How NOT to Sample Audio! - Computerphile

Could Dave recreate audio from a wav file preview image grabbed from a screen cap?

More about David Domminney Fowler: https://youtube.com/c/DavidDomminneyFowler

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This video was filmed and edited by Sean Riley.

Computer Science at the University of Nottingham: https://bit.ly/nottscomputer

Computerphile is a sister project to Brady Haran's Numberphile. More at http://www.bradyharan.com

Original Image: https://photos.app.goo.gl/c4pPY8xpCF6cNmTF8

Dave's Code:
(angle brackets weren't allowed in YT description)
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Extract_Audio
{
internal class Program
{
private static void Main(string[] args)
{
string file = "computerphile.png";

Bitmap b = new Bitmap(@"g:\Computerphile\" + file);

var values = new System.Collections.Generic.ListANGLEBRACKETOPENintANGLEBRACKETCLOSE();

for (int x = 0; x ANGLEBRACKETOPEN b.Width; x++)
{
int max = 0;
int min = b.Height;

for (int y = 0; y ANGLEBRACKETOPEN b.Height; y++)
{
if (b.GetPixel(x, y).GetBrightness() ANGLEBRACKETCLOSE 0.5)
{
min = Math.Min(y, min);
max = Math.Max(max, y);
}
}

values.Add(min);
values.Add(max);
}

int filter = 4;

for (int x = 0; x ANGLEBRACKETOPEN values.Count - filter; x++)
values[x] = (int)values.GetRange(x, filter).Average();

var f = new System.IO.StreamWriter($@"g:\Computerphile\{file}.txt");

foreach (var v in values)
f.WriteLine(v);

f.Close();

var wf = System.IO.File.OpenWrite($@"g:\Computerphile\{file}.wav");

var RIFF_HEADER = new byte[] { 0x52, 0x49, 0x46, 0x46 };
var FORMAT_WAVE = new byte[] { 0x57, 0x41, 0x56, 0x45 };
var FORMAT_TAG = new byte[] { 0x66, 0x6D, 0x74, 0x20 };
var AUDIO_FORMAT = new byte[] { 0x1, 0x0 };
var SUBCHUNK_ID = new byte[] { 0x64, 0x61, 0x74, 0x61 };
int BYTES_PER_SAMPLE = 1;
int samplerate = 48000;
int channelcount = 1;
int lastv2 = 0;
int stretch = 9;
int datalength = values.Count * stretch * BYTES_PER_SAMPLE;
int byteRate = samplerate * channelcount * BYTES_PER_SAMPLE;
int blockAlign = channelcount * BYTES_PER_SAMPLE;

wf.Write(RIFF_HEADER, 0, RIFF_HEADER.Length);
wf.Write(BitConverter.GetBytes(datalength + 40), 0, 4);
wf.Write(FORMAT_WAVE, 0, FORMAT_WAVE.Length);
wf.Write(FORMAT_TAG, 0, FORMAT_TAG.Length);
wf.Write(BitConverter.GetBytes(16), 0, 4);
wf.Write(AUDIO_FORMAT, 0, AUDIO_FORMAT.Length);
wf.Write(BitConverter.GetBytes(channelcount), 0, 2);
wf.Write(BitConverter.GetBytes(samplerate), 0, 4);
wf.Write(BitConverter.GetBytes(byteRate), 0, 4);
wf.Write(BitConverter.GetBytes(blockAlign), 0, 2);
wf.Write(BitConverter.GetBytes(BYTES_PER_SAMPLE * 8), 0, 2);
wf.Write(SUBCHUNK_ID, 0, SUBCHUNK_ID.Length);
wf.Write(BitConverter.GetBytes(datalength), 0, 4);

foreach (var v in values)
{
double v2 = (v - values.Min()) / (double)(values.Max() - values.Min()) * 255;

for (int x = 0; x ANGLEBRACKETOPEN stretch; x++)
{
double v3 = x / (double)stretch * v2 + (1 - x / (double)stretch) * lastv2;
wf.WriteByte(Convert.ToByte(v3));
}

lastv2 = (int)v2;
}

wf.Close();
}
}
}

Видео How NOT to Sample Audio! - Computerphile канала Computerphile