2 nd International Student Spring Symposium in Contemporary Topics in IT . Modern Trends in Audio Compression. presented by. Ognen Paunovski Andon Dragomanov. Idea Behind the Compression Lossy and Lossless Compressions Key Terms Compression Algorithms MP3 - Format
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2nd International Student Spring Symposium in Contemporary Topics in IT Modern Trends in Audio Compression presented by Ognen Paunovski Andon Dragomanov
Idea Behind the Compression Lossy and Lossless Compressions Key Terms Compression Algorithms MP3 - Format Ogg Vorbis -Format WMA – Format Format Comparison Agenda
In general Compression refers to a variety of ways (algorithms) to reduce the size of a data file. The Idea Behind the Compression IMPORTANT Compression makes downloading quicker and lessens the amount of storage space needed on a hard drive.
Lossy - 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. Lossless -
Wave Form Sample Bit Rate (CBR, VBR) Sample Rate Code Word Quantization Digitalization Key Terms
Dictionary Methods Huffman Coding PCM Pulse Code Modulation DPCM Differential PCM Compression Algorithms
Specific Audio Formats – MP3 • 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
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 Specific Audio Formats – Ogg Vorbis
Advanced System Format (ASF) including: Support for Meta Data Scripting Security Features CBR & VBR (only after version 9) Industrial Support Free Codec Few Players Specific Audio Formats – WMA
Comparison WAV MP3 OGG WMA
Comparison (Cont.) From a WAV File with size 3,85 MB KB