You can use Automator assuming the built in encodings are adequate for your needs. Try this:
1: Open Automator (it is in your Applications folder)
2: From the choose type window, choose Application and press Choose
3: From the Library column (on left), choose Movies
4: Select Encode Media and drag and drop it in the right panel
5: Select your encoding setting. For H.264 there is 480p, 720p, 1080p, and 2160p. Choose the size you want to downsize to.
6: To protect your original content, do not check the "Delete source files after processing."
7: Save the Automator project to a convenient place like your Desktop
8: To batch convert your videos, simply select one at a time or all at once and drag and drop them on top of the your custom app. You will see the new files appearing alongside the originals with a -1 suffixed.
Hope this helps. If you are looking for other settings you can look at Compressor from Apple. However, there is a cost associate with it.
If you don't want to use Automator, this is available right in the Finder. Select a file or files and right click on it. You should see Encode Selected Video Files. Choose that and you will get an interface just like the Automate patch.
