Good command line tool for converting to and from FLAC audio format

Command-line batch audio processing tools are sox(http://sox.sourceforge.net/) and ecasound(http://www.eca.cx/ecasound/). You may want to check man soxformat for the list of supported formats (i.e. streaming and file formats). It may be also beneficial to consider including ffmpeg(see http://ffmpeg.org/ffmpeg-all.html) into the toolchain for conversion from some of the exotic codecs into mainstream formats.

Both WAV and FLAC formats are lossless, which means they do not lose any quality from an original music CD. WAV however is uncompressed, while FLAC uses a lossless compression mechanism (pretty much like a ZIP lossless compression) specifically designed for efficient packing of audio data. FLAC files can then be played with your favorite player, just like ordinary MP3's.

If you already have WAV files, then you simply need to convert them to FLAC (and not worry about losing quality). You can either use CLI via SoX (although other solutions exist, like flac itself):

sox track_01.wav track_01.flac

Or use a clean and intuitive GUI like SoundConverter. In Preferences set output format to FLAC, choose compression speed (it does NOT affect quality, only resulting file size), then add files or a directory and start the conversion process.

Once the conversion is done, you can check that no quality was lost by using soxi (comes with SoX):

soxi track_01.wav 
soxi track_01.flac

The FLAC file size will be smaller though.

An even better way to check the technical data of an audio file is MediaInfo. See:

• How to detect real sample size and number of channels in WAV file?