Sony A1U camera to iMovie 10.1.8?

Previous versions of iMovie ( ver's 6,8 and 9) would transcode the HDV into Apple Intermediate Codec

(AIC) upon import.

iMovie version 10 does not do this; it deals with it natively, i.e. HDV. MPEG 2.

In other words iMovie takes in a copy of what is on the tape, it does not transcode.

This is similar to importing DV tape where no transcoding takes place on import.

I am wondering if High Sierra is having problems dealing with these older formats, as there have been a few issues recently on here regarding importing DV tape.Could HDV be going the same way?

Try importing using the Record feature in QuickTime Player.

How to use QuickTime Player - Apple Support

If you select the Quality to Maximum,then this should import as Pro Res which iMovie 10 should be able to work with.

You will then need to import this into iMovie.

Unfortunately you will get one long clip, rather than the usual scene breaks that you have been used to up till now.

Secondly, unfortunately, the file size for Pro Res is much larger than HDV.( but better quality than the DV you are using)

OR if you have iMovie 6,8 or 9 you could use these to import the HDV tape and then transfer the associated AIC files

into iMovie 10 which hopefully High Sierra can cope with????

Until a fix from Apple comes along, this is all I can think of trying.

Firewire connection to the camera is first.

Converter to the type of connection your machine uses is next.