Digital Audio File Formats

Lossy File Formats

A lossy file format is one that decreases audio quality to save file space, it is impossible to recover the lost music content once it has been saved in a lossy format. For the highest level of music playback you want to avoid using any lossy format.

  • MP3 – MP3 (responsible for kicking off the whole computer audio phenomena) is a lossy audio compression format that saves a lot of space by decreasing the musical content of the file. MP3 files are available in different compression levels such as 128kbs, 192kbs, 256kbs and 320kbs. The higher the number the lower the compression level.
  • AAC – AAC is another lossy file format similar to MP3 however for the same bit rates AAC achieves a better sound quality. Therefore, an AAC file at 256kbs sounds as good as an MP3 file at 320kbs. Developed by Sony and Dolby Labs amongst others, it is used primarily by Apple as the default file format in iTunes.
  • WMA – Windows Media Audio format or WMA is yet another lossy compressed format developed by Microsoft way back when hard drive space was at a premium. It’s relevance these days is little to be honest but there are still many files in this format and it is still an option on download sites.

Lossless File Formats

A lossless file format is one that stores the exact and complete data of a recording, with absolutely no loss of music content what so ever. There are several main file formats for lossless files:

  • FLAC – FLAC (Free Lossless Audio Codec) is without a doubt the most common lossless format as it is open source and as the name suggests, free to use. Files can be from 16bit/44.1kHz through to FLAC HD at 24bit/192kHz.
  • ALAC – ALAC or Apple Lossless Audio Codec was developed by Apple Computer as their lossless format for iTunes, although they to this date have never offered ALAC files through the iTunes store. ALAC is a variation of the FLAC format.
  • WMA Lossless – Windows Media Audio Lossless is as the name implies, a lossless verion of WMA and is generally 16bit/44.1kHz or 24bit/96kHz.
  • AIFF – AIFF or Audio Interchange File Format was developed by Apple Computer in 1988 and is based on the Electronic Arts’ Interchange File Format. AIFF is uncompressed PCM audio.
  • WAV – WAV or Waveform Audio File Format is a Microsoft/IBM audio file format developed in 1991 and uses Linear Pulse Code Modulation or LPCM. It’s uses is mainly in audio recording but is available from music download stores.
  • Other Formats – There are more file formats than those listed here, however these are the main formats you will encounter in the world of downloadable music files.

DSD Streaming

DSD or Direct Stream Digital is a one bit recording format originally developed by Sony and Philips for the creation of SACD discs. Since then Sony have used the DSD format for archiving of historical recordings believing it to be a superior format to PCM.

A number of music download sites are offering DSD files as an alternative to the PCM files listed above. With the right gear, DSD does in fact sound superior.

DSD files come in two versions, DSF and DFF. DSF files are able to store metadata and DFF files are not, simple. (Yes, there are more significant differences between the two formats, but not related to our use here)

DSD files for SACD creation are sampled at 2.8Mhz and this is generally considered the base line of DSD files. Higher quality files are available in 5.6MHz and 11.2MHz. These files are also called double rate and quad rate respectively. These same files are often referred to as DSD64, DSD 128 and DSD256 with the number referring to the multiple of standard CD rate of 44.1….confusing isn’t it?

So, for clarification here are the DSD formats with all of the possible names:

  • DSD 2.8MHz | DSD64
  • DSD 5.6MHz | DSD128 | DSD Double Rate
  • DSD 11.2MHz | DSD256 | DSD Quad Rate