Optional chunk types containing the looping information for the ADPCM file. You don't need to byte swap the contents of the data chunk. When you use ADPCM in XAudio2, you need to read the contents of the data chunk into a buffer, and pass it to a source voice as the pAudioData member of an XAUDIO2_BUFFER structure.
The data in this chunk corresponds to a ADPCMWAVEFORMAT structure.Ĭontains the encoded ADPCM audio data. Standard RIFF chunk containing a file type with the value WAVE in the first four bytes of its data section and the other chunks in the file in the remainder of its data section.Ĭontains the format header for the ADPCM file. ADPCM File StructureĪn ADPCM file is a standard RIFF file with the following chunk types. If you use the wave exclusively in non-looping mode, the sample block alignment restriction does not apply. Remove it from the looping play events, and re-apply compression. You cannot compress a wave used in any looping play events. If you try to apply compression to a non-aligned wave, you will get an error or a warning depending on whether the wave is used in any looping play events. The value of the SamplesPerBlock parameter affects the resolution with which you can align wave data and loop points. The ADPCM decoder generates silence for the remainder of this partial block, which keeps the wave from looping seamlessly. In general, modifying the SamplesPerBlock value results in these tradeoffs: If SamplesPerBlock.īecause ADPCM uses sample blocks that are aligned one after the other, a wave compressed with ADPCM may have an unfinished, partial block at its end. Larger blocks allow better compression, which results in smaller file sizes, but at the expense of sound quality and resolution for aligning loop points.
The smallest block size is 32 samples, and the highest is 512 samples. The size of the blocks is measured in samples. For an example of loading and playing a sound in XAudio2, see How to: Play a Sound with XAudio2.ĪDPCM compression works by separating the waveform into blocks, and predicting the variation of the waveform samples within each block. In order to use ADPCM encoded data in XAudio2, you need to initialize a ADPCMWAVEFORMAT structure with ADPCM specific values, and pass it as an argument to IXAudio2::CreateSourceVoice when you create a source voice.
#MICROSOFT ADPCM AUDIO CODEC WINDOWS 7 SOFTWARE#
Software decoding of ADPCM is supported in XAudio2. In order to encode audio files as ADPCM for use with XAudio2, use the AdpcmEncode command-line tool. Currently, ADPCM compression is only available for Windows, including XNA Game Studio Express for Windows deployments.Īudio data is encoded to ADPCM using the AdpcmEncode command-line tool.
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