Real time Microphone (line input) FFT analysis

this is the answer I've currently got going. would have posted as a comment, but couldn't post this much code.

ah, hmm. i'm trying to get down as close to real time as possible for the purposes of music visualization. i realize unity isn't really built for that, so i'm kinda trying to just work with what I can.

using this code, I've got down to about 50 milliseconds, but there's a bit of a stutter every time the buffer switches. but in this case the audio only needs to be analyzed, not actually heard, but it does seem to choke the game in that moment.

This is the entire script I created to make this happen. I haven't revisited it to make it cleaner, just set it up to work.

Also, if you're looking for non-realtime audio analysis (e.g. running audio analysis on saved audio files that are playing back), this script works well with very little latency

 using UnityEngine;
 using System.Collections;
 
 
 public class FFT : MonoBehaviour
 {
     
     #region vars
     public string CurrentAudioInput;
     
     private AudioObj[] audioObj = new AudioObj[2];
     
     private const int BANDS = 4;
     
     //public float[] curve = new float[BANDS]; //scale output of band analysis
     public float[] output = new float[BANDS];
     
     public string[] inputDevices;
     private int[] crossovers = new int[BANDS];
     private float[] freqData = new float[8192];
     private float[] band;
     
     public GameObject playerPrefab;
     private int index = 0;
     
     public static FFT Instance;
     private bool doSound = true;
     private int deviceNum;
     
     
     private struct AudioObj
     {
         public GameObject player;
         public AudioClip clip;
         public void SetClip(AudioClip c)
         {
             clip = c;
             player.audio.clip = c;
             /*
     slowing the playback down a small amount allows enough space between
     recording and output so that analysis does not overtake the recording.
     this helps with stutter and distortion, but doesn't solve it completely
     */
             player.audio.pitch = .95f;
         }
     }
     #endregion
     
     #region Unity Methods
     void Start()
     {
         Instance = this;
         
         crossovers[0] = 30; //guesstimating sample lengths for frequency bands
         crossovers[1] = 50;
         crossovers[2] = 600;
         crossovers[3] = freqData.Length;
         
         band = new float[BANDS];
         output = new float[BANDS];
         
         for (int i = 0; i < audioObj.Length; i++)
         {
             audioObj[i].player = (GameObject)Instantiate(playerPrefab);
             audioObj[i].player.transform.parent = transform;
             audioObj[i].player.transform.position = Vector3.zero;
             audioObj[i].clip = new AudioClip();
         }
         
         inputDevices = new string[Microphone.devices.Length];
         deviceNum = Microphone.devices.Length - 1;
         
         for (int i = 0; i < Microphone.devices.Length; i++)
             inputDevices[i] = Microphone.devices[i].ToString();
         
         CurrentAudioInput = Microphone.devices[deviceNum].ToString();
         
         InvokeRepeating("Check", 0, 1.0f / 15.0f);
         StartCoroutine(StartRecord());
         
     }
     
     void Update()
     {
         KeyInput();
     }
     #endregion
     
     #region Actions
     
     private void Check()
     {
         if (!doSound)
             return;
         
         audioObj[index].player.audio.GetSpectrumData(freqData, 0, FFTWindow.Hamming);
     
         bool cutoff = false;
         int k = 0;
         float[] lengths = new float[BANDS];
         for(int i = 0; i < BANDS; i++)
         {
             float min = (i > 0 ? crossovers[i-1] : 0);
             lengths[i] = crossovers[i] - min; 
             band[i] = 0f;
         }
         
         for (int i = 0; i < freqData.Length; i++)
         {
             
             if (k > BANDS - 1)
                 break;
             
             band[k] += freqData[i];
             if(i > crossovers[k])
             {
                 output[k] = Mathf.Abs(band[k] / lengths[k]);
                 k++;
             }
             if (i > crossovers[BANDS - 1] - 10)
                 cutoff = true;
         }
     }
     
     private IEnumerator StartRecord()
     {
         
         audioObj[index].clip = Microphone.Start(Microphone.devices[deviceNum], true, 5, 24000);
         /*
     the longer the mic recording time, the less often there are "hiccups" in game performance
     but also due to being pitched down, the playback gradually falls farther behind the recording
     */
         
         print("recording to audioObj " + index);
         StartCoroutine(StartPlay(audioObj[index].clip));
         yield return new WaitForSeconds(5);
         StartCoroutine(StartRecord()); //swaps audio buffers, begins recording and playback of new buffer
         /* it is necessary to swap buffers, otherwise the audioclip quickly becomes too large and begins to slow down the system */
         
     }
     
     private IEnumerator StartPlay(AudioClip buffer)
     {
         audioObj[index].SetClip(buffer);
         yield return new WaitForSeconds(.01f);
         audioObj[index].player.SetActive(true);
         audioObj[index].player.audio.Play();
         
         audioObj[Mathf.Abs((index % 2) - 1)].player.audio.Stop();
         
         index++;
         if (index > 1)
             index = 0;
         
         
     }
     
     private void KeyInput()
     {
         if (Input.GetKeyDown(KeyCode.A))
         {
             doSound = !doSound;
         }
         if (Input.GetKeyDown(KeyCode.Equals))
         {
             deviceNum++;
             if (deviceNum > Microphone.devices.Length - 1)
                 deviceNum = 0;
             CurrentAudioInput = Microphone.devices[deviceNum].ToString();
         }
     }
     #endregion
     
     
 }