![]() Which brings us to why MP3s and low rate AAC (Apple Audio Codec used in iTunes) files suck. flac (Free Lossless Audio Codec) typically cut the file size only in half - enough for music and its smaller files sizes, but inadequate for video. This massive compression is what allows an entire feature film to be stored on a 50 gigabyte bluray disc. Lossy MPEG-4 can cut the file size by a factor of 60 or more. ![]() This begs the question, why not use lossless compression for everything? The answer lies in the amount of compression available with lossless schemes. DTS Master HD and Dolby HD, the soundtrack codecs of choice on bluray discs are lossless - a decoder in either your bluray player or receiver/processor uncompresses and plays them without any loss of quality from the original file. A computer zip file works this way, compressing a file in a way that it can be opened or unpacked back into the original file. In a lossless codec, nothing is thrown away, the data is simply packed tighter, so it’s in a smaller package. A lossy codec means some of the data is thrown away in the file shrinking process. Broadly, there are two kinds of codecs, lossy and lossless. ![]() We need something, a codec, to crunch the several terabytes of the entire film down to something more manageable. A Bluray disc holds roughly 50 gigabytes, and this needs to contain the entire film. For example, a best quality, uncompressed version of the trailer for The Amazing Spiderman comes in at 500 gigabytes. Codecs exist to shrink a movie or music files down to a more manageable size. Codec stands for coder-decoder, or less commonly, compressor/decompressor.
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