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Old 2010-10-21, 05:51 AM
TomB TomB is offline
 
Join Date: Oct 2009
Re: Using TLH test for MPEG evidence?

Quote:
Originally Posted by showtaper View Post
Google is your friend:

FLAC (excerpt from wikipedia)

Free Lossless Audio Codec (FLAC) is an audio compression codec primarily authored by Josh Coalson and Ed Whitney. As its name implies, FLAC employs a lossless data compression algorithm: a digital audio recording compressed by FLAC can be decompressed into an identical copy of the original audio data. Audio sources encoded to FLAC are typically reduced to 50–60% of their original size.

Lossless Data Compression (excerpt from wikipedia)

Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. The term lossless is in contrast to lossy data compression, which only allows an approximation of the original data to be reconstructed, in exchange for better compression rates.

Lossless data compression is used in many applications. For example, it is used in the popular ZIP file format and in the Unix tool gzip. It is also often used as a component within lossy data compression technologies (e.g. lossless mid/side joint stereo preprocessing by the LAME MP3 encoder and other lossy audio encoders).

Lossless compression is used in cases where it is important that the original and the decompressed data be identical, or where deviations from the original data could be deleterious. Typical examples are executable programs, text documents and source code. Some image file formats, like PNG or GIF, use only lossless compression, while others like TIFF and MNG may use either lossless or lossy methods. Lossless audio formats are most often used for archiving or production purposes, with smaller lossy audio files being typically used on portable players and in other cases where storage space is limited and/or exact replication of the audio is unnecessary.

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There are a number of lossless compression codecs, you can find a large number of more technical explanations with a search engine and a little effort.......
There a boundless 'explanations' of the codec out there, but it seems to me that most of them are 'fluffed up' narrative, only explaining the concept... The only place I seem to be able to find any 'meat' is on the authors page. Even then it seems the critical parts like how it is more 'efficient' than most other codecs when it comes to SR errors and problems with other system's codecs decoding the signals... I get the fact that because it uses a different style math/predictors it takes less data to transfer the original information....
HOWEVER, my challenge to the concept, if you put it back into layperson terms is this:
Sure, about 98% of us could use a zip file graphic for our websites, but if we were making billboards, then we would certainly want the original, non-zipped file. If we took the zipped file to its limits, then we would certainly see evidence of it's zipping... I would think the same holds true for audio.... so, when one walks around brandishing the term lossless, it is really misleading, since in effect, no matter how you spin it, if you take a file that was one size and reduce it to a smaller size - THIS IS A LOSS, BY DEFINITION !!
I am only challenging the 'purists' conviction that flac is truly lossless ! Shouldn't it be called 'least lossy', if you are truly a 'purist' ??
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