If we have to encode AVCHD for iMovie, we will need to download and install a top AVCHD to AIC Converter to help us to convert AVCHD to AIC MOV for iMovie on Mac OS X. I have successfully used the powerful Brorsoft MTS/M2TS Converter for Mac to trasnscode MTS/M2TS to MOV on Mac. It has iMovie's preset profile that which can give you the best video quality with highest setting. Below is my guide on converting Panasonic AG-AC130/AG-AC160 AVCHD to iMovie.
STEP 1: Download and install the Mac MTS/M2TS Converter for iMovie and then launch the program to add MTS/M2TS videos to it.
Tip: If you wanna join MTS/M2TS files for easier editing in, please check the "Merge into one" box. This MTS converter for Mac can also work as the best MTS/M2TS merger.
STEP 2: Click on Format > iMovie and Final Cut Express > Apple Intermediate Codec(AIC) (*.mov), the iMovie favorable format. Afterwards, set the output folder as you like.
STEP 3: Click the “Settings” icon and you’d better set the video frame rate as 30fps (while 25 fps for original 50p files), video size as 1920*1080 for Panasonic AVCHD video further editing with the best frame rate setting.
Step 4: Click the “Convert” button; this top AVCHD to AIC MOV Converter will convert Panasonic AC130/AC160 MTS to MOV for iMovie on Mac OS X immediately.
After the conversion, you can get the output for iMovie easily. Now, you can bring the converted AVCHD video to iMovie for editing on Mac freely.
Tips:
This Mac AVCHD Converter also support AVCHD transcoding for iMovie, FCE, FCP, etc of AG-3DA1, 3-MOS imager AVCCAM Hand-held Camcorder AG-HMC40PJ, 3-MOS POVCAM Full HD Camera Head AG-HCK10G, Sensor AVCCAM Camcorder AG-AF100, 3-CCD Handheld AVCCAM camcorder AG-HMC150PJ, 3MOS AVCCAM HD shoulder-mount camcorder AG-HMC80PJ and more models.
Related guides:
Convert Panasonic AG-AC160 to Final Cut Pro 7
Transcode Panasonic AG-HMC40 AVCHD to ProRes for FCP
Convert Panasonic AG-HMC40 MTS to AIC for FCE
Convert Panasonic AG-AF100 AVCHD to ProRes for FCP

