quality-control/Assets/Scripts/ConveyorBelt.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ConveyorBelt : MonoBehaviour
{
    Rigidbody _rb;
    Rigidbody rb { get { if (!_rb) _rb = GetComponent<Rigidbody>(); return _rb; } }

    public float speed = 1;

    Vector3 startPosition;

    float scrollingTextureProgress = 0;
    public float scrollingTextureSpeedMult = 1;
    public Renderer scrollingTextureRenderer;

    public AudioSource audioSource;
    
    private void Start()
    {
        float length = audioSource.clip.length;
        audioSource.time += Random.Range(0.2f * length, 0.4f * length);
        audioSource.pitch = Random.Range(-0.05f, 0.05f) + speed / 2f;
        
        startPosition = rb.position;
    }

    private void FixedUpdate()
    {
        rb.position = startPosition;
        Vector3 targetSpeed = speed * transform.forward;
        rb.MovePosition(rb.position + targetSpeed * Time.deltaTime);
    }

    private void Update()
    {
        if(scrollingTextureRenderer)
        {
            scrollingTextureProgress += Time.deltaTime * speed * scrollingTextureSpeedMult;
            scrollingTextureRenderer.material.SetTextureOffset("_MainTex", 
                new Vector2(0, scrollingTextureProgress));
        }
    }
}