Courses/Design & Technique-Essential Web Design/Q2/06
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.
requirements
files
Video files such as .avi .mp4 .ogv .mkv are just container formats. Just like a ZIP file can contain any sort of file within it, video container formats only define how to store things within them, not the kinds of data are stored. [1]
Each of the container formats has a corresponding audio and video codec. A codec defines the way (the algorithm) by which a audio or video stream is encoded. [2]
- container
- medium
- audio codec
- video codec - H.264, Theora
- browser
CREATE TABLE
video codecs
H264
- can be embedded in mp4 container
- is patent-encumbered
Theora
- royalty-free
- can be embedded in any codec, but is most common in .ogv container
audio codecs
MP3
Also know as MPEG-1 Audio Layer 3.
- number of channels: 1 or 2
- possible bitrates: 64 kbps, 128 kbps, 192 kbps
- is patent-encumbered
AAC
AAC or Advanced Audio Coding
- is patent-encumbered
- number of channels: up to 48
Vorbis
can be embedded in .ogg (also .mp4, .webm, .mkv) containers
- royalty-free
- number of channels: any
audio channels
Unlike video, audio typically is in stereo, which means that it has 2 channels or streams
tags
event listeners
- ↑ http://diveintohtml5.info/video.html
- ↑ 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.
- ↑ All info on av codecs and containers in http://wiki.multimedia.cx/
