NAME¶
flac — Free Lossless Audio Codec
SYNOPSIS¶
flac [
OPTIONS] [
infile.wav |
infile.aiff |
infile.raw |
infile.flac |
infile.oga |
infile.ogg
| - ] ...
flac [-d | --decode | -t | --test | -a | --analyze ] [
OPTIONS]
[
infile.flac |
infile.oga |
infile.ogg | - ] ...
DESCRIPTION¶
flac is a command-line tool for encoding, decoding, testing and analyzing
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 successful
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.
- --keep-foreign-metadata
- If encoding, save WAVE 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 filename 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 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 them as FLAC tags,
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.
- --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 specification 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[/COLORS]]|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
picture 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 pictures 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), description
"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
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 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
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.
- --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
- -7, --compression-level-7
- Synonymous with -l 8 -b 4096 -m -e -r 6
- -8, --compression-level-8
- Synonymous with -l 12 -b 4096 -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!)
- -A function,
--apodization=function
- Window audio data with given the apodization function. The
functions are: bartlett, bartlett_hann, blackman,
blackman_harris_4term_92db, connes, flattop, gauss(STDDEV), hamming, hann,
kaiser_bessel, nuttall, rectangle, triangle, tukey(P), welch.
-
- For gauss(STDDEV), STDDEV is the standard deviation
(0<STDDEV<=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 corresponds to "hann").
-
- 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
subframe 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 predictors is faster but
usually results in files being 5-10% larger.
- -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 5.
- --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
- --no-warnings-as-errors
- 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/share/doc/libflac-doc/html on
Debian GNU/Linux systems.
AUTHOR¶
This manual page was written by Matt Zimmerman mdz@debian.org for the
Debian
GNU/Linux system (but may be used by others).