FLAC(1)FLAC(1)NAMEflac — Free Lossless Audio Codec
SYNOPSISflac [OPTIONS] [infile.wav | infile.rf64 | infile.aiff | infile.raw
| infile.flac | infile.oga | infile.ogg | - ] ...
flac [-d | --decode | -t | --test | -a | --analyze ] [OPTIONS]
[infile.flac | infile.oga | infile.ogg | - ] ...
DESCRIPTIONflac is a command-line tool for encoding, decoding, testing and analyz‐
ing FLAC streams.
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 suc‐
cessful completion.
--no-utf8-convert
Do not convert tags from local charset to UTF-8. This is
useful for scripts, and setting tags in situations where the
locale is wrong. This option must appear before any tag
options!
-w, --warnings-as-errors
Treat all warnings as errors (which cause flac to terminate
with a non-zero exit code).
-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.
--preserve-modtime
Output files have their timestamps/permissions set to match
those of their inputs (this is default). Use --no-preserve-
modtime to make output files have the current time and
default permissions.
--keep-foreign-metadata
If encoding, save WAVE, RF64, or AIFF non-audio chunks in
FLAC metadata. If decoding, restore any saved non-audio
chunks from FLAC metadata when writing the decoded file.
Foreign metadata cannot be transcoded, e.g. WAVE chunks saved
in a FLAC file cannot be restored when decoding to AIFF.
Input and output must be regular files (not stdin or stdout).
--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 '.oga'
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 file‐
name does not end in '.oga' or '.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. A CD
track can always be cued by, for example, --cue=9.1-10.1 for
track 9, even if the CD has no 10th track.
-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 sec‐
tions.
--apply-replaygain-which-is-not-lossless[=<specification>]
Applies ReplayGain values while decoding.
WARNING: THIS IS NOT LOSSLESS. DECODED AUDIO WILL NOT BE
IDENTICAL TO THE ORIGINAL WITH THIS OPTION.
The equals sign and <specification> is optional. If omitted,
the default is 0aLn1.
The <specification> is a shorthand notation for describing
how to apply ReplayGain. All components are optional but
order is important. '[]' means 'optional'. '|' means 'or'.
'{}' means required. The format is:
[<preamp>][a|t][l|L][n{0|1|2|3}]
preamp A floating point number in dB. This is added to
the existing gain value.
a|t Specify 'a' to use the album gain, or 't' to use
the track gain. If tags for the preferred kind
(album/track) do not exist but tags for the other
(track/album) do, those will be used instead.
l|L Specify 'l' to peak-limit the output, so that the
ReplayGain peak value is full-scale. Specify 'L'
to use a 6dB hard limiter that kicks in when the
signal approaches full-scale.
n{0|1|2|3}
Specify the amount of noise shaping. ReplayGain
synthesis happens in floating point; the result is
dithered before converting back to integer. This
quantization adds noise. Noise shaping tries to
move the noise where you won't hear it as much. 0
means no noise shaping, 1 means 'low', 2 means
'medium', 3 means 'high'.
For example, the default of 0aLn1 means 0dB preamp, use album
gain, 6dB hard limit, low noise shaping.
--apply-replaygain-which-is-not-lossless=3 means 3dB preamp,
use album gain, no limiting, no noise shaping.
flac uses the ReplayGain tags for the calculation. If a
stream does not have the required tags or they can't be
parsed, decoding will continue with a warning, and no Replay‐
Gain is applied to that stream.
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 encod‐
ing options meant for archival.
--replay-gain
Calculate ReplayGain values and store them as FLAC tags, sim‐
ilar 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.
--picture={FILENAME|SPECIFICATION}
Import a picture and store it in a PICTURE metadata block.
More than one --picture command can be specified. Either a
filename for the picture file or a more complete specifica‐
tion form can be used. The SPECIFICATION is a string whose
parts are separated by | (pipe) characters. Some parts may
be left empty to invoke default values. FILENAME is just
shorthand for "||||FILENAME". The format of SPECIFICATION is
[TYPE]|[MIME-TYPE]|[DESCRIPTION]|[WIDTHxHEIGHTxDEPTH[/COL‐
ORS]]|FILE
TYPE is optional; it is a number from one of:
0: Other
1: 32x32 pixels 'file icon' (PNG only)
2: Other file icon
3: Cover (front)
4: Cover (back)
5: Leaflet page
6: Media (e.g. label side of CD)
7: Lead artist/lead performer/soloist
8: Artist/performer
9: Conductor
10: Band/Orchestra
11: Composer
12: Lyricist/text writer
13: Recording Location
14: During recording
15: During performance
16: Movie/video screen capture
17: A bright coloured fish
18: Illustration
19: Band/artist logotype
20: Publisher/Studio logotype
The default is 3 (front cover). There may only be one pic‐
ture each of type 1 and 2 in a file.
MIME-TYPE is optional; if left blank, it will be detected
from the file. For best compatibility with players, use pic‐
tures with MIME type image/jpeg or image/png. The MIME type
can also be --> to mean that FILE is actually a URL to an
image, though this use is discouraged.
DESCRIPTION is optional; the default is an empty string.
The next part specfies the resolution and color information.
If the MIME-TYPE is image/jpeg, image/png, or image/gif, you
can usually leave this empty and they can be detected from
the file. Otherwise, you must specify the width in pixels,
height in pixels, and color depth in bits-per-pixel. If the
image has indexed colors you should also specify the number
of colors used. When manually specified, it is not checked
against the file for accuracy.
FILE is the path to the picture file to be imported, or the
URL if MIME type is -->
For example, "|image/jpeg|||../cover.jpg" will embed the JPEG
file at ../cover.jpg, defaulting to type 3 (front cover) and
an empty description. The resolution and color info will be
retrieved from the file itself.
The specification
"4|-->|CD|320x300x24/173|http://blah.blah/backcover.tiff"
will embed the given URL, with type 4 (back cover), descrip‐
tion "CD", and a manually specified resolution of 320x300, 24
bits-per-pixel, and 173 colors. The file at the URL will not
be fetched; the URL itself is stored in the PICTURE metadata
block.
--sector-align
Align encoding of multiple CD format files on sector bound‐
aries. See the HTML documentation for more information.
This option is DEPRECATED and may not exist in future ver‐
sions of flac.
--ignore-chunk-sizes
When encoding to flac, ignore the file size headers in WAV
and AIFF files to attempt to work around problems with over-
sized or malformed files.
WAV and AIFF files both have an unsigned 32 bit numbers in
the file header which specifes the length of audio data.
Since this number is unsigned 32 bits, that limits the size
of a valid file to being just over 4 Gigabytes. Files larger
than this are mal-formed, but should be read correctly using
this option.
-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 8192 bytes by default (or 65536
bytes if the input audio stream is more that 20 minutes
long).
-T FIELD=VALUE, --tag=FIELD=VALUE
Add a FLAC tag. The comment must adhere to the Vorbis com‐
ment spec; i.e. the FIELD must contain only legal characters,
terminated by an 'equals' sign. Make sure to quote the com‐
ment if necessary. This option may appear more than once to
add several comments. NOTE: all tags will be added to all
encoded files.
--tag-from-file=FIELD=FILENAME
Like --tag, except FILENAME is a file whose contents will be
read verbatim to set the tag value. The contents will be
converted to UTF-8 from the local charset. This can be used
to store a cuesheet in a tag (e.g. --tag-from-
file="CUESHEET=image.cue"). Do not try to store binary data
in tag fields! Use APPLICATION blocks for that.
-b #, --blocksize=#
Specify the block size in samples. Subset streams must use
one of 192, 576, 1152, 2304, 4608, 256, 512, 1024, 2048, 4096
(and 8192 or 16384 if the sample rate is >48kHz).
-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 3
-1, --compression-level-1
Synonymous with -l 0 -b 1152 -M -r 3
-2, --compression-level-2
Synonymous with -l 0 -b 1152 -m -r 3
-3, --compression-level-3
Synonymous with -l 6 -b 4096 -r 4
-4, --compression-level-4
Synonymous with -l 8 -b 4096 -M -r 4
-5, --compression-level-5
Synonymous with -l 8 -b 4096 -m -r 5
-6, --compression-level-6
Synonymous with -l 8 -b 4096 -m -r 6 -A tukey(0.5)
-Apartial_tukey(2)-7, --compression-level-7
Synonymous with -l 8 -b 4096 -m-e-r 6 -A
tukey(0.5) -Apartial_tukey(2)-8, --compression-level-8
Synonymous with -l 12 -b 4096 -m-e-r 6 -A
tukey(0.5) -Apartial_tukey(2)-Apunchout_tukey(3)--fast Fastest compression. Currently synonymous with -0.
--best Highest compression. Currently synonymous with -8.
-e, --exhaustive-model-search
Do exhaustive model search (expensive!)
-A function, --apodization=function
Window audio data with given the apodization function. The
functions are: bartlett, bartlett_hann, blackman, black‐
man_harris_4term_92db, connes, flattop, gauss(STDDEV), ham‐
ming, hann, kaiser_bessel, nuttall, rectangle, triangle,
tukey(P), partial_tukey(n[/ov[/P]]), pun‐
chout_tukey(n[/ov[/P]]), welch.
For gauss(STDDEV), STDDEV is the standard deviation (0<STD‐
DEV<=0.5).
For tukey(P), P specifies the fraction of the window that is
tapered (0<=P<=1; P=0 corresponds to "rectangle" and P=1 cor‐
responds to "hann").
For partial_tukey(n) and punchout_tukey(n), n apodization
functions are added that span different parts of each block.
Values of 2 to 6 seem to yield sane results. If necessary, an
overlap can be specified, as can be the taper parameter, for
example partial_tukey(2/0.2) or partial_tukey(2/0.2/0.5). ov
should be smaller than 1 and can be negative.
Please note that P, STDDEV and ov are locale specific, so a
comma as decimal separator might be required instead of a
dot.
More than one -A option (up to 32) may be used. Any function
that is specified erroneously is silently dropped. The
encoder chooses suitable defaults in the absence of any -A
options; any -A option specified replaces the default(s).
When more than one function is specified, then for every sub‐
frame the encoder will try each of them separately and choose
the window that results in the smallest compressed subframe.
Multiple functions can greatly increase the encoding time.
-l #, --max-lpc-order=#
Specifies the maximum LPC order. This number must be <= 32.
For Subset streams, it must be <=12 if the sample rate is
<=48kHz. If 0, the encoder will not attempt generic linear
prediction, and use only fixed predictors. Using fixed pre‐
dictors is faster but usually results in files being 5-10%
larger.
-p, --qlp-coeff-precision-search
Do exhaustive search of LP coefficient quantization (expen‐
sive!). 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..15). min
defaults to 0 if unspecified. Default is -r 5.
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, --cuesheet, 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-raw-format
Force input (when encoding) or output (when decoding) to be
treated as raw samples (even if filename ends in .wav).
--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 .aif
or .aiff. Also, this option has no effect when encoding
since input AIFF is auto-detected.
--force-rf64-format
Force the decoder to output RF64 format. This option is not
needed if the output filename (as set by -o) ends with .rf64.
Also, this option has no effect when encoding since input
RF64 is auto-detected.
--force-wave64-format
Force the decoder to output Wave64 format. This option is
not needed if the output filename (as set by -o) ends with
.w64. Also, this option has no effect when encoding since
input Wave64 is auto-detected.
Negative Options
--no-adaptive-mid-side
--no-cued-seekpoints
--no-decode-through-errors
--no-delete-input-file
--no-preserve-modtime
--no-keep-foreign-metadata
--no-exhaustive-model-search
--no-force
--no-lax
--no-mid-side
--no-ogg
--no-padding
--no-qlp-coeff-prec-search
--no-replay-gain
--no-residual-gnuplot
--no-residual-text
--no-sector-align
--no-seektable
--no-silent
--no-verify
--no-warnings-as-errors
These flags can be used to invert the sense of the corre‐
sponding normal option.
SEE ALSOmetaflac(1)
The programs are documented fully by HTML format documentation, avail‐
able in /usr/share/doc/libflac-doc/html on Debian GNU/Linux systems.
AUTHOR
This manual page was initially written by Matt Zimmerman mdz@debian.org
for the Debian GNU/Linux system (but may be used by others). It has
been kept up-to-date by the Xiph.org Foundation.
FLAC(1)
