Q Many of the video files I had before upgrading to Yosemite have lost their custom icons, showing just generic QuickTime icons instead, and do not preview in QuickLook. This makes it a nightmare to navigate my stock footage. They are PNG format movies; I have updated the ProRes codecs, installed Flip4Mac, and removed Perian, to no avail. What is wrong?

A QuickTime Player will still open these movies, but in doing so transcodes them from PNG to H.264; Final Cut Pro preserves their encoding, and will import them directly.

However for QuickLook to be able to open them, it needs the appropriate plug-in, which is missing from Mavericks and later. The old PNG previewer provided with atLook (PngUncrush.qlgenerator) is currently broken, no longer maintained, and no suitable substitute is listed at the QuickLook Plugins List.

Pixa seems to have a PNG previewer, and installing it might restore PNG previews. Otherwise the only way to obtain QuickLook previews of those movie clips is to convert them to an encoding format which is supported. Whilst that may seem an onerous task, a tool such as Apple’s Compressor could do that as a batch in the background, perhaps.

Comments Choosing suitable file formats for stock footage and similar work archives is a problem. Wherever possible, stick to widely used, open standard formats. Relying on single-vendor formats is most precarious, even if they appear stable and well-supported at the time.

Note that PNG movies like these are quite different from the much more common PNG image format, which remains very well supported in QuickLook and most image apps.

Updated from the original, which was first published in MacUser volume 30 issue 05, 2014.