Convert AVCHD to iMovie, 10 times larger

Question

hi, my iMac was bought 1 year ago. Recently I got a Sony HD camcorder came with a 16GB memory stick pro. I plug the camcorder to iMac and converted the video clips to iMovie with no issue. However, when i opened the Finder and surprisingly found that the clips which exists as quick time movie files are more than 123GB! Have i done anything wrong?

Answer 1

but from 16GB to 123GB is a bit too much, isn't it? Also when i read from iMovie's help menu, it says that it needs 40GB to record 1 hr HD movie.
Not really. Depending on the numbers used, an HD file typically contains 6.5 to 9 times as much information as an SD version of the same video. As Appleman stated, AVCHD is highly compressed, typically having a data rate in the 100-120 Mbps range but wrapped in an MPEG container so as to reduced the required bandwidth to a measure comparable to that of SD files much less highly compressed.
If there anyway that i can reduced the size? ie, only copy the files from camcorder directly instead of importing them from iMovie Would that help?
Sure, you could copy the files to your hard drive or even use "Archive" option to move the files to you hard drive. This would take up much less space on your hard drive. But in the latter case the files could not be edited until you imported them into iMovie '09 which would, of course, turn them into AIC/AIFF files the same as if you had directly imported them into the application. In the former case, the files would not editable in iMovie '09 unless or until you manually convert them to an "edit" compatible compression format. But in this case you have the option of choosing what compression format and settings to use. You could, for instance, turn them into Motion JPEG or Photo-JPEG files for editing which would produce files smaller than AIC files. (SD files would be roughly half the size of AIC versions but I have never run any tests on HD files to see what king of ratio or quality you might end up with.) On the other hand, if you use a codec like H.264/AAC which allows you to set the target data rate limit, setting it low will make very small files of poor quality, moderate files of fair quality, or larger files of reasonable quality -- but the choice is entirely yours. Basically, the lower the data rate, the smaller the file and the poorer the quality. If you are importing at "full" resolution, then switching to 960x540 would also greatly reduce your editing files. Once again, the choice is yours. You must determine if file dimensions/resolution, file quality, or file storage space is most important to your work flow.