DOCUMENT:Q116293 05-DEC-1999 [win16sdk] TITLE :Direct-to-Disk Recorder with ACM PRODUCT :Microsoft Windows Software Development Kit PROD/VER:WINDOWS:3.1 OPER/SYS: KEYWORDS:kbfile kbmm kbsample kb16bitonly kbOSWin310 ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows Software Development Kit (SDK) 3.1 ------------------------------------------------------------------------------- SUMMARY ======= DDREC is a sample that shows how to use the low-level multimedia application programming interface (API) to perform direct-to-disk recording of sound using real-time audio compression from an application for Windows written in the C language. MORE INFORMATION ================ The following files are available for download from the Microsoft Download Center: Ddrec.exe For additional information about how to download Microsoft Support files, click the article number below to view the article in the Microsoft Knowledge Base: Q119591 How to Obtain Microsoft Support Files from Online Services Microsoft used the most current virus detection software available on the date of posting to scan this file for viruses. Once posted, the file is housed on secure servers that prevent any unauthorized changes to the file. The Windows MCI commands may be used to record wave audio data from within an application. However, MCI is implemented as a high-level interface. This implementation does not provide extensive control over the recording process, and does not provide easy access to the recorded data. For more control over data access and the recording process, the low-level multimedia API may be used. If you know ahead of time how much memory will be required for the entire recording, and you know that the required amount is available, you may use a simple one-shot recording procedure (ie: memory allocate, open device, record, close device). In the wave audio recording world, huge memory requirements are common and this process may not be applicable. If, however, you do not know the total recording, and/or you want to keep memory requirements to a minimum, a direct-to-disk process may be desirable. This is also known as a double buffer approach, which repeats the process of writing one filled buffer to a disk file while recording another. DDREC uses two buffers of approximately 32K each that are locally allocated at program startup. When the record process is initiated, the wave buffers are added to the input queue and recording begins. When the first buffer is filled, it is written to a temporary file while the second buffer is filled. After the buffer is written the buffer is queued to for wave audio input again. This procedure is repeated for each buffer until the user stops the recording. DDREC shows how to use these same two buffers for playing the audio as well as recording using a similar double buffer approach. It also uses the multimedia input/output (mmio*) procedures for reading and saving the wave data in a .WAV format RIFF file. DDREC also implements the WAVEFORMATEX structure for handling other wave formats besides PCM. It handles compressed formats automatically using function calls to the Audio Compression Manager (ACM). Additional query words: softlib DDREC.EXE acmFormatChoose waveInOpen waveInPrepareHeader waveInStart waveInAddBuffer waveOutOpen waveOutPrepareHeader waveOutWrite ====================================================================== Keywords : kbfile kbmm kbsample kb16bitonly kbOSWin310 Technology : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310 Version : WINDOWS:3.1 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 1999.