LLStream.exe Plays Streaming Audio Files

ID: Q186493

The information in this article applies to:

Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 5.0

SUMMARY

LLStream.exe is a sample that contains a Visual Basic project that demonstrates how to play streaming audio files by calling several low-level functions in the Windows API. This sample helps you create a program that plays audio files continually without slowing down the operating system.

MORE INFORMATION

The following files are available for download from the Microsoft Download Center. Click the file names below to download the files:

LLstream.exe

The sample uses several low-level functions in the Windows API to work around the Multimedia Control Interface. You must be familiar with using Visual Basic to call the Windows API functions to understand how this sample works.

When you run the self-extracting executable file, the following files are expanded into the Low-Level Streaming Audio Sample Project directory:

Form1.frm (3Kb) - the main form

Module1.bas (12Kb) - the module containing the function declarations

Project1.vbp (1Kb) - the main project file

Project1.vbw (1Kb) - the project workspace

Readme.txt - overview of the sample and download information

The Multimedia Control Interface (MCI) is the one way to add multimedia capabilities to your program in Visual Basic. However, when you use the MCI to play audio files continuously, you can slow down or lock the operating system.

This sample shows how to call the appropriate functions directly to work around the limitations of the MCI. Because the sample hooks into a Windows process, you should compile this sample and run the executable file rather than running the sample from the Visual Basic design environment.

The sample uses the following functions in the Windows API:


   GlobalAlloc
   GlobalFree
   GlobalLock
   mmioAscend
   mmioClose
   mmioDescend
   mmioDescendParent
   mmioOpen
   mmioRead
   mmioReadString
   mmioSeek
   mmioStringToFOURCC
   PostWavMessage
   RtlMoveMemory
   waveOutClose
   waveOutGetDevCaps
   waveOutGetErrorText
   waveOutGetNumDevs
   waveOutGetPosition
   waveOutOpen
   waveOutPrepareHeader
   waveOutReset
   waveOutUnprepareHeader
   waveOutWrite

Additional query words:

Keywords : kbfile
Version : WINDOWS:5.0
Platform : WINDOWS
Issue type : kbinfo