FFMpegCore/FFMpegCore/FFMpeg/Arguments/DemuxConcatArgument.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace FFMpegCore.Arguments
{
    /// <summary>
    /// Represents parameter of concat argument
    /// Used for creating video from multiple images or videos
    /// </summary>
    public class DemuxConcatArgument : IInputArgument
    {
        public readonly IEnumerable<string> Values;
        public DemuxConcatArgument(IEnumerable<string> values)
        {
            Values = values.Select(value => $"file '{Escape(value)}'");
        }

        /// <summary>
        /// Thanks slhck
        /// https://superuser.com/a/787651/1089628
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        private string Escape(string value) => value.Replace("'", @"'\''");
        
        private readonly string _tempFileName = Path.Combine(GlobalFFOptions.Current.TemporaryFilesFolder, $"concat_{Guid.NewGuid()}.txt");

        public void Pre() => File.WriteAllLines(_tempFileName, Values);
        public Task During(CancellationToken cancellationToken = default) => Task.CompletedTask;
        public void Post() => File.Delete(_tempFileName);

        public string Text => $"-f concat -safe 0 -i \"{_tempFileName}\"";
    }
}