Free Lossless Audio Codec, or FLAC for short, is an audio compression technique. It is a lossless compression type meaning that the compression takes place without data being discarded. FLAC is an open source codec. FLAC is a format that is recommended to those backing up a CD collection because the sound quality will remain high, whereas MP3 compression will result in a deterioration compared to the original.
Using FLAC to compress an audio file to approximately 50% of its original size. The main benefits of a FLAC file in addition to it being lossless is that it can be used for streaming, and decoding is fast, allowing for real time decoding to take place. A FLAC file also contains several data integrity checks in the header file. The metadata associated with the audio has been future proofed also to allow new fields to be defined without impacting existing decoders.
AAC is similar to MP3. It essentially cuts out, or compresses, information that the human ear cannot pick up thereby making digital files smaller and more easily managed and therefore quicker to download. AAC is about half the size of MP3 but with better quality. It is at least one tenth the size of CD digital data. Apple are the biggest users of this format and if you have an iPod or iPhone then you will have come across this format as it is iTunes default audio format.
AAC is similar in concept to MP3 but goes further. It too compresses digital audio files but to a bigger degree. It is also part of the MPEG-4 standard, it is most widely used to create small digital audio files. The current variant is specified in ISO/IEC standard 14496-3. Like MP3, AAC is a lossy algorithm. The human hearing system cannot hear quiet sounds in the presence of loud sounds of a similar frequency; for example, a voice conversation cannot be heard while an aeroplane flies low overhead. This is known as auditory masking, this allows the discarding of data with minimal loss of quality.
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