The SM5 can use a compressed file format to reduce the file size of acoustic recordings.
Options
- None (default)
- W4V-8
- W4V-6
- W4V-4
Both acoustic channels must use the same compression setting.
With the default setting of no compression, the SM5 saves acoustic recordings in WAV format. WAV is an uncompressed audio format that is widely supported by many audio analysis and playback systems.
The SM5 can optionally apply three different levels of compression in W4V format. W4V is an open-source format for compressed audio developed by Wildlife Acoustics specifically for bioacoustics applications.
Effects of Compression on File Size and Audio Quality
As greater levels of W4V compression are applied, the file size decreases, and the level of background noise increases.
| Compression Setting | File Size | Effects on Audio |
|---|---|---|
| W4V-8 | 50% smaller than WAV | Increased noise floor, imperceptible in most circumstances |
| W4V-6 | 62.5% smaller than WAV | Increased noise floor, imperceptible in some circumstances |
| W4V-4 | 75% smaller than WAV | Increased noise floor, perceptible in most circumstances |
In many typical bioacoustics recording use cases, the surrounding environment is the most significant source of background noise. In these settings, small increases in the noise of the recording system, such as from the W4V-8 or W4V-6 settings, are insignificant compared to the environmental noise and may have no practical effect on the quality of the recorded audio.
Converting between WAV and W4V
Wildlife Acoustics' Kaleidoscope analysis software can be used to convert between WAV and W4V files for free, without a paid license. Additionally, the W4V algorithm is open-source under a GPLv3 license and may be integrated into other software tools.
W4V's increased noise floor cannot be removed by converting the file to WAV.