In a recent issue of Macworld I discussed optimizing videos for playback on an iPod connected to a television. This article prompted a question from someone sitting in the iPod Supersession I presented at the recent MacLive conference.
This someone asked if you could reduce the file and frame size of a ripped video by using HandBrake’s cropping controls to cut out parts of the video. At the time I didn’t have a comprehensive enough understanding of HandBrake’s cropping capabilities to offer more than a “Hmm” in response. I know more now and would like to share the answer with him and you.
Though I commend the aforementioned The iPod on TV article to you, here’s the gist: The 5G iPod won’t take just any old video you throw at it. The video must be encoded as an MPEG-4 or H.264 file, not exceed particular average bit rates, and must not contain more than a set number of pixels. Essentially the questioner was asking if the black bars included with some videos counted as pixels and whether cropping out those black bars would free up more pixels that could be devoted to a larger frame size (and thus a better looking movie).
The answer is: Yes, but it may be unnecessary .
HandBrake is smart and, by default, it automatically crops out a movie’s black bars. Normally you then reduce the frame size in order to create a movie with an a number of pixels acceptable to an iPod (or more precisely, as you can read in the referenced article, an acceptable number of macroblocks ).
However, you can also do this with HandBrake’s crop controls if you’re willing to lose some of the video.
If you insert a typical widescreen DVD into your Mac, launch HandBrake, and then click the Picture Settings button you’ll discover that HandBrake automatically crops the top and bottom portion of the movie by 58 and 62 pixels respectively to cut out the black bars. The Width and Height settings should come in at around 720 by 304 with the Keep Aspect Ration option enabled.
If you enable the Custom option in the Crop portion of the window and increase any of the crop settings (top, bottom, right, left), you’ll find that the Size figures change. If I crop 10 pixels from either side, for instance, the size of the frame changes to 704x304. I’ve just dropped a mess of pixels, which could conceivably allow me to fit the movie on my iPod, but I’ve also lost the left and right edges of the picture.
Frankly, I’m not sure it’s worth the trouble. I’d rather keep every bit of video the movie has to offer and muck with the size controls in order to create an iPod-compatible file. You may have a different view. If so, feel free to explore HandBrake’s crop settings.