 - The MCI device you are using does not support the specified command . The sequence with the MCI type operations is typically like this: Open File, Do Operations (eg change sound card, etc...), then play.

Dim cmd as String
Dim rc as Long
Dim lngDeviceID As Long
Dim parms As MCI_WAVE_SET_PARMS

cmd = "Open test.mp3 type mpegvideo alias Mp3File"
rc = mciSendString(CommandString, vbNullString, 0, 0&)  ' Open works

lngDeviceID = mciGetDeviceID("Mp3File")
parms.wOutput = 1 ' tell it to playback on the 2nd card 

rc = mciSendCommand(lngDeviceID, MCI_SET, MCI_WAVE_OUTPUT, parms) ' FAILS with 274
If (rc <> MMSYSERR_NOERROR) Then
    ' The command failed.
    MsgBox "Change card: " & GetMCIErrorString(rc)
End If

Interestingly, if I want to play a WAV file, for which I have to open it with waveaudio instead of mpegvideo (like this cmd = "Open test.mp3 type waveaudio alias WAVFile" ), everything works fine. But no matter what I tried it won't work if I try to open an MP3 file.

What am I missing? I've seen a dozen unanswered questions like this going back to 2000 - there has to be a way to play an MP3 file on a different sound card.

Answer 1

have you tried to change

cmd = "Open test.mp3 type mpegvideo alias Mp3File"

to

cmd = "Open test.mp3 type mpegvideo alias MediaFile" ?

have a look at this article on CodeProject that uses .NET and Winmm.dll to play MP3 files:

"MP3 Helper Class - http://www.codeproject.com/Articles/95000/MP3-Helper-Class"