Courses/Design & Technique-Essential Web Design/Q2/06

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audio and video in HTML5

HMTL5 includes a standard way to embed audio and video tags, without the use of flash. It playing audio and video quite easy and opens up a lot of possibilities audio-visual interaction and manipulation.

Let's see how.


preparing your video files

Royalty Free Patented
Codec & containers Theora(video) + Vorbis(audio) > .ogv H.264 (video) + AAC or MP3 (audio) > .mp4
Browsers Firefox, Chrome, Opera Internet Explorer, Chrome, Safari

To be certain that your videos will play in all current browsers, you'll need to have videos in both .mp4 and .ogv container formats.


video codecs and containers explained

Video files such as .avi .mp4 .ogv .mkv are container formats. Like a .zip file which contains other files within it, video container formats define how to store video and audio streams within them. [1]

Each video container allow specific audio and video codecs.

A codec defines the way (the algorithm) by which a audio or video stream is encoded and decoded. [2]


video codes

H264

  • can be embedded in mp4 container
  • is patent-encumbered

Theora

  • can be embedded in any codec, but is most common in .ogv container
  • royalty-free

audio codecs

MP3

  • number of channels: 1 or 2 [3]
  • possible bitrates: 64 kbps, 128 kbps, 192 kbps
  • is patent-encumbered
  • Also known as MPEG-1 Audio Layer 3.

AAC

  • is patent-encumbered
  • number of channels: up to 48
  • Also known as Advanced Audio Coding

Vorbis

  • can be embedded in .ogg (also .mp4, .webm, .mkv) containers
  • royalty-free
  • number of channels: any


prepare your files

As said previously: To be certain that your videos will play in all current browsers, you'll need to have videos in both .mp4 and .ogv container formats. In other words you need to encode your videos into these 2 formats.

There are several solutions to do this:


tags

<video width="320" height="240" controls>
  <source src="pr6.mp4"  type="video/mp4; codecs=avc1.42E01E,mp4a.40.2">
  <source src="pr6.webm" type="video/webm; codecs=vp8,vorbis">
  <source src="pr6.ogv"  type="video/ogg; codecs=theora,vorbis">
</video>

event listeners

[4]


references

Blog on containers and codecs

AV Codes supported by video containers

notes

  1. ↑ http://diveintohtml5.info/video.html
  2. ↑ Note: a lossy audio and video compression codecs try to store the max amount of information in the smallest amount of space. One technique use to achieve this goal in video is the use of key frames instead of sequence of frames. In a second there only two or three key frames are used to create the illusion of movement, the remaining frames are filled with inbetweens, changes og pixel color. When a drastic change to the image occurs a key frame must be created.
  3. ↑ Unlike video, audio typically is in stereo, which means that it has 2 channels or streams
  4. ↑ All info on av codecs and containers in http://wiki.multimedia.cx/
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