Putting Sound and Video into Web Pages
QuickTime and AVI Compression Codecs
The term codec is the refers to a compression/decompression componet of
QuickTime.
Raw or None (60 meg - the hard disk police are going to get me
on this one)
- No compress is applied, files are HUGE!.
- Allows for the maximum frame capture, with compression being added later.
- Used to compress and playback animation clips.
- Compression is done frame by frame using RLE (Run Length Encoding), basically it goes to
the first pixel, records its colour, then counts the number of same coloured pixels until
it encounters a change in colour, at which point it starts over.
- For example: (yellow)(yellow)(red)(red)(red)(red)(blue)(blue)(blue) would become
2 (yellow),4 (red), 3 (blue)
- Provides lossless compression
- Works best for drawn or rendered still images.
Graphics (SMC)
- Similar to the Animation or RLE compression, but operates on blocks of pixels in a
frame.
- Works best with 8 bit graphics.
- Called SMC after the developer Sean M. Callahan
- Generally for most animation clips, this will do a better compression job than the
Animation one.
- This is the "common" video compression software for QuickTime.
- Designed to compress moves for fast software decompression off CD-ROM at 320x240 pixels
in 24bit colour.
- It is very slow on the compression side, but fast on the decompression side.
JPEG
- Uses the JPEG (Joint Photographic Experts Group) standard for compression images.
- This is a lossy compressor, but can close to being a lossless at the higher quality
levels.
- "Hardwired" for 24 bit colour.
- It does not support frame differencing, every frame is compressed (and can be
uncompressed) separately. This is useful if the user is expected to step through the
movie, frame by frame.
- Although the playback can be done through software, hardware decompression is required
to match playback speeds of the CinePak (Compact Video).
Indeo Video
- Original Designed by Intel to utilize the i750 chip for both capture and playback.
- Compares to the CinePak compression in terms of speed and quality
MPEG
- Very common video standard, with good compression.
- Takes a fair amount of processing power to play back.
- Several versions/levels
Sorenson Video 1 and 2
-
The latest and advanced video compression for video and streaming.
- Supported by Quicktime
- Yields very small data files, but requires quite a bit of processor power to show.
- Sample
Summary
There are quite a number of Codecs (for example, list of Quicktime Codecs) out there, which one to use depends greatly on what you are doing, the type of video, quality needed, viewer's equipment, and the capabilities of your server.
The best is to talk to someone who is an expert in this area, and go over the various options.