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Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Modern Trends in
Audio Compression
presented by
Ognen Paunovski
Andon Dragomanov
2nd International Student Spring Symposium in Contemporary Topics in IT
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Agenda
Idea Behind the Compression Lossy and Lossless Compressions Key Terms Compression Algorithms
MP3 - Format Ogg Vorbis -Format WMA – Format Format Comparison
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
In general Compression refers to a variety of ways (algorithms) to
reduce the size of a data file.
IMPORTANT Compression makes downloading quicker and lessens the amount of storage space needed on a hard drive.
The Idea Behind the Compression
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Lossy -
Lossless -
Lossy vs. Lossless Compression
After one applies lossy data compression to
a file, the file can never be recovered exactly
as it was before it was compressed.
In a lossless data compression file
after the operation of compression and
decompression will be restored to its
original format.
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Key Terms
Wave Form
Sample Bit Rate
(CBR, VBR)
Sample Rate
Code Word
Quantization
Digitalization
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Dictionary Methods
Huffman Coding
PCM Pulse Code Modulation
DPCM Differential PCM
Compression Algorithms
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Creation Process Stages: Separation into Frames Spectral Analysis “Masking” ( Psychoacoustic Models ) Processing ~ Bit Rate & Joint Stereo Compressing ( Hoffman ZIP )
CBR & VBR Most Popular
Many codec's and players
Specific Audio Formats – MP3
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Specific Audio Formats – Ogg Vorbis
Creation Process Stages: Same as those in MP3
Improvements over MP3 Designed for Streaming Connection Real Stereo ~ No Multiplexing Multi-Channel Support (more than Mono & Stereo) Bit Rate Scaling
Preferred VBR New Codec
Free Source Code One codec and few players
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Specific Audio Formats – WMA
Advanced System Format (ASF) including: Support for Meta Data Scripting Security Features
CBR & VBR (only after version 9) Industrial Support
Free Codec Few Players
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Comparison
WAV
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Comparison
MP3
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Comparison
OGG
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Comparison
WMA
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Comparison
WAV MP3 OGG WMA
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
Comparison (Cont.)
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100
200
300
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Low Quality High Quality
MP3
OGG
WMA
From a WAV File with size 3,85 MB
KB
Mar 2003 Ognen Paunovski :: Andon Dragomanov S3CTIT03
THANK YOU!
