MacOS – How to see previews of old quicktime movies (old codec)

"ResEdit" was the basic utility to inspect/edit resources such as images, video, and sound in Mac OS applications and games. It runs in Mac OS or Classic environments and can be downloaded from http://www.mac.org/utilities/resedit/

"ResFork" runs on OS X 10.2 and provides similar functionality to ResEdit.

Using ResEdit or ResFork you should be able to find the codec identifier. You can then usually work from the codec identifier to a video converter. Perhaps focusing on converters from the same timeframe as the application you are working with.

If you don't have a machine that can run a Mac Classic environment, then the emulator "SheepShaver" will be useful as a debug/reverse engineer environment. SheepShaver can be downloaded from: http://sheepshaver.cebix.net/

In short, you (often) need to include the argument -pix_fmt yuv420p when using ffmpeg to generate H.264 content for Apple software/devices, and a bunch of other decoders that don't handle yuv444p.

# ffmpeg -i input.avi -pix_fmt yuv420p output.mp4

This is not mentioned in the output when using the defaults, but can be found in their Encode/H.264 guide.

It turns out that ffmpeg have chosen a default pixel format of yuv444p for libx264 encoding (under some circumstances), which is not compatible with Apple's software/hardware H.264 decoders (and perhaps not very widely compatible in general?). Unfortunately this seems unlikely to change, and there's no warning about it, so just something you have to know if using ffmpeg to make H.264 files.

As far as I can tell, if converting a video that's already using yuv420p it'll maintain that, but if converting from something a bit more exotic (e.g. images or a GIF or whatever) the pixel format must be specified for general Apple compatibility.