FLAC is a lossless codec, meaning no audio quality is lost whilst compressing (unlike lossy codecs such as mp3 which throw audio data away), audio compressed to a lossless codec will be decoded identical to the source, think of it as zip for audio. All lossless codecs compress around 2:1 or 4:1 at best, a 3 minute audio track will be around 18 MB.

Supported by this Codec

• Encoding: Yes   [.flac]
• Multi-processor Encoding: Yes   (with dBpoweramp reference)
• Decoding: Yes   [.flac  .fla (optional)]
• ID Tag Reading: Yes   [Vorbis Comments]
• ID Tag Writing: Yes   [Vorbis Comments]
• Unicode Tagging: Yes
• Supports Album Art: Yes
• Gapless Encoding & Decoding: Yes
• Unicode Filenames: Yes

Compression Options

Being a lossless codec there are not many options to set when compressing to FLAC:

Compression affects how much effort goes into compressing the audio, all compression modes give the same decoded audio (it is lossless after all), the higher compression levels will give a small % file size saving, but will require more time to compress and decompress. Compression Level 0 requires the least compression time, whilst Compression Level 8 the most. Uncompressed is a special compression mode with stores 16 bit audio in an uncompressed state.

After Encoding Verify Written Audio once compression is complete the compressed audio will be read and compared to the source, verifying the compression is without error (hard disk, or very unlikely codec induced).

Codec Background

FLAC is a acronym for Free Lossless Audio Codec, and is a popular open source cross-platform codec. FLAC falls under the Ogg banner (Vorbis, Speex and FlAC). Primarily developed by Josh Coalson.

More Details:   http://flac.sourceforge.net/


ID Tag Details

FLAC supports Vorbis Comments, these are present at the beginning of the file and allow Unicode tagging. Vorbis Comments are not limited to fixed fields, but a lack of standardized extended tag values (ratings, etc) limit Vorbis Comments.


Advanced Options

dBpoweramp Configuration offers advanced options for this codec (dBpoweramp Control Center >> Audio Codecs 'List / Options'):

FLAC ID Tagging

Vorbis Comment Mapping, sadly there are many programs which do not follow the official guidelines for Vorbis Comment tagging (in Vorbis comments 'Label' tag should be stored as 'Organization'), to cater for these programs, mappings can be switched off (so Label would be saved as Label).

FLAC Decoder

Corrupt FLAC File gives the option to ignore any errors and continue to decode the file (errors will be shown as information at the end).

Associate with .fla Files the extension .fla is also used for Flash animation, so can be a conflict of file types.

FLAC Encoder

FLAC ID Tag Padding as Vorbis Comments are at the beginning of the file it is advantageous to insert padding so if the ID Tags change then the whole file does not need rewriting.

Command Line

dBpoweramp Reference allows compressions from the command-line, commands specific to this codec:

-compression-level-0       set compression levels (0 worst, 8 best, 5 default)
-compression-level-1
-compression-level-2
-compression-level-3
-compression-level-4
-compression-level-5       (default)
-compression-level-6
-compression-level-7
-compression-level-8

-verify                             verifies compressed audio (by reading back from hard disk)


Example:   "c:\program files\illustrate\dBpoweramp\coreconverter.exe" -infile="c:\afile.wav" -outfile="c:\outfile.flac" -convert_to="FLAC" -compression-level-2 -verify

Terminology

Encoding:  compress and write audio track,
Decoding:  uncompress and read the track,
ID Tags:  meta data such as artist & album are embedded inside the audio file,
Lossless:  compression without audio quality loss,
Lossy:  audio quality is sacrificed (how much depends on bitrate and codec used) to achieve smaller files,
Gapless:  allows the decoder to decode audio stream without gaps (silence),
Explorer Audio Popup:  a dBpoweramp function, hold the mouse over a supported audio file and details contained are displayed,
Multi-processor Encoding:  for multi core processors multiple files can be compressed at once fully using all cores.
Command Line:  text interface, where commands are typed (start >> run >> cmd  to get to the command line)

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