diff --git a/flac/bitstream/bitstream.factor b/flac/bitstream/bitstream.factor
new file mode 100644
index 0000000..22b0b19
--- /dev/null
+++ b/flac/bitstream/bitstream.factor
@@ -0,0 +1,45 @@
+! Copyright (C) 2009 Daniel Ehrenberg
+! See http://factorcode.org/license.txt for BSD license.
+USING: kernel system destructors accessors byte-arrays math locals io.files io.encodings.binary combinators sequences namespaces ;
+QUALIFIED: bitstreams
+QUALIFIED: io
+USING: prettyprint ;
+
+IN: flac.bitstream
+
+CONSTANT: default-bitreader-capacity 65536
+SYMBOL: flac-input-stream
+
+TUPLE: flac-stream-reader stream bitstream ;
+
+GENERIC: read-uint ( n flac-stream-reader -- n )
+GENERIC: align-to-byte ( flac-stream-reader -- )
+
+: <flac-stream-reader> ( path -- flac-stream-reader )
+    binary <file-reader> B{ } bitstreams:<msb0-bit-reader> flac-stream-reader boa ;
+
+M: flac-stream-reader dispose stream>> dispose ;
+
+: flac-align-to-byte ( -- )
+    8 flac-input-stream get bitstream>> bitstreams:align ;
+
+: flac-read-uint ( n -- n )
+    [ dup flac-input-stream get bitstream>> bitstreams:enough-bits? not ]
+    [
+        flac-input-stream get
+        [ stream>> default-bitreader-capacity swap io:stream-read ] [ bitstream>> ] bi
+        dup bytes>> swap [ prepend ] dip swap >>bytes drop
+    ] while flac-input-stream get bitstream>> bitstreams:read ;
+
+: flac-read-sint ( n -- n )
+    ! TODO: this isn't rightt
+    dup flac-read-uint dup . dup 1 - neg shift swap shift ;
+
+: with-flac-stream-reader* ( flac-bitstream quot -- )
+    flac-input-stream swap with-variable ; inline
+
+: with-flac-stream-reader ( flac-bitstream quot -- )
+    [ with-flac-stream-reader* ] curry with-disposal ; inline
+
+: with-flac-file-reader ( filename quot -- )
+    [ <flac-stream-reader> ] dip with-flac-stream-reader ; inline
diff --git a/flac/decoder/decoder.factor b/flac/decoder/decoder.factor
new file mode 100644
index 0000000..6003374
--- /dev/null
+++ b/flac/decoder/decoder.factor
@@ -0,0 +1,216 @@
+! Copyright (C) 2020 .
+! See http://factorcode.org/license.txt for BSD license.
+USING: math io.encodings.binary kernel io io.files locals endian bit-arrays math.intervals combinators combinators.extras math.order math.bits sequences namespaces accessors byte-arrays math.bitwise arrays ;
+USING: prettyprint ;
+USING: flac.bitstream flac.metadata flac.format ;
+
+IN: flac.decoder
+
+! : unary-code ( q -- bit-array )
+!     on-bits 1 shift integer>bit-array ;
+! 
+! :: truncated-binary-code ( r m -- bit-array )
+!     m log2 :> b
+!     b 1 + 2^ m - :> cutoffs
+!     r cutoffs <
+!     [ r b <bits> ] [ r cutoffs + b 1 + <bits> ] if
+!     >bit-array ;
+
+:: rice-encode ( n m -- bit-array )
+    n m / >integer :> q
+    n m mod :> r
+
+    q on-bits 1 shift integer>bit-array :> qcode
+
+    m log2 :> b
+    b 1 + 2^ m - :> cutoffs
+    r cutoffs <
+    [ r b <bits> ] [ r cutoffs + b 1 + <bits> ] if >bit-array :> rcode
+
+    rcode qcode append ;
+
+
+! : rice-encode ( s k -- bit-array )
+!     [ dup [ 2^ 1 - bitand ] dip <bits> >bit-array ]
+!     [ -1 * shift unary integer>bit-array ] 2bi append ;
+!    s k 2^ 1 - bitand k <bits> >bit-array
+!    s k -1 * shift unary integer>bit-array append ;
+
+:: inverted-unary ( n -- bit-array )
+    n 2^ integer>bit-array :> coding
+    coding set-bits
+    f n coding set-nth
+    coding ;
+
+: read-utf8-uint ( -- n )
+    0 [ 1 flac-read-uint 1 = ] [ 1 + ] while
+    dup [ 7 swap - flac-read-uint ] dip
+    <iota> [
+        drop
+        2 flac-read-uint drop
+        6 shift 6 flac-read-uint bitor
+    ] each ;
+
+: decode-block-size ( n -- n )
+    dup
+    {
+        { [ 0b0000 = ] [ drop reserved-block-size ] }
+        { [ 0b0001 = ] [ drop 192 ] }
+        { [ 0b0010 0b0101 between? ] [ 2 - 2^ 567 * ] }
+        { [ 0b0110 0b0111 between? ] [ ] }
+        { [ 0b1000 0b1111 between? ] [ 8 - 2^ 256 * ] }
+    } cond-case ;
+
+: decode-bits-per-sample ( n -- n )
+    {
+        { 0b000 [ "TODO" ] }
+        { 0b001 [ 8 ] }
+        { 0b010 [ 12 ] }
+        { 0b011 [ "TODO" ] }
+        { 0b100 [ 16 ] }
+        { 0b101 [ 20 ] }
+        { 0b110 [ 24 ] }
+        { 0b111 [ "TODO" ] }
+    } case ;
+
+: decode-sample-rate ( n -- n )
+    {
+        { 0b0000 [ "TODO" ] }
+        { 0b0001 [ 88200 ] }
+        { 0b0010 [ 17640 ] }
+        { 0b0011 [ 19200 ] }
+        { 0b0100 [ 8000 ] }
+        { 0b0101 [ 16000 ] }
+        { 0b0110 [ 22050 ] }
+        { 0b0111 [ 24000 ] }
+        { 0b1000 [ 32000 ] }
+        { 0b1001 [ 44100 ] }
+        { 0b1010 [ 48000 ] }
+        { 0b1011 [ 96000 ] }
+        { 0b1100 [ 8 flac-read-uint 1000 * ] }
+        { 0b1101 [ 16 flac-read-uint ] }
+        { 0b1110 [ 16 flac-read-uint 10 * ] }
+        { 0b1111 [ invalid-sample-rate ] }
+    } case ;
+
+: decode-channels ( n -- channels channel-assignment )
+    dup
+    {
+        { [ dup 0b0000 0b0111 between? ] [ 1 + ] }
+        { [ 0b1000 0b1010 between? ] [ 2 ] }
+        [ invalid-channel-assignment ]
+    } cond swap
+    <flac-channel-assignment> ;
+
+: read-flac-subframe-constant ( frame-header subframe-header -- constant-subframe )
+    drop bits-per-sample>> flac-read-uint flac-subframe-constant boa ;
+
+: read-residual-coding-method-type ( -- coding-method )
+    2 flac-read-uint dup
+    2 > [ reserved-residual-coding-type ] when
+    <flac-entropy-coding-method-type> ;
+
+:: read-residual-partitioned-rice ( frame-header subframe-header -- rice residual )
+    4 flac-read-uint :> partition-order
+    partition-order .
+    frame-header blocksize>> -1 partition-order * shift :> samples
+    samples .
+    1 partition-order shift 4 <array> [
+        dup . 
+        flac-read-uint :> param
+        param 0b1111 =
+        [ 5 flac-read-uint :> numbits samples numbits <array> [ flac-read-uint ] map drop "dicks" . param ]  
+        [ samples param <array> [ flac-read-uint ] map first . "balls" . param dup . ] if
+    ] map :> parameters
+    parameters .
+    partition-order
+    flac-entropy-coding-method-partitioned-rice-contents new
+    flac-entropy-coding-method-partitioned-rice boa parameters ;
+
+: read-residual-partitioned-rice2 ( frame-header subframe-header -- rice residual )
+    2drop flac-entropy-coding-method-partitioned-rice-contents new f ;
+
+: read-flac-residuals ( frame-header subframe-header -- entropy-coding-method residual )
+    read-residual-coding-method-type
+    [ [ read-residual-partitioned-rice ] [ read-residual-partitioned-rice2 ] if ] keep swap
+    flac-entropy-coding-method boa dup . ;
+
+: read-flac-subframe-warmup-samples ( frame-header subframe-header -- seq )
+    [ bits-per-sample>> ] [ pre-order>> ] bi* swap <repetition> [ flac-read-uint ] map ;
+
+: read-flac-subframe-fixed ( frame-header subframe-header -- fixed-subframe )
+    2dup [ read-flac-subframe-warmup-samples ] [ read-flac-residuals ] 2bi*
+    flac-subframe-fixed boa ;
+
+: decode-flac-subframe-type ( n -- type order )
+    dup
+    {
+        { [ 0 = ] [ drop f 0 ] }
+        { [ 1 = ] [ drop f 1 ] }
+        { [ 8 12 between? ] [ 8 - 2 ] }
+        !        { [ 8 12 between? ] [ -1 shift 7 bitand 2 ] }
+        { [ 32 63 between? ] [ -1 shift 31 bitand 3 ] } ! TODO: is this right?
+        [ drop reserved-subframe-type ]
+    } cond-case
+    <flac-subframe-type> swap ;
+
+: read-flac-subframe-header ( -- subframe-header )
+    1 flac-read-uint 1 = [ invalid-subframe-sync ] when
+    6 flac-read-uint decode-flac-subframe-type
+    1 flac-read-uint
+    flac-subframe-header boa ;
+
+: read-flac-subframe ( frame-header -- subframe )
+    read-flac-subframe-header dup dup
+    [
+        subframe-type>>
+        {
+            { subframe-type-constant [ read-flac-subframe-constant ] }
+            { subframe-type-fixed [ read-flac-subframe-fixed ] }
+        } case
+    ] dip swap
+    flac-subframe boa ;
+
+: read-flac-subframes ( frame-header -- seq )
+    dup channels>> swap <repetition> [ read-flac-subframe ] map ;
+
+: read-flac-frame-header ( -- frame-header )
+    14 flac-read-uint drop ! ignore sync
+    1 flac-read-uint drop ! reserved
+    1 flac-read-uint
+    4 flac-read-uint
+    4 flac-read-uint
+    4 flac-read-uint
+    3 flac-read-uint
+    1 flac-read-uint drop ! ignore magic sync for now
+    read-utf8-uint
+    [
+        {
+            [ <flac-frame-number-type> ]
+            [ decode-block-size ]
+            [ decode-sample-rate ]
+            [ decode-channels ]
+            [ decode-bits-per-sample ]
+        } spread
+    ] dip
+    8 flac-read-uint
+    flac-frame-header boa ;
+
+: read-flac-frame-footer ( -- frame-footer )
+    16 flac-read-uint flac-frame-footer boa ;
+
+: read-flac-frame ( -- frame )
+    read-flac-frame-header dup
+    read-flac-subframes
+    read-flac-frame-footer
+    flac-frame boa ;
+
+: read-flac-file ( filename -- flac-stream )
+    [
+        read-flac-metadata drop
+        read-flac-frame drop
+        read-flac-frame drop
+        read-flac-frame drop
+        read-flac-frame
+
+    ] with-flac-file-reader ;
diff --git a/flac/format/format.factor b/flac/format/format.factor
new file mode 100644
index 0000000..d444e1b
--- /dev/null
+++ b/flac/format/format.factor
@@ -0,0 +1,247 @@
+! Copyright (C) 2020 .
+! See http://factorcode.org/license.txt for BSD license.
+USING: alien.syntax math byte-arrays sequences kernel strings arrays assocs ;
+
+IN: flac.format
+
+CONSTANT: FLAC-MAGIC 0x664c6143 ! fLaC
+CONSTANT: sync-code 0b11111111111110
+
+CONSTANT: MIN-BLOCK-SIZE 16
+CONSTANT: MAX-BLOCK-SIZE 65535
+CONSTANT: MAX-SAMPLE-SIZE: 4608
+CONSTANT: MAX-CHANNELS 8
+CONSTANT: MIN-BITS-PER-SAMPLE 4
+CONSTANT: MAX-BITS-PER-SAMPLE 32 ! The value is ((2^16) - 1) * 10
+CONSTANT: MAX-LPC-ORDER 32
+CONSTANT: MAX-LPC-ORDER-48000HZ 12
+CONSTANT: MIN-QLP-COEFF-PRECISION 5
+CONSTANT: MAX-QLP-COEEF-PRECISION 15
+CONSTANT: MAX-FIXED-ORDER 4
+CONSTANT: MAX-RICE-PARTITION-ORDER 15
+
+ERROR: not-a-flac-file ;
+ERROR: sync-code-error ;
+ERROR: invalid-channel-assignment ;
+ERROR: reserved-block-size ;
+ERROR: invalid-sample-rate ;
+ERROR: reserved-subframe-type ;
+ERROR: invalid-subframe-sync ;
+ERROR: reserved-residual-coding-type ;
+
+ENUM: flac-frame-number-type
+    frame-number-type-frame
+    frame-number-type-sample ;
+
+ENUM: flac-channel-assignment
+    channels-mono
+    channels-left/right
+    channels-left/right/center
+    channels-left/right/left-surround/right-surround
+    channels-left/right/center/left-surround/right-surround
+    channels-left/right/center/lfe/left-surround/right-surround
+    channels-left/right/center/lfe/center-surround/side-left/side-right
+    channels-left/right/center/lfe/left-surround/right-surround/side-left/side-right
+    channels-left
+    channels-right
+    channels-mid ;
+
+TUPLE: flac-frame-header
+    { number-type maybe{ frame-number-type-frame frame-number-type-sample } }
+    { blocksize integer }
+    { sample-rate integer }
+    { channels integer }
+    { channel-assignment
+      maybe{ channels-mono
+             channels-left/right
+             channels-left/right/center
+             channels-left/right/left-surround/right-surround
+             channels-left/right/center/left-surround/right-surround
+             channels-left/right/center/lfe/left-surround/right-surround
+             channels-left/right/center/lfe/center-surround/side-left/side-right
+             channels-left/right/center/lfe/left-surround/right-surround/side-left/side-right
+             channels-left
+             channels-right
+             channels-mid } }
+    { bits-per-sample integer }
+    { frame|sample-number integer }
+    { crc integer } ;
+
+ENUM: flac-subframe-type
+    subframe-type-constant
+    subframe-type-verbatim
+    subframe-type-fixed
+    subframe-type-lpc ;
+
+ENUM: flac-entropy-coding-method-type
+    entropy-coding-partitioned-rice
+    entropy-coding-partitioned-rice2 ;
+
+TUPLE: flac-entropy-coding-method-partitioned-rice-contents
+    { parameters sequence }
+    { raw-bits integer }
+    { capacity-by-order integer } ;
+
+TUPLE: flac-entropy-coding-method-partitioned-rice
+    { order integer }
+    { contents flac-entropy-coding-method-partitioned-rice-contents } ;
+
+TUPLE: flac-entropy-coding-method
+    { type maybe{ entropy-coding-partitioned-rice
+                  entropy-coding-partitioned-rice2 } }
+    { data flac-entropy-coding-method-partitioned-rice } ;
+
+TUPLE: flac-subframe-constant
+    { value integer } ;
+
+TUPLE: flac-subframe-verbatim
+    { data byte-array } ;
+
+TUPLE: flac-subframe-fixed
+    { warmup sequence }
+    { entropy-coding-method flac-entropy-coding-method }
+    residual ;
+
+TUPLE: flac-subframe-lpc
+    { entropy-coding-method maybe{ entropy-coding-partitioned-rice
+                                   entropy-coding-partitioned-rice2 } }
+    { qlp-coeff-precision integer }
+    { quantization-level integer }
+    { qlp-coeff integer }
+    { warmup integer }
+    residual ;
+
+TUPLE: flac-subframe-header
+    { subframe-type maybe{ subframe-type-constant
+                           subframe-type-verbatim
+                           subframe-type-fixed
+                           subframe-type-lpc } }
+    { pre-order maybe{ integer } }
+    { wasted-bits integer } ;
+
+TUPLE: flac-subframe
+    { header flac-subframe-header }
+    { data maybe{ flac-subframe-constant
+                  flac-subframe-verbatim
+                  flac-subframe-fixed
+                  flac-subframe-lpc } } ;
+
+TUPLE: flac-frame-footer
+    { crc integer } ;
+
+TUPLE: flac-frame
+    { header flac-frame-header }
+    { subframes sequence }
+    { footer flac-frame-footer } ;
+
+ENUM: metadata-type
+    metadata-stream-info
+    metadata-padding
+    metadata-application
+    metadata-seek-table
+    metadata-vorbis-comment
+    metadata-cuesheet
+    metadata-picture
+    { metadata-invalid 127 } ;
+
+
+TUPLE: metadata-block-header
+    { last? boolean }
+    { type maybe{ metadata-stream-info
+                  metadata-padding
+                  metadata-application
+                  metadata-seek-table
+                  metadata-vorbis-comment
+                  metadata-cuesheet
+                  metadata-picture
+                  metadata-invalid } }
+    { length integer } ;
+
+TUPLE: stream-info
+    { min-block-size integer }
+    { max-block-size integer }
+    { min-frame-size integer }
+    { max-frame-size integer }
+    { sample-rate integer }
+    { channels integer }
+    { bits-per-sample integer }
+    { samples integer }
+    { md5 string } ;
+
+TUPLE: seek-table
+    { seek-points array } ;
+TUPLE: seek-point
+    { sample-number integer }
+    { offset integer }
+    { total-samples } ;
+
+TUPLE: vorbis-comment
+    { vendor-string string }
+    { comments assoc } ;
+
+TUPLE: flac-padding
+    { length integer } ;
+
+TUPLE: application
+    { id string }
+    { data byte-array } ;
+
+ENUM: cuesheet-track-type audio non-audio ;
+
+TUPLE: cuesheet-track
+    { offset integer }
+    { number number }
+    { isrc string }
+    { type integer }
+    { pre-emphasis boolean }
+    { indices array } ;
+TUPLE: cuesheet-index
+    { offset integer }
+    { number integer } ;
+TUPLE: cuesheet
+    { catalog-number integer }
+    { lead-in integer }
+    { cd? boolean }
+    { tracks array } ;
+
+ENUM: picture-type
+    other
+    file-icon
+    other-file-icon
+    front-cover
+    back-cover
+    leaflet-page
+    media
+    lead-artist/performer/soloist
+    artist/performer
+    conductor
+    band/orchestra
+    composer
+    lyricist/text-writer
+    recording-location
+    during-recording
+    during-performance
+    movie/video-screen-capture
+    bright-coloured-fish
+    illustration
+    badn/artist-logotype
+    publisher/studio-logotype ;
+
+TUPLE: picture
+    type
+    { mime-type string }
+    { description string }
+    { width integer }
+    { height integer }
+    { depth integer }
+    { colors integer }
+    { data byte-array } ;
+
+TUPLE: metadata
+    { stream-info stream-info }
+    { padding maybe{ flac-padding } }
+    { application maybe{ application } }
+    { seek-table maybe{ seek-table } }
+    { vorbis-comment maybe{ vorbis-comment } }
+    { cuesheet maybe{ cuesheet } }
+    { picture maybe{ picture } } ;