Linux Blog

FLAC

Section: (1)
Updated: 02 February 2005
Index Return to Main Contents
 

NAME

flac - Free Lossless Audio Codec  

SYNOPSIS

flac [ options ] [ infile.wav | infile.aiff | infile.raw | - ... ]

flac [ -d | --decode | -t | --test | -a | --analyze ] [ OPTIONS ] [ infile.flac ... ]

 

DESCRIPTION

flac is a command-line tool for encoding, decoding, testing and analyzing FLAC streams.

FLAC stands for Free Lossless Audio Codec. Grossly oversimplified, FLAC is similar to MP3, but lossless.  

OPTIONS

A summary of options is included below. For a complete description, see the HTML documentation.  

GENERAL OPTIONS

-v, --version
Show the flac version number
-h, --help
Show basic usage and a list of all options
-H, --explain
Show detailed explanation of usage and all options
-d, --decode
Decode (the default behavior is to encode)
-t, --test
Test a flac encoded file (same as -d except no decoded file is written)
-a, --analyze
Analyze a FLAC encoded file (same as -d except an analysis file is written)
-c, --stdout
Write output to stdout
-s, --silent
Silent mode (do not write runtime encode/decode statistics to stderr)
--totally-silent
Do not print anything of any kind, including warnings or errors. The exit code will be the only way to determine successful completion.
-f, --force
Force overwriting of output files. By default, flac warns that the output file already exists and continues to the next file.
-o filename, --output-name=filename
Force the output file name (usually flac just changes the extension). May only be used when encoding a single file. May not be used in conjunction with --output-prefix.
--output-prefix=string
Prefix each output file name with the given string. This can be useful for encoding or decoding files to a different directory. Make sure if your string is a path name that it ends with a trailing `/' (slash).
--delete-input-file
Automatically delete the input file after a successful encode or decode. If there was an error (including a verify error) the input file is left intact.
--skip={#|mm:ss.ss}
Skip over the first number of samples of the input. This works for both encoding and decoding, but not testing. The alternative form mm:ss.ss can be used to specify minutes, seconds, and fractions of a second.
--until={#|[+|-]mm:ss.ss}
Stop at the given sample number for each input file. This works for both encoding and decoding, but not testing. The given sample number is not included in the decoded output. The alternative form mm:ss.ss can be used to specify minutes, seconds, and fractions of a second. If a `+' (plus) sign is at the beginning, the --until point is relative to the --skip point. If a `-' (minus) sign is at the beginning, the --until point is relative to end of the audio.
--ogg
When encoding, generate Ogg FLAC output instead of native FLAC. Ogg FLAC streams are FLAC streams wrapped in an Ogg transport layer. The resulting file should have an '.ogg' extension and will still be decodable by flac.

When decoding, force the input to be treated as Ogg FLAC. This is useful when piping input from stdin or when the filename does not end in '.ogg'.

--serial-number=#
When used with --ogg, specifies the serial number to use for the first Ogg FLAC stream, which is then incremented for each additional stream. When encoding and no serial number is given, flac uses a random number for the first stream, then increments it for each additional stream. When decoding and no number is given, flac uses the serial number of the first page.
 

ANALYSIS OPTIONS

--residual-text
Includes the residual signal in the analysis file. This will make the file very big, much larger than even the decoded file.
--residual-gnuplot
Generates a gnuplot file for every subframe; each file will contain the residual distribution of the subframe. This will create a lot of files.
 

DECODING OPTIONS

--cue=[#.#][-[#.#]]
Set the beginning and ending cuepoints to decode. The optional first #.# is the track and index point at which decoding will start; the default is the beginning of the stream. The optional second #.# is the track and index point at which decoding will end; the default is the end of the stream. If the cuepoint does not exist, the closest one before it (for the start point) or after it (for the end point) will be used. If those don't exist, the start of the stream (for the start point) or end of the stream (for the end point) will be used. The cuepoints are merely translated into sample numbers then used as --skip and --until.
-F, --decode-through-errors
By default flac stops decoding with an error and removes the partially decoded file if it encounters a bitstream error. With -F, errors are still printed but flac will continue decoding to completion. Note that errors may cause the decoded audio to be missing some samples or have silent sections.
 

ENCODING OPTIONS

-V, --verify
Verify a correct encoding by decoding the output in parallel and comparing to the original
--lax
Allow encoder to generate non-Subset files. The resulting FLAC file may not be streamable or might have trouble being played in all players (especially hardware devices), so you should only use this option in combination with custom encoding options meant for archival.
--replay-gain
Calculate ReplayGain values and store in Vorbis comments, similar to vorbisgain. Title gains/peaks will be computed for each input file, and an album gain/peak will be computed for all files. All input files must have the same resolution, sample rate, and number of channels. Only mono and stereo files are allowed, and the sample rate must be one of 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, or 48 kHz. Also note that this option may leave a few extra bytes in a PADDING block as the exact size of the tags is not known until all files are processed. Note that this option cannot be used when encoding to standard output (stdout).
--cuesheet=filename
Import the given cuesheet file and store it in a CUESHEET metadata block. This option may only be used when encoding a single file. A seekpoint will be added for each index point in the cuesheet to the SEEKTABLE unless --no-cued-seekpoints is specified.
--sector-align
Align encoding of multiple CD format WAVE files on sector boundaries. See the HTML documentation for more information.
-S {#|X|#x|#s}, --seekpoint={#|X|#x|#s}
Include a point or points in a SEEKTABLE. Using #, a seek point at that sample number is added. Using X, a placeholder point is added at the end of a the table. Using #x, # evenly spaced seek points will be added, the first being at sample 0. Using #s, a seekpoint will be added every # seconds (# does not have to be a whole number; it can be, for example, 9.5, meaning a seekpoint every 9.5 seconds). You may use many -S options; the resulting SEEKTABLE will be the unique-ified union of all such values. With no -S options, flac defaults to '-S 10s'. Use --no-seektable for no SEEKTABLE. Note: '-S #x' and '-S #s' will not work if the encoder can't determine the input size before starting. Note: if you use '-S #' and # is >= samples in the input, there will be either no seek point entered (if the input size is determinable before encoding starts) or a placeholder point (if input size is not determinable).
-P #, --padding=#
Tell the encoder to write a PADDING metadata block of the given length (in bytes) after the STREAMINFO block. This is useful if you plan to tag the file later with an APPLICATION block; instead of having to rewrite the entire file later just to insert your block, you can write directly over the PADDING block. Note that the total length of the PADDING block will be 4 bytes longer than the length given because of the 4 metadata block header bytes. You can force no PADDING block at all to be written with --no-padding. The encoder writes a PADDING block of 4096 bytes by default.
-T FIELD=VALUE, --tag=FIELD=VALUE
Add a Vorbis comment. The comment must adhere to the Vorbis comment spec; i.e. the FIELD must contain only legal characters, terminated by an 'equals' sign. Make sure to quote the comment if necessary. This option may appear more than once to add several comments. NOTE: all tags will be added to all encoded files.
-b #, --blocksize=#
Specify the block size in samples. The default is 1152 for -l 0, else 4608; must be one of 192, 576, 1152, 2304, 4608, 256, 512, 1024, 2048, 4096, 8192, 16384, or 32768 (unless --lax is used)
-m, --mid-side
Try mid-side coding for each frame (stereo input only)
-M, --adaptive-mid-side
Adaptive mid-side coding for all frames (stereo input only)
-0..-8, --compression-level-0..--compression-level-8
Fastest compression..highest compression (default is -5). These are synonyms for other options:
-0, --compression-level-0
Synonymous with -l 0 -b 1152 -r 2,2
-1, --compression-level-1
Synonymous with -l 0 -b 1152 -M -r 2,2
-2, --compression-level-2
Synonymous with -l 0 -b 1152 -m -r 3
-3, --compression-level-3
Synonymous with -l 6 -b 4608 -r 3,3
-4, --compression-level-4
Synonymous with -l 8 -b 4608 -M -r 3,3
-5, --compression-level-5
Synonymous with -l 8 -b 4608 -m -r 3,3
-6, --compression-level-6
Synonymous with -l 8 -b 4608 -m -r 4
-7, --compression-level-7
Synonymous with -l 8 -b 4608 -m -e -r 6
-8, --compression-level-8
Synonymous with -l 12 -b 4608 -m -e -r 6
--fast
Fastest compression. Currently synonymous with -0.
--best
Highest compression. Currently synonymous with -8.
-e, --exhaustive-model-search
Do exhaustive model search (expensive!)
-l #, --max-lpc-order=#
Set the maximum LPC order; 0 means use only the fixed predictors
-p, --qlp-coeff-precision-search
Do exhaustive search of LP coefficient quantization (expensive!). Overrides -q; does nothing if using -l 0
-q #, --qlp-coeff-precision=#
Precision of the quantized linear-predictor coefficients, 0 => let encoder decide (min is 5, default is 0)
-r [#,]#, --rice-partition-order=[#,]#
Set the [min,]max residual partition order (0..16). min defaults to 0 if unspecified. Default is -r 3,3.
 

FORMAT OPTIONS

--endian={big|little}
Set the byte order for samples
--channels=#
Set number of channels.
--bps=#
Set bits per sample.
--sample-rate=#
Set sample rate (in Hz).
--sign={signed|unsigned}
Set the sign of samples (the default is signed).
--input-size=#
Specify the size of the raw input in bytes. If you are encoding raw samples from stdin, you must set this option in order to be able to use --skip, --until, --cue-sheet, or other options that need to know the size of the input beforehand. If the size given is greater than what is found in the input stream, the encoder will complain about an unexpected end-of-file. If the size given is less, samples will be truncated.
--force-aiff-format
Force the decoder to output AIFF format. This option is not needed if the output filename (as set by -o) ends with .aiff. Also, this option has no effect when encoding since input AIFF is auto-detected.
--force-raw-format
Force input (when encoding) or output (when decoding) to be treated as raw samples (even if filename ends in .wav).
 

NEGATIVE OPTIONS

--no-adaptive-mid-side
--no-decode-through-errors
--no-delete-input-file
--no-exhaustive-model-search
--no-lax
--no-mid-side
--no-ogg
--no-padding
--no-qlp-coeff-precision-search
--no-residual-gnuplot
--no-residual-text
--no-sector-align
--no-seektable
--no-silent
--no-verify
These flags can be used to invert the sense of the corresponding normal option.
 

SEE ALSO

metaflac(1).

The programs are documented fully by HTML format documentation, available in /usr/doc/flac-*.*.*/doc on Slackware GNU/Linux systems.  

AUTHOR

The flac program was developed by Josh Coalson. This manual page was written by Matt Zimmerman <mdz@debian.org> for the Debian GNU/Linux system (but may be used by others).


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
GENERAL OPTIONS
ANALYSIS OPTIONS
DECODING OPTIONS
ENCODING OPTIONS
FORMAT OPTIONS
NEGATIVE OPTIONS
SEE ALSO
AUTHOR




Random Man Pages:
intro
gpl
autoheader
resolver