Notes on various Video and Audio Coding Standards
Indeo Video 5.10
Useful for video
distributed over the Internet for computers with MMX or Pentium II processors.
This codec includes features such as a quick compression option, flexible
keyframe control, chroma keying (transparency), playback effects, and on-the-fly
cropping that reduces the data load. Also, this codec employs a progressive
download feature that adapts to different network bandwidths. Full use of these
features requires utility software available separately from Intel. This codec
is designed to work together with the Indeo Audio Software codec.
Microsoft RLE
Useful for compressing
frames that contain large areas of flat color, such as cartoon-style animation.
This codec uses a spatial 8-bit run-length encoding (RLE) compressor and is
lossless at the 100% quality setting.
Microsoft Video 1
Useful for compressing
analog video. This lossy, spatial codec supports pixel depths of 8 or 16 bits.
Intel Indeo Video R3.2
Useful for compressing
24-bit video for playback from CD-ROM discs. This codec attains higher
compression ratios, better image quality, and faster playback speeds than the
Microsoft Video 1 codec. For best results, use the Indeo Video codec on raw
source data that has not been previously compressed with a highly lossy codec.
When used with a data rate for playback, this codec produces movies that are
comparable in quality to those compressed with the Cinepak codec.
Cinepak Codec by Radius
Useful for compressing
24-bit video intended for CD-ROM discs or for downloadable Web video files. This
codec attains higher compression ratios and faster playback speeds than the
Video codec. You can set the data rate for playback; picture quality drops more
noticeably at data rates below 30 KBps. Cinepak is asymmetrical—it
decompresses quickly, but compression is slow enough to make it impractical for
editing. For best results, use Cinepak only for exporting the final version of a
video file.
(b) Audio Standards
MPEG Layer-3 Codec
Also known as mp3. This is
the third coding scheme for MPEG audio compression. MPEG Layer-3 uses perceptual
audio coding and psychoacoustic compression to remove parts of the audio signal
that are imperceptible to the human ear. The result is a compression ratio up to
12:1 without loss of audio quality. mp3 is a common format for distributing music files over the
Internet.
ACELP.net
A net-based codec using
frame-concatenation and interlacing for improved music quality. ACELP.net allows
a dual-rate bit-rate of 8.5/6.5 kbps or a fixed-rate bit-rate of 5.0 kbps.
WM-AUDIO
More fully known as
Microsoft Windows Media™ audio compression. This is the standard codec for
Microsoft Active Streaming Format which combines fast encoding with high music
quality and is optimized for Pentium II (MMX) and Pentium III (SSE/SIMD)
processors. WM-AUDIO has a wide bit-rate range from 5 kbps to 128 kbps and
offers high quality sound over the Internet even over 28.8 modems. WM-AUDIO is
considered a future replacement for MP3.
Indeo Audio Software
Useful for music and speech
distributed over the Internet. Its maximum compression ratio is 8:1. This codec
is designed to work together with the Indeo Video codec.
Microsoft G.723.1
A codec intended for use in
video conferencing. It offers acceptable voice quality, but is a poor choice for
music or sound effects. The audio quality is lower than other codecs that use
the same data rate.
L&H Codecs
Speech and music
compression algorithm developed by Lernout & Hauspie.
TrueSpeech
Useful for speech over the
Internet at low data rates.
Microsoft GSM 6.10
Useful for speech, used in
Europe for telephony.
Microsoft CCITT G.711
This codec uses µ-Law
encoding and is commonly used for digital telephony in North America and Japan.
MS-ADPCM
A Microsoft implementation
of Adaptive Differential Pulse Code Modulation (ADPCM), a common digital audio
format capable of storing CD-quality audio.
Microsoft IMA ADPCM
An implementation of ADPCM, useful for cross-platform audio for multimedia, developed by the Interactive Multimedia Association (IMA).