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/* ##### float32encoding.js ##### | |
MIT License | |
- Forked 'toFloat' from https://gist.github.com/laerciobernardo/498f7ba1c269208799498ea8805d8c30 | |
- Forked 'toHex' from stackoverflow answer https://stackoverflow.com/a/47187116/10522253 | |
- Modifyed by: Jozo132 (https://github.com/Jozo132) | |
Permission is hereby granted, free of charge, to any person obtaining | |
a copy of this software and associated documentation files (the | |
"Software"), to deal in the Software without restriction, including | |
without limitation the rights to use, copy, modify, merge, publish, | |
distribute, sublicense, and/or sell copies of the Software, and to | |
permit persons to whom the Software is furnished to do so, subject to | |
the following conditions: | |
The above copyright notice and this permission notice shall be | |
included in all copies or substantial portions of the Software. | |
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE | |
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION | |
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION | |
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. | |
*/ | |
const Float32ToHex = (float32) => { | |
const getHex = i => ('00' + i.toString(16)).slice(-2); | |
var view = new DataView(new ArrayBuffer(4)) | |
view.setFloat32(0, float32); | |
return Array.apply(null, { length: 4 }).map((_, i) => getHex(view.getUint8(i))).join(''); | |
} | |
const Float32ToBin = (float32) => { | |
const HexToBin = hex => (parseInt(hex, 16).toString(2)).padStart(32, '0'); | |
const getHex = i => ('00' + i.toString(16)).slice(-2); | |
var view = new DataView(new ArrayBuffer(4)) | |
view.setFloat32(0, float32); | |
return HexToBin(Array.apply(null, { length: 4 }).map((_, i) => getHex(view.getUint8(i))).join('')); | |
} | |
const HexToFloat32 = (str) => { | |
var int = parseInt(str, 16); | |
if (int > 0 || int < 0) { | |
var sign = (int >>> 31) ? -1 : 1; | |
var exp = (int >>> 23 & 0xff) - 127; | |
var mantissa = ((int & 0x7fffff) + 0x800000).toString(2); | |
var float32 = 0 | |
for (i = 0; i < mantissa.length; i += 1) { float32 += parseInt(mantissa[i]) ? Math.pow(2, exp) : 0; exp-- } | |
return float32 * sign; | |
} else return 0 | |
} | |
const BinToFloat32 = (str) => { | |
var int = parseInt(str, 2); | |
if (int > 0 || int < 0) { | |
var sign = (int >>> 31) ? -1 : 1; | |
var exp = (int >>> 23 & 0xff) - 127; | |
var mantissa = ((int & 0x7fffff) + 0x800000).toString(2); | |
var float32 = 0 | |
for (i = 0; i < mantissa.length; i += 1) { float32 += parseInt(mantissa[i]) ? Math.pow(2, exp) : 0; exp-- } | |
return float32 * sign; | |
} else return 0 | |
} | |
// Full example | |
var test_value = -0.3; | |
console.log(`Input value (${test_value}) => hex (${Float32ToHex(test_value)}) [${Math.ceil(Float32ToHex(test_value).length / 2)} bytes] => float32 (${HexToFloat32(Float32ToHex(test_value))})`); | |
console.log(`Input value (${test_value}) => binary (${Float32ToBin(test_value)}) [${Float32ToBin(test_value).length} bits] => float32 (${BinToFloat32(Float32ToBin(test_value))})`); | |
/* DEBUG OUTPUT: | |
Input value (-0.3) => hex (be99999a) [4 bytes] => float32 (-0.30000001192092896) | |
Input value (-0.3) => binary (10111110100110011001100110011010) [32 bits] => float32 (-0.30000001192092896) | |
*/ |
/* ##### float32encoding.min.js ##### | |
MIT License | |
- Forked 'toFloat' from https://gist.github.com/laerciobernardo/498f7ba1c269208799498ea8805d8c30 | |
- Forked 'toHex' from stackoverflow answer https://stackoverflow.com/a/47187116/10522253 | |
- Modifyed by: Jozo132 (https://github.com/Jozo132) | |
Permission is hereby granted, free of charge, to any person obtaining | |
a copy of this software and associated documentation files (the | |
"Software"), to deal in the Software without restriction, including | |
without limitation the rights to use, copy, modify, merge, publish, | |
distribute, sublicense, and/or sell copies of the Software, and to | |
permit persons to whom the Software is furnished to do so, subject to | |
the following conditions: | |
The above copyright notice and this permission notice shall be | |
included in all copies or substantial portions of the Software. | |
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE | |
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION | |
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION | |
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. | |
*/ | |
const Float32ToHex = float32 => { const getHex = i => ('00' + i.toString(16)).slice(-2); var view = new DataView(new ArrayBuffer(4)); view.setFloat32(0, float32); return Array.apply(null, { length: 4 }).map((_, i) => getHex(view.getUint8(i))).join(''); } | |
const Float32ToBin = float32 => parseInt(Float32ToHex(float32), 16).toString(2).padStart(32, '0'); | |
const ToFloat32 = num => { if (num > 0 || num < 0) { var sign = (num >>> 31) ? -1 : 1; var exp = (num >>> 23 & 0xff) - 127; var mantissa = ((num & 0x7fffff) + 0x800000).toString(2); var float32 = 0; for (i = 0; i < mantissa.length; i += 1) { float32 += parseInt(mantissa[i]) ? Math.pow(2, exp) : 0; exp-- } return float32 * sign; } else return 0 } | |
const HexToFloat32 = str => ToFloat32(parseInt(str, 16)); | |
const BinToFloat32 = str => ToFloat32(parseInt(str, 2)); | |
// ------ FULL EXAMPLE ------ | |
var value = -0.3; // JS number variable | |
// FLOAT32 <===> HEX | |
var f32_hex = Float32ToHex(value); // JS number => HEX string of a Float32 standard number | |
var f32_hex_inverse = HexToFloat32(f32_hex); // HEX string of a Float32 standard number => JS number | |
// FLOAT32 <===> BIN | |
var f32_bin = Float32ToBin(value); // JS number => HEX string of a Float32 standard number | |
var f32_bin_inverse = BinToFloat32(f32_bin); // HEX string of a Float32 standard number => JS number | |
console.log(`Input value (${value}) => hex (${f32_hex}) [${Math.ceil(f32_hex.length / 2)} bytes] => float32 (${f32_bin_inverse})`); | |
console.log(`Input value (${value}) => binary (${f32_bin}) [${f32_bin.length} bits] => float32 (${f32_bin_inverse})`); | |
/* DEBUG OUTPUT: | |
Input value (-0.3) => hex (be99999a) [4 bytes] => float32 (-0.30000001192092896) | |
Input value (-0.3) => binary (10111110100110011001100110011010) [32 bits] => float32 (-0.30000001192092896) | |
*/ |
We know that parsing and playback of the input is possible due to code provided by the author of mkvparse
$ cat mediarecorder_pcm.xml | xml2 | grep '/mkv2xml/Segment/Cluster/SimpleBlock/data=' | cut -f2-2 -d= | xxd -r -p | ffplay -f f32le -ar 22050 -ac 1 -
That should also be possible using native code shipped with the FOSS browser. Or, conclusively determine that the conversion is not possible using code shipped with the browser.
Getting Bus error (core dumped)
at the terminal following running several un-related tests. Will probably have to re-install OS before trying to import Buffer
module. Though am trying to not use a library or import non-native modules to achieve the requirement, else could use Native Messaging.
In the browser, without using
nodejs
?
This site https://www.scadacore.com/tools/programming-calculators/online-hex-converter/ outputs the correct value for"9201c93b"
input. Yet none of the conversion formulas using JavaScript result in audio output reflecting the original file.
Could you please copy-paste the actual desired output? I'm blind here.
If "9201c93b"
is one float32 number, there can only be 11264 elements in the given array, just as I have given the answer.
Your code does in fact output the expected result.
const audioBuffer = new AudioBuffer({length: 11264, numberOfChannels: 1, sampleRate: 22050});
audioBuffer.getChannelData(0).set(new Float32Array(result));
const source = new AudioBufferSourceNode(ac, {buffer: audioBuffer});
source.connect(ac.destination);
source.start();
When new AudioContext()
is executed without specifying sampleRate
the sampleRate
is set to 44100
by default which affects the result of decodeAudioData()
. When adjusting the code to const ac = new AudioContext({sampleRate:22050, numberOfChannels:1});
both results have length
of 11264
. The AudioBufferSourceNode
created when sampleRate
is 44100
will play the AudioBuffer
which length
of 22528
.
Thanks for sharing the code and helping here.
Can you explain the purpose of the RegExp
in this part
.match(/.{1,8}/g).map(x => x.match(/.{1,2}/g).reverse().join('')
of the code?
What is the corresponding reverse of the RegExp
combinations, that is, Float32Array
to hexadecimal?
Can you explain the purpose of the
RegExp
in this part
.match(/.{1,8}/g).map(x => x.match(/.{1,2}/g).reverse().join('')
of the code?
Simply put it splits up each 8 characters for hex value of each float32 in an array, then reverses pairs for little endian decoding and puts them back together for every float32 value.
'01234567ABCDEF01' --> [ '67452301', '01EFCDAB']
So in the end you can just map every array item to the correct Float32 value
What is the corresponding reverse of the
RegExp
combinations, that is,Float32Array
to hexadecimal?
Inverse function to convert Float32Array to hex little endian buffer string is pretty simple:
let myFloatArray = [ 0.0 , 0.1 , 0.2 , 0.3 ]
let buffer_string = myFloatArray.map(f => Float32ToHex(f).match(/.{1,2}/g).reverse().join('')).join('')
Hello, this code is pretty good.
What is the license?
What is the license?
Hello, I guess we can go with MIT and keep the original head references at the top.
Is that OK?
Yes. thank you. 👍
I was thinking to be used as a simple terminal tool.
Yes. See the linked plnkr at https://gist.github.com/Jozo132/2c0fae763f5dc6635a6714bb741d152f#gistcomment-3171409. (Note, Firefox does not currently support decoding PCM in Matroska container, Chrome or Chromium needs to be used to verify results.)
All of the necessary input code is included.
The expected result is a
Float32Array
that has the same values or outputs the same or similar audio as theFloat32Array
fromgetChannelData(0)
of theAudioBuffer
created by Web Audio APIdecodeAudioData()
. That is, for the resultingFloat32Array
to be indistinguishable from theFloat32Array
fromdecodeAudioData()
as to audio output from a buffer source orAudioWorkletProcessor
(WebAudio/web-audio-api-v2#61 (comment)).