Audio Drivers and Performance
Pick the Right Driver
Sound Mill allows for use of two different audio drivers:
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DirectX® driver
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Windows Media Player® (WMP) driver
Each has it's pros and cons. ONLY audio files in WAV format can utilize DirectX. All other formats (MP3, WMA, etc) will use the WMP driver regardless.
To select the audio driver for a given Sound Item, use the Play Modifier
Use Direct checkbox (Figure 1.). When checked, the DirectX driver is used. When un-checked, the WMP driver is used.
The following will help you decide which driver to use for given situations.
Recommendation -
If you don't need to use DirectX advanced features for a Sound Item , try using the WMP driver first. WMP is less processor intensive since it does not apply transformations for special effects.
Use the DirectX Driver When...
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Performance is critical - DirectX play start can be slightly faster than WMP. When a fraction of a second is critical, use DirectX.
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You need to select Output Devices - Only DirectX can selectively play on different device channels. WMP always plays on the Windows default playback device.
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3D or FX effects are needed - Only DirectX can produce these effects.
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You have a professional-quality audio card - DirectX will take advantage of advanced hardware features when available.
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Audio quality is paramont - A key thing to remember is that Wav format is a lossless format. That means that the encoding process does not reduce the quality of the sound like lossy formats can such as MP3, WMA and others. A good quality sound system will expose the sound deterioration of highly compressed, lossy formats. With the low cost of mass storage devices, larger file sizes are less of an issue.
Use the WMP Driver When...
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The audio file format is not Wav - Only Wav format can be used with DirectX drivers.
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You do not need any of the DirectX features - DirectX can be somewhat more processor intensive.
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Audio files are large - DirectX loads the entire audio file into memory (system RAM or may use soundcard memory). A ten minute music file can be 100+ Megabytes in Wav format. WMP streams the media and generally only uses about 1Meg of memory regardless of file size. So for music, use compressed formats (like MP3) with WMP drivers. We have also noted in our stress testing that extremely large files (130+ Megabyes) may fail to load by DirectX. This limit will be dependent on your computer hardware (RAM size etc.). WMP was able to load these huge files.
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The audio files are located on CD media - The WMP driver streams the audio data which means it reads a small amount of data then begins playing it while it continues to read more. The DirectX driver waits to load the entire audio file before it begins playing. For large Wav files this can create a significant delay especially when reading from a slow media like a CD-rom drive.
Figure 1. Sound Item Attributes
Sound Mill User's Guide
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