Common Audio Formats
Most audio formats use lossy compression, to produce as small as possible a file compatible with the desired sound quality. There is a trade-off between size and sound quality of lossily compressed files; most formats allow different combinations—e.g., MP3 files may use between 32 (worst) and 320 (best) kilobits per second. Different lossy formats may give files of different sizes for the same perceived quality.
The formats supported by a particular DAP depend upon its firmware; sometimes a firmware update adds more formats. To listen to a file on a player, it must be in a supported format; format conversion on a computer is usually possible, but with loss of quality.
MP3 is the dominant format, and is almost universally supported. It is a proprietary format; manufacturers must pay a small royalty to be allowed to support it.
The main proprietary alternative formats are AAC and WMA. Unlike MP3, these formats support DRM restrictions that are often enforced by files from paid download services.
Free formats, which do not require manufacturers or music distributors to pay a fee, are available, though less widely supported. Examples include Vorbis, FLAC, and Speex.
Most players can also play uncompressed PCM in a container such as WAV or AIFF.
Read more about this topic: Portable Media Player
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