NXPowerLite performs a pre-compression check on video files to ensure that the file is a good candidate for compression with the built-in optimization settings. It was implemented after our testing showed that in some cases NXPowerLite would try to optimize files and it would take a long time for very little compression or the file would end up larger than the original file, meaning it could not be saved. In summary, it was designed to ensure that NXPowerLite can quickly skip files that it will not be able to compress very well.
In order to do this is uses some properties of the Video Track and calculates the amount of data allocated to each pixel in the video (Bits/(Pixel*Frame). We have then set a Compression Metric for this value below which files will be marked as Already Optimal and skipped.
Compression Metric for Video files
For video files with the Baseline Format Profile the minimum threshold is 0.21
For video files with any other Format Profile the threshold is 0.07
Investigate why your files are flagged as Already Optimal
1. Install MediaInfo tool on your system. (Free utility available on multiple platforms)
Please note that this is a 3rd party tool so please use at your own discretion
2. Right-click the video file and select MediaInfo
3. Scroll down to expand the Video section
4. Determine the Format Profile and Bits/(Pixel*Frame)
5. Compare with the Compression Metric values above