Waveform.cs

using UnityEngine;

public class Waveform : MonoBehaviour
{
	private Material material;
	private float[] samples;

	private void Start()
	{
		material = GetComponent<Renderer>().material;
		samples = new float[1024];
	}

	private void Update()
    {
		for (int i = 0; i < samples.Length; i++)
			samples[i] = Mathf.Sin(Time.time + i * 1f) / 2 + 0.5f;
		material.SetFloatArray("_samples", samples);
    }
}

Waveform.shader

Shader "Unlit/Waveform"
{
    Properties
    {
    }
    SubShader
    {
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            v2f vert(appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

			float _samples[1024];

            fixed4 frag(v2f i) : SV_Target
            {
				float s = _samples[(int)i.uv.x * 1024];
				if (abs(i.uv.y - s) < 0.01f)
					return fixed4(1, 1, 1, 1);
				else
					return fixed4(0, 0, 0, 1);
            }
            ENDCG
        }
    }
}