Did you know that it was possible to use the HTC One camera application on the HTC One A9? We have been able to extract the files the package includes HTC 10 Camera, Gallery, Zoe. Just keep in mind that the stock camera is by far better, but this can be a interesting thing to try out if you are running an AOSP or CM based Custom ROM. This hack is working on almost all android phones as well.
To install, it download it from the following link and place it on the storage of your HTC One A9. Then, boot into One A9’s custom recovery, browse for the downloaded file and flash it from there.
As said earlier, it is working just fine, even on cyanogens mod 13 ROMs for One A9 but we still recommend using the stock camera when taking serious pictures. Yes, we love the fact that you can take some really nice slow motion videos with the HTC 10 camera app but the image quality is still the best with the stock camera of HTC One A9.