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FEAT: basic WAV codec (decoder) written directly in Rebol
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‎src/mezz/codec-wav.r

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REBOL [
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title: "REBOL 3 codec for WAV file format"
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name: 'codec-WAV
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author: "Oldes"
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version: 0.1.0
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date: 11-Oct-2018
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history: [
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0.1.0 11-Oct-2018 "Oldes" {
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Initial version with DECODE and IDENTIFY functions.
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Not all chunks are parsed.
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}
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]
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]
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register-codec [
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name: 'WAV
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title: "Waveform Audio File Format"
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suffixes: [%.wav %.wave]
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decode: function [
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data [binary!]
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][
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if verbose > 0 [
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print ["^[[1;32mDecode WAV data^[[m (^[[1m" length? data "^[[mbytes )"]
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; count maximal bytes width (used for padding)
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w: 1 + length? form length? data
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]
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bin: binary data
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binary/read bin [
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chunkId: BYTES 4
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chunkSize: UI32LE
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format: BYTES 4
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]
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if all [
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chunkId = #{52494646} ;RIFF
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format = #{57415645} ;WAVE
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][
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; looks like valid WAVE file
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data: copy []
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chunks: copy []
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while [not tail? bin/buffer][
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binary/read bin [
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id: BYTES 4
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size: UI32LE
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starts: INDEX
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]
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ends: starts + size
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chunk: any [ try [to tag! id] id ]
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if verbose > 0 [
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printf [
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$32
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"CHUNK: " $1 7 $0
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"at: " $1 w $0
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"bytes: " $1 w $0
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] reduce [mold chunk starts size]
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]
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append chunks chunk
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switch/default chunk [
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<fmt > [
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format: binary/read bin [
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UI16LE ; compression
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UI16LE ; channels
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UI32LE ; sampleRate
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UI32LE ; bytesPerSec
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UI16LE ; blockAlign
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UI16LE ; bitsPerSample
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]
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if size > 16 [
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size: size - 16
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append format copy/part bin/buffer size
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bin/buffer: skip bin/buffer size
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]
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append/only chunks format
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]
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<data> [
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binary/read/into bin [BYTES :size] tail data
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append chunks size ; so one could reconstruct the data chunk in encoding
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]
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<smpl> [
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sampler: binary/read bin [
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UI32LE ; Manufacturer
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UI32LE ; Product
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UI32LE ; Sample Period
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UI32LE ; MIDI Unity Note
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UI32LE ; MIDI Pitch Fraction
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UI32LE ; SMPTE Format
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UI32LE ; SMPTE Offset
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count: UI32LE ; Num Sample Loops
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UI32LE ; Sampler Data
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]
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append/only sampler loops: copy []
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loop count [
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binary/read/into bin [
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UI32LE ; Cue Point ID
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UI32LE ; Type
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UI32LE ; Start
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UI32LE ; End
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UI32LE ; Fraction
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UI32LE ; Play Count
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] loops
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]
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append/only chunks sampler
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]
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<fact> [
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binary/read/into bin [BYTES :size] tail chunks
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]
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<cue > [
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count: binary/read bin 'UI32LE
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append chunks cues: copy []
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loop count [
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binary/read/into bin [
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UI32LE ; id - unique identification value
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UI32LE ; Position - play order position
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UI32LE ; Data Chunk ID - RIFF ID of corresponding data chunk
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UI32LE ; Chunk Start - Byte Offset of Data Chunk *
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UI32LE ; Block Start - Byte Offset to sample of First Channel
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UI32LE ; Sample Offset - Byte Offset to sample byte of First Channel
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] tail cues
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]
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new-line/skip cues true 6
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]
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<_PMX> [
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; Extensible Metadata Platform (XMP) data
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;@@ https://www.adobe.com/products/xmp.html
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binary/read bin [tmp: BYTES :size]
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try [tmp: to string! tmp]
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append chunks tmp
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if verbose > 1 [printf [$33 tmp $0] ""]
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]
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][
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binary/read/into bin [BYTES :size] tail chunks
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]
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if ends <> index? bin/buffer [
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cause-error 'script 'bad-bad ["WAV decode" "invalid chunk end"]
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]
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]
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]
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either any [empty? chunks none? format] [
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none
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][
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new-line/skip chunks true 2
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object compose/only [
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type: 'wave
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rate: (format/3)
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channels: (format/2)
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bits: (format/6)
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chunks: (chunks)
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data: (either empty? data [none][rejoin data])
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]
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]
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]
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identify: func [
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"Returns TRUE if binary looks like WAV data"
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data [binary!]
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][
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parse data [#{52494646} 4 skip #{57415645} to end]
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]
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verbose: 0
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]

‎src/tests/run-tests.r3

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@@ -23,6 +23,7 @@ wrap load %units/conditional-test.r3
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wrap load %units/protect-test.r3
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wrap load %units/crash-test.r3
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wrap load %units/bincode-test.r3
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wrap load %units/codecs-test.r3
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recycle/torture
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recycle

‎src/tests/units/codecs-test.r3

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Rebol [
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Title: "Rebol codecs test script"
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Author: "Oldes"
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File: %codecs-test.r3
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Tabs: 4
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Needs: [%../quick-test-module.r3]
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]
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~~~start-file~~~ "Codecs"
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if find system/codecs 'wav [
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system/codecs/wav/verbose: 3
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===start-group=== "WAV codec"
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--test-- "Load WAV file"
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--assert object? snd: load %units/files/drumloop.wav
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--assert 'wave = snd/type
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--assert 44100 = snd/rate
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--assert 1 = snd/channels
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--assert 16 = snd/bits
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--assert 3097828 = checksum snd/data
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snd: none
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--test-- "Decode WAV data"
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--assert binary? bin: read %units/files/zblunk_02.wav
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--assert object? snd: decode 'WAV bin
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--assert 4283614 = checksum snd/data
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snd: none
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bin: none
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===end-group===
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system/codecs/wav/verbose: 0
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]
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~~~end-file~~~

‎src/tests/units/files/drumloop.wav

82.4 KB
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‎src/tests/units/files/zblunk_02.wav

58.8 KB
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