Use pipes in c# to pull a specific frame (time) from ffmpeg into a texture in unity. SLOW.

FfmpegPipe.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Diagnostics;
using System.IO;
using System;

//	stolen from https://github.com/keijiro/FFmpegOut/blob/master/Assets/FFmpegOut/FFmpegPipe.cs
//	then gave up and wrote from scratch




public static class FfmpegPipe
{
	const string ffmpeg_exe = "/usr/local/bin/ffmpeg";

	public static byte[] BlockReadVideoFrameBytes(string InputFilename, int TimeMs,int? OutputWidth,int? OutputHeight,bool ShowProgressBars)
	{
		//	00:00:07.100	but can specify seconds
		var TimeSecs = TimeMs / 1000.0f;
		var TimeSecsString = TimeSecs.ToString("F3");

		var ScaleString = "";
		if (OutputWidth.HasValue || OutputHeight.HasValue)
		{
			if (!OutputWidth.HasValue) OutputWidth = -1;
			if (!OutputHeight.HasValue) OutputHeight = -1;
			ScaleString = "-vf scale=" + OutputWidth.Value + ":" + OutputHeight.Value;
		}


		var CommandLineArgs = "";

		CommandLineArgs += " -i " + InputFilename;
		CommandLineArgs += " " + ScaleString;
		CommandLineArgs += " -ss " + TimeSecsString;
		CommandLineArgs += " -vframes 1";
		CommandLineArgs += " -f image2pipe pipe:1";


		var info = new ProcessStartInfo(ffmpeg_exe, CommandLineArgs);
		info.UseShellExecute = false;
		info.CreateNoWindow = false;
		info.RedirectStandardInput = false;
		info.RedirectStandardOutput = true;
		info.RedirectStandardError = false;

		var SubProcess = Process.Start(info);

		System.Action<BinaryReader, List<Byte>> ReadAllStream = (BinaryStream,AllBuffer) =>
		{
			while (true)
			{
				var Buffer = new byte[1024*10];
				int BytesRead = BinaryStream.Read(Buffer, 0, Buffer.Length);
				//	add the whole buffer, then remove the tail chunk
				AllBuffer.AddRange(Buffer);
				var Cull = Buffer.Length - BytesRead;
				AllBuffer.RemoveRange(AllBuffer.Count - Cull, Cull);
				if (BytesRead == 0)
					break;
			}
		};

		var OutBuffer = new List<byte>();
		//var ErrBuffer = new List<byte>();
		var StdoutReader = new BinaryReader(SubProcess.StandardOutput.BaseStream);
		//var StderrReader = new BinaryReader(SubProcess.StandardError.BaseStream);

		//	run until done
		try
		{
			using (var Progress = new ScopedProgressBar("Running ffmpeg " + CommandLineArgs,ShowProgressBars))
			{
				while (!SubProcess.HasExited)
				{
					ReadAllStream(StdoutReader, OutBuffer);
				//	ReadAllStream(StderrReader, ErrBuffer);
				//	UnityEngine.Debug.Log("Waiting for ffmpeg...");
					System.Threading.Thread.Sleep(1);

					//	was trying to get progress bar to wake up so we could cancel. no effect
					//UnityEditor.EditorApplication.QueuePlayerLoopUpdate();
				}
			}
		}
		catch(System.Exception e)
		{
			UnityEngine.Debug.LogException(e);
			SubProcess.Kill();
			throw;
		}
		/*


		var OutBuffer = ReadAllStream(StdoutReader);
		//var ErrBuffer = ReadAllStream(StderrReader);
		var ErrorOutput = SubProcess.StandardError.ReadToEnd();

		//Debug.Log("Output " + OutBuffer.Count + " bytes, error " + ErrBuffer.Count + " bytes");
		UnityEngine.Debug.Log("Output " + OutBuffer.Count + " bytes, error=" + ErrorOutput);
*/
		SubProcess.Close();
		SubProcess.Dispose();

		//outputReader.Close();
		//outputReader.Dispose();
		return OutBuffer.ToArray();
	}

	public static Texture2D BlockReadVideoFrame(string InputFilename, int TimeMs,int? OutputWidth, int? OutputHeight,bool ShowProgressBars)
	{
		//	image2pipe only comes out as jpeg apparently
		var JpegBytes = BlockReadVideoFrameBytes(InputFilename, TimeMs, OutputWidth, OutputHeight, ShowProgressBars );
		var Texture = new Texture2D(1, 1);

		using (var Progress = new ScopedProgressBar("Converting to jpeg... (x" + JpegBytes.Length + " bytes)",ShowProgressBars))
		{
			if (!Texture.LoadImage(JpegBytes))
				throw new System.Exception("Failed to load jpegbytes(x" + JpegBytes.Length + ") into texture");
			Texture.Apply();
		}
		return Texture;
	}

}