Unity3D script to save all frames rendered by an attached camera to png files

CaptureFrames.cs

using System;
using System.IO;
using UnityEngine;

[RequireComponent(typeof(Camera))]
public class CaptureFrames : MonoBehaviour {
	public int frameRate = 30;
	string path;
	Texture2D renderedImage;

	void Start () {
		// Save the frames in a folder named Capture/yyyy_MM_dd-HH_mm_ss/ next to the Assets 
		path = Application.dataPath;
		if (Application.isEditor) {
			path += "/../";
		}
		else if (Application.platform == RuntimePlatform.OSXPlayer) {
        	path += "/../../";
    	}
    	else if (Application.platform == RuntimePlatform.WindowsPlayer) {
        	path += "/../";
    	}
		path += "Capture/";
		if (!Directory.Exists(path)){
			Directory.CreateDirectory(path);
		}
		path += DateTime.Now.ToString("yyyy_MM_dd-HH_mm_ss/");
		if (!Directory.Exists(path)){
			Directory.CreateDirectory(path);
		}
	}
	void OnEnable () {
        // Set the playback framerate (real time will not relate to game time after this).
        Time.captureFramerate = frameRate;		
	}
	
	void OnPostRender () {
		if(renderedImage == null){
			// Create an image with the same resolution as the cameras target render texture
			Camera cam = GetComponent<Camera>();
			if(cam.targetTexture != null){
				renderedImage = new Texture2D(cam.targetTexture.width, cam.targetTexture.height);
			}
			else {
				renderedImage = new Texture2D(Screen.width, Screen.height);
			}
		}

		//read pixels from the active render texture
		renderedImage.ReadPixels(new Rect(0, 0, Screen.width, Screen.height), 0, 0);
    	renderedImage.Apply();

    	//Save image to file
    	System.IO.File.WriteAllBytes(path+Time.frameCount.ToString("000000")+".png", renderedImage.EncodeToPNG());
	}

	void OnDisable(){
		Destroy(renderedImage);
		renderedImage = null;
		Time.captureFramerate = 0;
	}
}

better:
https://github.com/keijiro/FFmpegOut