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MediaStorm’s Guide to iPad Compression for the Web

With the advent of Apple’s new iPad, cross-platform multimedia producers have an opportunity for an additional means of distribution.

Much has been made of the iPad’s functionality, and its limitations. But there’s little actual documentation on the best way to encode for this device, particularly from Apple.

The following steps outline MediaStorm’s compressions settings for web-based iPad playback. That is, this is our best practices for creating H.264 QuickTime files for the web.

To begin, open Compressor.

(Note: If you don’t have Compressor, part of Final Cut Pro Studio, you can also use QuickTime Pro 7, available from Apple for $29.99.)

In Compressor’s Settings window (command-3), click the plus button on the right side. Choose QuickTime movie.

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A new custom setting will appear in your window named Untitled QuickTime Movie.

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Double click it to open the settings in the Inspector window.

In the Name field, rename the setting. Make sure to include the descriptors QuickTime, H.264, and the file size, and data rate, which we’ll discuss presently.

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In the Encoder tab, select the Video: Settings button.

Use the following settings:

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Compression Type:
Chose H.264.

Frame Rate:
Select the same frame rate as your QuickTime file.

(If you are unsure of your frame rate, open your movie in QuickTime Player 7. Open the Inspector window [command-I] and press play. Your frame rate, or frames per second, appears next to FPS).

Key Frames:
Select Automatic and check Frame Reordering. (Technical note: Frame Reordering creates an H.264 Main profile, distinct from the Baseline profile necessary for iPhone encodes.)

Compressor Quality:
Compressor Quality will not be available as you’ll need to restrict the Data Rate.

Data Rate:
Restrict the Data Rate to 1500kbits/sec.

The iPad will playback video up to 2.5Mbps. Increased data rate increases quality, but it also increases file size, which can make for a poor play .back experience.

Based on our testing, 1500kbs is a good compromise.

Optimized for:
Set to Download.
This is the best setting for a progressive download. The file will start playback immediately, rather than waiting for the entire file to download first.

Encoding:
Set Encoding to Best Quality.

Back in the Encoder tab of the Inspector select the Audio: Settings button.

Use the following default settings:

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Format:
Choose AAC.

Channels:
Choose Stereo (LR).

Rate:
Choose 48 kHz.

Render Settings:
Choose Best quality.

MPEG 4 AAC LC Encoder Settings:
Choose a Target Bit Rate of 320.

Return to the Encoder tab of the Inspector.

In the Streaming section choose Fast Start – Compressed Heading. This allows your file to be viewed as soon as it begins to download.

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Select the Geometry tab of the Inspector (second from right).

For 16:9 files, type 768×432 in the Frame Size windows. Choose Custom 16:9 from the pull-down window. The iPad can play back files as large as 720p (1080×720). Here too, though, increased dimensions make for larger files and take more time to download.

768×432 is a good compromise and does not look excessively degraded when viewed in full-screen iPad playback.

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For 4:3 files, type 576×432 in the Frame Size windows. Choose Custom 4:3 from the pull-down window.

For more information on how to maximize your processor speed when compressing, please check out the Qmaster section of the pdf Setting Up Final Cut Pro for Canon 5D Mark II Video on the MediaStorm submissions page. You’ll find additional information on compression there in the resources section.

Additionally, for extensive technical information on the H.264 codec, see Jan Ozer’s streaminglearningcenter.com/ and the white paper Encoding H.264 Video for Streaming and Progressive Download, which helped in the research of this article.

Have iPad encoding tricks you’d like to share? We’d love to hear from you in the comments.

Learn more about our approach to producing multimedia by purchasing MediaStorm’s Post-production Workflow. Spanning more than 200 steps, the workflow covers every phase of editing, from organizing and editing assets in Final Cut Pro 7 through backing up and archiving your project. The workflow includes exclusive access to our Aperture Workflow and our Final Cut Asset Parser. Learn more about MediaStorm’s Post-production Workflow.

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  • jamez

    You guys are awesome!!!!! Thanks a million.

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  • http://www.duckrabbit.info/blog duckrabbit

    This is very useful. It’s amazing how many people do great work and then cock it up at this stage.

    MPEGSTREAMCLIP is free andi sin my experience a better encoder then QUICKTIME.

    Also if people are looking to reduce the file size, you can reduce the quality of the audio which can account for a huge chunk of information.

  • http://mediastorm.org Eric Maierson

    I’ve never had much success with MPEGSTREAMCLIP for 264 encodes to be honest. It looks good but there always seems to be artifacts. YMMV.

    Eric

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  • http://www.brownweb.com.au/blog/ Kristopher Gucciardi

    Great post.

    Keep up the Awesome work.

    Only 6 more days until the iPad gets released in Australia ( not that Im counting )

  • Pingback: Tutorial on encoding video for the iPad | News Videographer

  • http://http//irtenkauf.com Veit

    If you want to encode for upload via iTunes rather than Web download, where size does not matter as much, the easiest way to do so is to get a copy of the free Handbrake app and then compress your movie in Handbrake with the Apple TV preset selected. For a 720p movie, it would compress it to 720p with 2500Mbps.

    This works like a charm.

  • Pingback: MediaStorm’s Guide to iPad Compression for the Web — Atlanta Photojournalist Allen Sullivan | Editorial, Documentary, Multimedia, Photographer, Videographer - Blog

  • http://www.antoinedoyen.net Antoine

    By the way, are you thinking of an iPad application for Media Storm?

    it would be awesome!

  • http://www.victrolux.com/ Victor Ingrassia

    Thanks for the clear and concise tutorial.

    Just a note… I have found that if your video’s action & motion is relatively slow and smooth, or if your video is made entirely of still images with slow dissolves between them, that one can cut your file size in half by cutting the frame rate in half (15fps or 12 fps). Obviously this compromises the quality of the motion (making it a bit more ‘steppy’ between frames. But under some circumstances the results can be quite normal feeling. It’s really a judgment call.

    Here is an example of a 10fps web version of a project:

    http://tinyurl.com/22ukcld

    The compression quality is pretty low… but that is mostly due to the non-H264 compression back in 2001 when I compressed this… as well as due to the fact that back then I was attempting to accommodate the many viewers who still had dial-up modems (!!!). Anyway, in terms of motion smoothness, it’s an illustration that you can have success using a low frame rate with slow moving video to minimize file size. Another upside of a lower frame rate is if you want you can counter balance this by raising the image quality for a less compressed look.

    ~Victor
    Victrolux Productions
    http://www.victrolux.com/

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