Encoding for the Apple iPad, Part 2
May 4, 2010 12:00 PM, By Jan Ozer
Last time out, I detailed how to produce videos transferred to the Apple iPad via cable, whether directly in your office or uploaded via iTunes. This time, I'll discuss how to encode files for delivering via Wi-Fi or 3G. When producing for iTunes or direct uploading, I assumed that your goal was great-looking full-screen video; if you're distributing via W-Fi or 3G, your goal could be full screen or playback within a window, but either way, your main concern is producing a video file that the iPad can play relatively smoothly while retrieving the bits either via Wi-Fi or 3G cellular.
If you're producing for Wi-Fi or 3G delivery to the iPad, your first stop should be at the "Apple Tech Note: Best Practices for Creating and Deploying HTTP Live Streaming Media for the iPhone and iPad". Note that Apple includes very specific recommendations for combined iPhone/iPad delivery, and iPad-only delivery, in both 4:3 and 16:9 aspect ratios and multiple source frame rates.
Why read any further here? A couple of reasons. First, Apple's recommendations are for adaptive streaming via the HTTP Live Streaming technique (detailed below), which you may not be using. If you're streaming only a single file, you definitely need to read on to identify the optimal configuration. Even if you are using HTTP Live Streaming, Apple doesn't detail all the encoding parameters that you'll need to produce the files, forcing you to make decisions like variable-bit-rate encoding vs. constant-bit-rate encoding on your own. If you want some help with those, you'll find the following material useful.
Let's start with a quick look at Apple's recommended encoding parameters.
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