You are previewing HTML5: Up and Running.

HTML5: Up and Running

Cover of HTML5: Up and Running by Mark Pilgrim Published by O'Reilly Media, Inc.
  1. HTML5: Up and Running
    1. SPECIAL OFFER: Upgrade this ebook with O’Reilly
    2. Preface
      1. Diving In
      2. Conventions Used in This Book
      3. Using Code Examples
      4. A Note on the Editions of This Book
      5. Safari® Books Online
      6. How to Contact Us
    3. 1. How Did We Get Here?
      1. Diving In
      2. MIME Types
      3. A Long Digression into How Standards Are Made
      4. An Unbroken Line
      5. A Timeline of HTML Development from 1997 to 2004
      6. Everything You Know About XHTML Is Wrong
      7. A Competing Vision
      8. What Working Group?
      9. Back to the W3C
      10. Postscript
      11. Further Reading
    4. 2. Detecting HTML5 Features
      1. Diving In
      2. Detection Techniques
      3. Modernizr: An HTML5 Detection Library
      4. Canvas
      5. Canvas Text
      6. Video
      7. Video Formats
      8. Local Storage
      9. Web Workers
      10. Offline Web Applications
      11. Geolocation
      12. Input Types
      13. Placeholder Text
      14. Form Autofocus
      15. Microdata
      16. Further Reading
    5. 3. What Does It All Mean?
      1. Diving In
      2. The Doctype
      3. The Root Element
      4. The <head> Element
      5. New Semantic Elements in HTML5
      6. A Long Digression into How Browsers Handle Unknown Elements
      7. Headers
      8. Articles
      9. Dates and Times
      10. Navigation
      11. Footers
      12. Further Reading
    6. 4. Let’s Call It a Draw(ing Surface)
      1. Diving In
      2. Simple Shapes
      3. Canvas Coordinates
      4. Paths
      5. Text
      6. Gradients
      7. Images
      8. What About IE?
      9. A Complete Example
      10. Further Reading
    7. 5. Video on the Web
      1. Diving In
      2. Video Containers
      3. Video Codecs
      4. Audio Codecs
      5. What Works on the Web
      6. Licensing Issues with H.264 Video
      7. Encoding Ogg Video with Firefogg
      8. Batch Encoding Ogg Video with ffmpeg2theora
      9. Encoding H.264 Video with HandBrake
      10. Batch Encoding H.264 Video with HandBrake
      11. Encoding WebM Video with ffmpeg
      12. At Last, the Markup
      13. What About IE?
      14. A Complete Example
      15. Further Reading
    8. 6. You Are Here (And So Is Everybody Else)
      1. Diving In
      2. The Geolocation API
      3. Show Me the Code
      4. Handling Errors
      5. Choices! I Demand Choices!
      6. What About IE?
      7. geo.js to the Rescue
      8. A Complete Example
      9. Further Reading
    9. 7. The Past, Present, and Future of Local Storage for Web Applications
      1. Diving In
      2. A Brief History of Local Storage Hacks Before HTML5
      3. Introducing HTML5 Storage
      4. Using HTML5 Storage
      5. HTML5 Storage in Action
      6. Beyond Named Key/Value Pairs: Competing Visions
      7. Further Reading
    10. 8. Let’s Take This Offline
      1. Diving In
      2. The Cache Manifest
      3. The Flow of Events
      4. The Fine Art of Debugging, a.k.a. “Kill Me! Kill Me Now!”
      5. Let’s Build One!
      6. Further Reading
    11. 9. A Form of Madness
      1. Diving In
      2. Placeholder Text
      3. Autofocus Fields
      4. Email Addresses
      5. Web Addresses
      6. Numbers As Spinboxes
      7. Numbers As Sliders
      8. Date Pickers
      9. Search Boxes
      10. Color Pickers
      11. And One More Thing...
      12. Further Reading
    12. 10. “Distributed,” “Extensibility,” and Other Fancy Words
      1. Diving In
      2. What Is Microdata?
      3. The Microdata Data Model
      4. Marking Up People
      5. Marking Up Organizations
      6. Marking Up Events
      7. Marking Up Reviews
      8. Further Reading
    13. A. The All-in-One Almost-Alphabetical Guide to Detecting Everything
      1. List of Elements
      2. Further Reading
    14. Index
    15. About the Author
    16. Colophon
    17. SPECIAL OFFER: Upgrade this ebook with O’Reilly

Audio Codecs

Unless you’re going to stick to films made before 1927 or so, you’re going to want an audio track in your video. Like video codecs, audio codecs are encoding algorithms, in this case used for audio streams. As with video codecs, there are lossy and lossless audio codecs. And like lossless video, lossless audio is really too big to put on the Web, so I’ll concentrate on lossy audio codecs.

Actually, we can narrow the focus even further, because there are different categories of lossy audio codecs. Audio is used in many places where video is not (telephony, for example), and there is an entire category of audio codecs optimized for encoding speech. You wouldn’t rip a music CD with these codecs, because the result would sound like a four-year-old singing into a speakerphone. But you would use them in an Asterisk PBX, because bandwidth is precious, and these codecs can compress human speech into a fraction of the size of general-purpose codecs. However, due to lack of support in both native browsers and third-party plug-ins, speech-optimized audio codecs never really took off on the Web. So I’ll concentrate on general-purpose lossy audio codecs.

As I mentioned in Video Codecs, when you “watch a video,” your computer is doing several things at once:

  1. Interpreting the container format

  2. Decoding the video stream

  3. Decoding the audio stream and sending the sound to your speakers

The audio codec specifies how to do #3—decoding the audio stream and turning it into digital waveforms that ...

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