This occurs using a few apks that make use of the camera (e.g., zxing, opencv). It displays a glitched image in the preview but it is still a function of what the camera se
30 FPS preview is pretty high. If you want to save some battery and CPU, consider the slowest supported FPS to be sufficient:
List supportedPreviewFpsRanges = parameters.getSupportedPreviewFpsRange();
int[] minimumPreviewFpsRange = supportedPreviewFpsRanges.get(0);
parameters.setPreviewFpsRange(minimumPreviewFpsRange[0], minimumPreviewFpsRange[1]);