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Topic: Audio compression


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  Audio data compression - Wikipedia, the free encyclopedia
Audio compression is a form of data compression designed to reduce the size of audio data files.
Audio compression algorithms are typically referred to as audio codecs.
The primary users of lossless compression are audio engineers, audiophiles and those consumers who want to preserve the full quality of their audio files, in contrast to the quality loss from lossy compression techniques such as Vorbis and MP3.
en.wikipedia.org /wiki/Audio_data_compression   (2097 words)

  
 Compression in Audio Recordings
Compression ratios of perhaps 2:1 are common, so the output will rise (or fall) by one unit for every two units of input change.
Compression is commonly used in the final mix, and this is where things can go seriously wrong - everything is at the same volume, peak to average ratio is minimal, and the resulting sound is almost always worse than it was before the compression was applied.
Compression - A most excellent article by Bob Katz, on the perils of using compression or limiting on the final mix.
sound.westhost.com /compression.htm   (3919 words)

  
 A Recording Engineer's Plea for Dynamic Range
Since the loudness of a LP or single is subject to a the physical limitations of the medium, the way to make a record, especially a 45 rpm single, louder was to compress it heavily, much as commercial radio stations do to sound loud on the air.
The digital audio medium also has its maximum upper limit in level, in this case all digital "ones." So to make the music sounder louder more of the time, that means adding compression, just like the bad old days of 45s.
The fallacy that seems to have become pervasive among many people in the pop music recording field, especially among record companies, is that if a CD is pushing the absolute digital max it will somehow be louder or better on the air and presumably win more airplay, and thus sell more copies to the public.
georgegraham.com /compress.html   (1728 words)

  
 Harmony Central®: Effects Explained: Compression/Limiting
It is used extensively in audio recording, production work, noise reduction, and live performance applications, but it does need to be used with care.
One popular use of compression is to increase an instrument's sustain.
A little compression will keep the instrument's level from changing radically after it's plucked, which is perceived as increased sustain or a 'smoothing' of instrument.
www.harmony-central.com /Effects/Articles/Compression   (1713 words)

  
 Audio compression - Wikipedia, the free encyclopedia
Audio data compression - in which the amount of data in a recorded waveform is reduced for transmission.
This is used in MP9 encoding, internet radio, and the like.
Audio level compression - in which the dynamic range (difference between loud and quiet) of an audio waveform is reduced.
en.wikipedia.org /wiki/Audio_compression   (132 words)

  
 dBpowerAMP
Audio is made up from 1000's of data values, the higher the number of data values the better sounding it will be (up to a point).
Monkeys Audio is a what you would call a lossless compressor, that is when a monkeys audio file is played the resulting rendition is exactly the same (quality wise) as the original.
The most basic of all audio formats, in it's native form (PCM) audio data is stored uncompressed, when an Audio CD is converted to a wave file the resulting wave file is 16 Bit, Stereo with a sample frequency of 44.1Khz, this gives 172K bytes per second of audio data, or 10MBs per minute.
www.dbpoweramp.com /spoons-audio-guide-formats.htm   (2437 words)

  
 Howstuffworks "How MP3 Files Work"
It is "perceptual" partly because the MP3 format uses characteristics of the human ear to design the compression algorithm.
Compressing the rest of the song with well-known compression techniques shrinks the song considerably -- by a factor of 10 at least.
It is simply a file format that compresses a song into a smaller size so it is easier to move around on the Internet and store.
www.howstuffworks.com /mp31.htm   (704 words)

  
 Digital audio gets an audition part one: lossless compression - 1/4/2001 - EDN   (Site not responding. Last check: 2007-11-05)
Lossless compression may also make sense for musicians and audio engineers who want to temporarily store tracks prior to editing and mixing and archive the final master tracks for future fame and fortune, or folks who decide to digitize those LP records collecting dust in their garages.
Lossless compression results depend greatly on the characteristics of the source material: for example, total frequency range that the material spans; the amount of sample-to-sample frequency variation; whether the material is monophonic or stereo; and, if the material is stereo, the difference in the channels' frequency, amplitude, and phase.
The fact that a "compressed" version of a highly random data pattern is larger than the pattern itself isn't a surprise; this phenomenon results from the control bit and other overhead of the compression scheme.
www.edn.com /article/CA60895.html   (3119 words)

  
 Digital Compression   (Site not responding. Last check: 2007-11-05)
In a lossy compression scheme, as the name implies, some of the original information is discarded when it is compressed.
One proponent of Lossless Compression is Etree.org a music distribution hub but not for audio that has been compressed in a lossy fashion like MP3 or AAC but for audio that has been compressed in a lossless way.
Etree.org uses the Shorten (.shn) audio compression format because it creates an exact clone of the original source.
www.puredigitalaudio.org /digitalcompression/index.shtml   (713 words)

  
 DataCompression.info - Audio   (Site not responding. Last check: 2007-11-05)
Audio compression is a little bit different from Speech compression.
Compression is one of them, and there is certainly a great deal to learn about compression and media formats at this conference.
Like other lossless compression schemes the data reduction varies with the source, but it is generally between 25% and 50% for typical popular music and somewhat better than that for classical music and other sources with greater dynamic range.
datacompression.info /Audio.shtml   (8863 words)

  
 The Ins and Outs of Audio Compression
If you've ever extracted an audio cd to your PC as a wav then you will know that uncompressed digital audio can be seriously bigger than the mp3s you get off the 'net.
In audio there are a few codecs that can but a popular lossless codec is Monkey's Audio codec which is quite cool.
Most audio is compressed at a Constant Bitrate (CBR), which means that every second will have the same amount of bits available to it (there is a bit reservoir but essentially you are fixed to the amount of data per second).
www.animemusicvideos.org /guides/avtech/audio2.html   (1541 words)

  
 Lossless audio compression
The question of compressing audio without any loss of quality (including especially without having to even think about how lossy a lossy algorithm is, because the binary bits are fully restored) is obviously important.
Compression of these 6 second samples will no-doubt produce different ratios then compressing the entire file, due to variations in the sound signal from moment to moment.
Compressing one section of a test file (03CC.wav) he found that the Windows and Macintosh file sizes were 57.03% and 56.50% respectively.
www.firstpr.com.au /audiocomp/lossless   (8593 words)

  
 The Lossless Audio Blog
A term describing a data compression algorithm which retains all the information in the data, allowing it to be recovered perfectly by decompression.
I was extremely busy at the time and so I took a quick look at there website and decided to check the Hydrogen Audio forums to see what the folks at HA were saying about it.
It is a great place to learn and keep up to date on audio technology and if there is a new lossless format on the rise you can bet that the folks at HA know about it and can provide some good incite into it.
losslessaudio.blogspot.com   (826 words)

  
 OGG vs. MP3 vs. WMA vs. RA
OSSY AUDIO COMPRESSION can be quickly described as the JPG of music: for a minor loss of quality we have a sound file which is many times smaller to the original and it can be easily broadcasted through the internet or transferred on portable media.
WMA is a lossy audio compression algorithm which works only as part of the Windows media player and not as a standard Windows codec (so that you may not convert WMA files to other formats).
Real Audio is one of the oldest formats for compressed audio; it was first designed for voice applications on the web but later it developed music and video algorithms as well.
ekei.com /audio   (2824 words)

  
 Lossless Audio Homepage
La is a lossless audio compressor featuring the highest available compression of any such program.
That is, in contrast to formats such as mp3, it reduces the size of music without affecting the quality, as the uncompressed signal is exactly identical to the original.
However, the compression ratio is thus far lower than that for.mp3 files - you can expect around 50%, worse for heavier music and better for classical etc.
www.lossless-audio.com   (180 words)

  
 IMA audio compression for QuickTime files   (Site not responding. Last check: 2007-11-05)
Audio compression is often your worst nightmare when dealing with multimedia applications or digital video.
While most digital video compression codecs do a good job reducing the size of the video images, they don't reduce the size of the soundtrack very much.
IMA audio compression reduces the size of your audio file by a factor of 4, resulting in a 75% saving.
members.aol.com /JordanGold/IMAmain.html   (704 words)

  
 FLAC - format   (Site not responding. Last check: 2007-11-05)
It is a known fact that no algorithm can losslessly compress all possible input, so most compressors restrict themselves to a useful domain and try to work as well as possible within that domain.
Note that when we talk about blocks and subblocks we are refering to the raw unencoded audio data that is the input to the encoder, and when we talk about frames and subframes, we are refering to the FLAC-encoded data.
FLAC specifies a minimum block size of 16 and a maximum block size of 65535, meaning the bit patterns corresponding to the numbers 0-15 in the minimum blocksize and maximum blocksize fields are invalid.
flac.sourceforge.net /format.html   (4314 words)

  
 LPAC - Lossless Predictive Audio Compression
To play compressed files directly there is a LPAC plug-in for Winamp.
After you have specified a directory where to copy the files, the audio tracks are successively grabbed and compressed.
They are supplied for people interested in audio compression and may be used by anyone for a noncommercial purpose.
www.nue.tu-berlin.de /wer/liebchen/lpac.html   (1705 words)

  
 Switch Sound File Conversion Software - Audio File Format Converter Software for Windows
It can convert audio files from many different file formats into mp3 or wav files, including wav to mp3, au to mp3, aiff to mp3 and much more.
Converts a variety of different audio file formats including wav, mp3, ogg, flac, aac, wma, au, aiff, ogg, msv, dvf, vox, atrac, gsm, dss and other formats into mp3 or wav, plus more formats supported.
Switch audio file converter is just one component of the NCH Swift Sound suite of audio software for business.
www.nch.com.au /switch   (653 words)

  
 MPEG . ORG - MPEG Audio Resources and Software
Section 6 of this large document is an introduction and overview of the subset of the MPEG-2 Audio standard used for HDTV.
MPEG Audio Layer 1 & 2 decoder and encoder for Macintosh (MPEGAud) by George Warner M-Back v0.82 for Windows and mplay v1.2 for DOS.
MPEG Audio Layer 3 test bitstreams can be found on the MP3 Page.
www.mpeg.org /MPEG/audio.html   (1285 words)

  
 Video and Audio Compression
Unless we develop and maintain very high bandwidth networks (Gigabytes per second or more) we have to compress to data.
As we will compression becomes part of the representation or coding scheme which have become popular audio, image and video formats.
We will first study basic compression algorithms and then go on to study some actual coding formats.
www.cs.cf.ac.uk /Dave/Multimedia/node200.html   (109 words)

  
 WavPack Audio Compression
WavPack is a completely open audio compression format providing lossless, high-quality lossy, and a unique hybrid compression mode.
The compression ratio depends on the source material, but generally is between 30% and 70%.
Instead of creating a single file, this mode creates both a relatively small, high-quality lossy file that can be used all by itself, and a "correction" file that (when combined with the lossy file) provides full lossless restoration.
www.wavpack.com   (563 words)

  
 Close-Up with Joe Fedele - The Audio & Video Compression Page   (Site not responding. Last check: 2007-11-05)
Digital compression techniques have revolutionized the storage and transfer of audio and video information.
MPEG - A compression scheme for M - O - V - I - N - G pictures.
Compression - General information not necessarily tied to only one compression scheme.
www.fedele.com /website/compress/compress.htm   (261 words)

  
 Audio Compression
When I bought my 30GB iPod, I had to decide which audio compression scheme I wanted to use for encoding my 300 to 400 CDs.
I've encoded a 3 second 128 kbit/sec VBR MP3 file of this track, to give you an impression what I'm talking about (due to copyright reasons I keep the sample short and low quality).
In sound quality when talking about lossy audio what counts is the amount and *type* of the audible quantization noise.
members.chello.nl /~m.heijligers/ipod/Compression/compression.html   (2792 words)

  
 etree.org | mkw Audio Compression Tool
The mkw Audio Compression Tool (mkwACT) is a free Windows® 95/98/Me and NT/2000 and XP program created for the easy and convenient conversion of WAV audio files to and from various lossless and lossy compressed formats, including Shorten (SHN).
Next, the mkwACT Setup will add program icons to the Program Folder listed in the text box (by default, it will be "mkw Audio Compression Toolkit").
You're now ready to compress and decompress files with the glorious Shorten lossless audio format!
www.etree.org /mkw.html   (1389 words)

  
 Wave File Compression Codecs Compared - Audio Compression Manager (ACM)
This is a reference to compare the audio quality and compression bitrates of the different wave compression codecs available for ".wav" and ".dct" files using the audio compression manager including PCM, GSM, ADPCM, CELP, SBC, TrueSpeech and MPEG Layer-3.
The audio file compression formats listed on this page are low bitrate speech formats.
You can listen to samples of each audio format by clicking on the "Sample" link.
www.nch.com.au /acm   (234 words)

  
 Monkey's Audio - a fast and powerful lossless audio compressor
Monkey’s Audio is a fast and easy way to compress digital music.
Even though the sound is perfect, it still saves a lot of space.
That way, you'll never have to recopy your CD collection to switch formats, and you'll always be able to recreate the original music CD if something ever happens to yours.
www.monkeysaudio.com   (307 words)

  
 BDTI - Audio Compression Algorithm Implementations Table
BDTI has extensive experience in the development of digital audio
implementations of digital audio compression (and decompression) algorithms.
If you have created (or know of) an optimized implementation of a digital audio compression algorithm that
www.bdti.com /articles/ACAI_table.html   (424 words)

  
 Video & Audio Compression Cards,Security Surveillance Systems,Internet Transmitters,Others
Chenova PSHH series V/A compression card adopts H.264 compression algorithm and pure hardware technology to implement V/A signal realtime coding
Pure hardware video compression based on the algorithm of H.264, not consuming CPU resource
Features: 1) Uses H.264 compression algorithm for pure hardware compression 2) 4 channel video signal and 4 channel audio
chenova.en.alibaba.com /group/0.html   (348 words)

  
 MPEG . ORG - Other Video and Audio Compression Sites   (Site not responding. Last check: 2007-11-05)
Indexes to resources related to video and audio compression.
Video compression, videoconferencing, and image compression pointers by Frank Hartung at Universität Erlangen-Nürnberg Lehrstuhl für Nachrichtentechnik (LNT)
Data Compression Laboratory at University of Washington (new) - VQ and wavelets
www.mpeg.org /~tristan/MPEG/links.html   (296 words)

  
 Vorbis.com   (Site not responding. Last check: 2007-11-05)
To obtain the source code, please see the xiph download page.
Ogg Vorbis is a completely open, patent-free, professional audio encoding and streaming technology with all the benefits of Open Source.
View our list of 3rd Party Software that uses Vorbis.
www.vorbis.com   (55 words)

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