protected override string GetCommandLineArguments(EncodingJob state)
        {
            // Get the output codec name
            var videoCodec = EncodingJobFactory.GetVideoEncoder(state, GetEncodingOptions());

            var format = string.Empty;
            var keyFrame = string.Empty;

            if (string.Equals(Path.GetExtension(state.OutputFilePath), ".mp4", StringComparison.OrdinalIgnoreCase) &&
                state.Options.Context == EncodingContext.Streaming)
            {
                // Comparison: https://github.com/jansmolders86/mediacenterjs/blob/master/lib/transcoding/desktop.js
                format = " -f mp4 -movflags frag_keyframe+empty_moov";
            }

            var threads = GetNumberOfThreads(state, string.Equals(videoCodec, "libvpx", StringComparison.OrdinalIgnoreCase));

            var inputModifier = GetInputModifier(state);

            return string.Format("{0} {1}{2} {3} {4} -map_metadata -1 -threads {5} {6}{7} -y \"{8}\"",
                inputModifier,
                GetInputArgument(state),
                keyFrame,
                GetMapArgs(state),
                GetVideoArguments(state, videoCodec),
                threads,
                GetAudioArguments(state),
                format,
                state.OutputFilePath
                ).Trim();
        }

        protected override string GetOutputFileExtension(EncodingJob state)
        {
            var ext = base.GetOutputFileExtension(state);

            if (!string.IsNullOrEmpty(ext))
            {
                return ext;
            }

            var audioCodec = state.Options.AudioCodec;

            if (string.Equals("aac", audioCodec, StringComparison.OrdinalIgnoreCase))
            {
                return ".aac";
            }
            if (string.Equals("mp3", audioCodec, StringComparison.OrdinalIgnoreCase))
            {
                return ".mp3";
            }
            if (string.Equals("vorbis", audioCodec, StringComparison.OrdinalIgnoreCase))
            {
                return ".ogg";
            }
            if (string.Equals("wma", audioCodec, StringComparison.OrdinalIgnoreCase))
            {
                return ".wma";
            }

            return null;
        }

        protected override string GetCommandLineArguments(EncodingJob job)
        {
            var audioTranscodeParams = new List<string>();

            var bitrate = job.OutputAudioBitrate;

            if (bitrate.HasValue)
            {
                audioTranscodeParams.Add("-ab " + bitrate.Value.ToString(UsCulture));
            }

            if (job.OutputAudioChannels.HasValue)
            {
                audioTranscodeParams.Add("-ac " + job.OutputAudioChannels.Value.ToString(UsCulture));
            }

            if (job.OutputAudioSampleRate.HasValue)
            {
                audioTranscodeParams.Add("-ar " + job.OutputAudioSampleRate.Value.ToString(UsCulture));
            }

            var threads = GetNumberOfThreads(job, false);

            var inputModifier = GetInputModifier(job);

            return string.Format("{0} {1} -threads {2}{3} {4} -id3v2_version 3 -write_id3v1 1 -y \"{5}\"",
                inputModifier,
                GetInputArgument(job),
                threads,
                " -vn",
                string.Join(" ", audioTranscodeParams.ToArray()),
                job.OutputFilePath).Trim();
        }

        protected override Task<string> GetCommandLineArguments(EncodingJob state)
        {
            var audioTranscodeParams = new List<string>();

            var bitrate = state.OutputAudioBitrate;

            if (bitrate.HasValue)
            {
                audioTranscodeParams.Add("-ab " + bitrate.Value.ToString(UsCulture));
            }

            if (state.OutputAudioChannels.HasValue)
            {
                audioTranscodeParams.Add("-ac " + state.OutputAudioChannels.Value.ToString(UsCulture));
            }

            // opus will fail on 44100
            if (!string.Equals(state.OutputAudioCodec, "opus", StringComparison.OrdinalIgnoreCase))
            {
                if (state.OutputAudioSampleRate.HasValue)
                {
                    audioTranscodeParams.Add("-ar " + state.OutputAudioSampleRate.Value.ToString(UsCulture));
                }
            }

            var threads = GetNumberOfThreads(state, false);

            var inputModifier = GetInputModifier(state);

            var albumCoverInput = string.Empty;
            var mapArgs = string.Empty;
            var metadata = string.Empty;
            var vn = string.Empty;

            if (!string.IsNullOrWhiteSpace(state.AlbumCoverPath))
            {
                albumCoverInput = " -i \"" + state.AlbumCoverPath + "\"";
                mapArgs = " -map 0:a -map 1:v -c:v copy";
                metadata = " -metadata:s:v title=\"Album cover\" -metadata:s:v comment=\"Cover(Front)\"";
            }
            else
            {
                vn = " -vn";
            }

            var result = string.Format("{0} {1}{6}{7} -threads {2}{3} {4} -id3v2_version 3 -write_id3v1 1{8} -y \"{5}\"",
                inputModifier,
                GetInputArgument(state),
                threads,
                vn,
                string.Join(" ", audioTranscodeParams.ToArray()),
                state.OutputFilePath,
                albumCoverInput,
                mapArgs,
                metadata).Trim();

            return Task.FromResult(result);
        }

        /// <summary>
        /// Gets video arguments to pass to ffmpeg
        /// </summary>
        /// <param name="state">The state.</param>
        /// <param name="videoCodec">The video codec.</param>
        /// <returns>System.String.</returns>
        private string GetVideoArguments(EncodingJob state, string videoCodec)
        {
            var args = "-codec:v:0 " + videoCodec;

            if (state.EnableMpegtsM2TsMode)
            {
                args += " -mpegts_m2ts_mode 1";
            }

            var isOutputMkv = string.Equals(state.Options.OutputContainer, "mkv", StringComparison.OrdinalIgnoreCase);

            if (state.RunTimeTicks.HasValue)
            {
                //args += " -copyts -avoid_negative_ts disabled -start_at_zero";
            }

            if (string.Equals(videoCodec, "copy", StringComparison.OrdinalIgnoreCase))
            {
                if (state.VideoStream != null && IsH264(state.VideoStream) &&
                    (string.Equals(state.Options.OutputContainer, "ts", StringComparison.OrdinalIgnoreCase) || isOutputMkv))
                {
                    args += " -bsf:v h264_mp4toannexb";
                }

                return args;
            }

            var keyFrameArg = string.Format(" -force_key_frames expr:gte(t,n_forced*{0})",
                5.ToString(UsCulture));

            args += keyFrameArg;

            var hasGraphicalSubs = state.SubtitleStream != null && !state.SubtitleStream.IsTextSubtitleStream;

            // Add resolution params, if specified
            if (!hasGraphicalSubs)
            {
                args += GetOutputSizeParam(state, videoCodec);
            }

            var qualityParam = GetVideoQualityParam(state, videoCodec);

            if (!string.IsNullOrEmpty(qualityParam))
            {
                args += " " + qualityParam.Trim();
            }

            // This is for internal graphical subs
            if (hasGraphicalSubs)
            {
                args += GetGraphicalSubtitleParam(state, videoCodec);
            }

            return args;
        }

        /// <summary>
        /// Gets video arguments to pass to ffmpeg
        /// </summary>
        /// <param name="state">The state.</param>
        /// <param name="codec">The video codec.</param>
        /// <returns>System.String.</returns>
        private string GetVideoArguments(EncodingJob state, string codec)
        {
            var args = "-codec:v:0 " + codec;

            if (state.EnableMpegtsM2TsMode)
            {
                args += " -mpegts_m2ts_mode 1";
            }

            // See if we can save come cpu cycles by avoiding encoding
            if (string.Equals(codec, "copy", StringComparison.OrdinalIgnoreCase))
            {
                return state.VideoStream != null && IsH264(state.VideoStream) && string.Equals(state.Options.OutputContainer, "ts", StringComparison.OrdinalIgnoreCase) ?
                    args + " -bsf:v h264_mp4toannexb" :
                    args;
            }

            if (state.Options.Context == EncodingContext.Streaming)
            {
                var keyFrameArg = string.Format(" -force_key_frames expr:gte(t,n_forced*{0})",
                    5.ToString(UsCulture));

                args += keyFrameArg;
            }

            var hasGraphicalSubs = state.SubtitleStream != null && !state.SubtitleStream.IsTextSubtitleStream;

            // Add resolution params, if specified
            if (!hasGraphicalSubs)
            {
                args += GetOutputSizeParam(state, codec);
            }

            var qualityParam = GetVideoQualityParam(state, codec, false);

            if (!string.IsNullOrEmpty(qualityParam))
            {
                args += " " + qualityParam.Trim();
            }

            // This is for internal graphical subs
            if (hasGraphicalSubs)
            {
                args += GetGraphicalSubtitleParam(state, codec);
            }

            return args;
        }

        public async void StartStreamingLog(EncodingJob transcodingJob, Stream source, Stream target)
        {
            try
            {
                using (var reader = new StreamReader(source))
                {
                    while (!reader.EndOfStream)
                    {
                        var line = await reader.ReadLineAsync().ConfigureAwait(false);

                        ParseLogLine(line, transcodingJob);

                        var bytes = Encoding.UTF8.GetBytes(Environment.NewLine + line);

                        await target.WriteAsync(bytes, 0, bytes.Length).ConfigureAwait(false);
                    }
                }
            }
            catch (Exception ex)
            {
                _logger.ErrorException("Error reading ffmpeg log", ex);
            }
        }

        protected string GetVideoBitrateParam(EncodingJob state, string videoCodec, bool isHls)
        {
            var bitrate = state.OutputVideoBitrate;

            if (bitrate.HasValue)
            {
                var hasFixedResolution = state.Options.HasFixedResolution;

                if (string.Equals(videoCodec, "libvpx", StringComparison.OrdinalIgnoreCase))
                {
                    if (hasFixedResolution)
                    {
                        return string.Format(" -minrate:v ({0}*.90) -maxrate:v ({0}*1.10) -bufsize:v {0} -b:v {0}", bitrate.Value.ToString(UsCulture));
                    }

                    // With vpx when crf is used, b:v becomes a max rate
                    // https://trac.ffmpeg.org/wiki/vpxEncodingGuide. But higher bitrate source files -b:v causes judder so limite the bitrate but dont allow it to "saturate" the bitrate. So dont contrain it down just up.
                    return string.Format(" -maxrate:v {0} -bufsize:v ({0}*2) -b:v {0}", bitrate.Value.ToString(UsCulture));
                }

                if (string.Equals(videoCodec, "msmpeg4", StringComparison.OrdinalIgnoreCase))
                {
                    return string.Format(" -b:v {0}", bitrate.Value.ToString(UsCulture));
                }

                // H264
                if (hasFixedResolution)
                {
                    if (isHls)
                    {
                        return string.Format(" -b:v {0} -maxrate ({0}*.80) -bufsize {0}", bitrate.Value.ToString(UsCulture));
                    }

                    return string.Format(" -b:v {0}", bitrate.Value.ToString(UsCulture));
                }

                return string.Format(" -maxrate {0} -bufsize {1}",
                    bitrate.Value.ToString(UsCulture),
                    (bitrate.Value * 2).ToString(UsCulture));
            }

            return string.Empty;
        }

        /// <summary>
        /// Enforces the resolution limit.
        /// </summary>
        /// <param name="state">The state.</param>
        /// <param name="videoRequest">The video request.</param>
        private static void EnforceResolutionLimit(EncodingJob state, EncodingJobOptions videoRequest)
        {
            // Switch the incoming params to be ceilings rather than fixed values
            videoRequest.MaxWidth = videoRequest.MaxWidth ?? videoRequest.Width;
            videoRequest.MaxHeight = videoRequest.MaxHeight ?? videoRequest.Height;

            videoRequest.Width = null;
            videoRequest.Height = null;
        }

        internal static void TryStreamCopy(EncodingJob state,
            EncodingJobOptions videoRequest)
        {
            if (state.IsVideoRequest)
            {
                if (state.VideoStream != null && CanStreamCopyVideo(videoRequest, state.VideoStream))
                {
                    state.OutputVideoCodec = "copy";
                }

                if (state.AudioStream != null && CanStreamCopyAudio(videoRequest, state.AudioStream, state.SupportedAudioCodecs))
                {
                    state.OutputAudioCodec = "copy";
                }
            }
        }

        /// <summary>
        /// Gets the text subtitle param.
        /// </summary>
        /// <param name="state">The state.</param>
        /// <returns>System.String.</returns>
        protected string GetTextSubtitleParam(EncodingJob state)
        {
            var seconds = Math.Round(TimeSpan.FromTicks(state.Options.StartTimeTicks ?? 0).TotalSeconds);

            if (state.SubtitleStream.IsExternal)
            {
                var subtitlePath = state.SubtitleStream.Path;

                var charsetParam = string.Empty;

                if (!string.IsNullOrEmpty(state.SubtitleStream.Language))
                {
                    var charenc = SubtitleEncoder.GetSubtitleFileCharacterSet(subtitlePath, state.MediaSource.Protocol, CancellationToken.None).Result;

                    if (!string.IsNullOrEmpty(charenc))
                    {
                        charsetParam = ":charenc=" + charenc;
                    }
                }

                // TODO: Perhaps also use original_size=1920x800 ??
                return string.Format("subtitles=filename='{0}'{1},setpts=PTS -{2}/TB",
                    MediaEncoder.EscapeSubtitleFilterPath(subtitlePath),
                    charsetParam,
                    seconds.ToString(UsCulture));
            }

            return string.Format("subtitles='{0}:si={1}',setpts=PTS -{2}/TB",
                MediaEncoder.EscapeSubtitleFilterPath(state.MediaPath),
                state.InternalSubtitleStreamOffset.ToString(UsCulture),
                seconds.ToString(UsCulture));
        }

        /// <summary>
        /// Gets the map args.
        /// </summary>
        /// <param name="state">The state.</param>
        /// <returns>System.String.</returns>
        protected virtual string GetMapArgs(EncodingJob state)
        {
            // If we don't have known media info
            // If input is video, use -sn to drop subtitles
            // Otherwise just return empty
            if (state.VideoStream == null && state.AudioStream == null)
            {
                return state.IsInputVideo ? "-sn" : string.Empty;
            }

            // We have media info, but we don't know the stream indexes
            if (state.VideoStream != null && state.VideoStream.Index == -1)
            {
                return "-sn";
            }

            // We have media info, but we don't know the stream indexes
            if (state.AudioStream != null && state.AudioStream.Index == -1)
            {
                return state.IsInputVideo ? "-sn" : string.Empty;
            }

            var args = string.Empty;

            if (state.VideoStream != null)
            {
                args += string.Format("-map 0:{0}", state.VideoStream.Index);
            }
            else
            {
                args += "-map -0:v";
            }

            if (state.AudioStream != null)
            {
                args += string.Format(" -map 0:{0}", state.AudioStream.Index);
            }

            else
            {
                args += " -map -0:a";
            }

            if (state.SubtitleStream == null)
            {
                args += " -map -0:s";
            }
            else if (state.SubtitleStream.IsExternal && !state.SubtitleStream.IsTextSubtitleStream)
            {
                args += " -map 1:0 -sn";
            }

            return args;
        }

        /// <summary>
        /// Gets the video bitrate to specify on the command line
        /// </summary>
        /// <param name="state">The state.</param>
        /// <param name="videoCodec">The video codec.</param>
        /// <param name="isHls">if set to <c>true</c> [is HLS].</param>
        /// <returns>System.String.</returns>
        protected string GetVideoQualityParam(EncodingJob state, string videoCodec, bool isHls)
        {
            var param = string.Empty;

            var isVc1 = state.VideoStream != null &&
                string.Equals(state.VideoStream.Codec, "vc1", StringComparison.OrdinalIgnoreCase);

            if (string.Equals(videoCodec, "libx264", StringComparison.OrdinalIgnoreCase))
            {
                param = "-preset superfast";

                param += " -crf 28";
            }

            else if (string.Equals(videoCodec, "libx265", StringComparison.OrdinalIgnoreCase))
            {
                param = "-preset fast";

                param += " -crf 28";
            }

            // webm
            else if (string.Equals(videoCodec, "libvpx", StringComparison.OrdinalIgnoreCase))
            {
                // Values 0-3, 0 being highest quality but slower
                var profileScore = 0;

                string crf;
                var qmin = "0";
                var qmax = "50";

                crf = "10";

                if (isVc1)
                {
                    profileScore++;
                }

                // Max of 2
                profileScore = Math.Min(profileScore, 2);

                // http://www.webmproject.org/docs/encoder-parameters/
                param = string.Format("-speed 16 -quality good -profile:v {0} -slices 8 -crf {1} -qmin {2} -qmax {3}",
                    profileScore.ToString(UsCulture),
                    crf,
                    qmin,
                    qmax);
            }

            else if (string.Equals(videoCodec, "mpeg4", StringComparison.OrdinalIgnoreCase))
            {
                param = "-mbd rd -flags +mv4+aic -trellis 2 -cmp 2 -subcmp 2 -bf 2";
            }

            // asf/wmv
            else if (string.Equals(videoCodec, "wmv2", StringComparison.OrdinalIgnoreCase))
            {
                param = "-qmin 2";
            }

            else if (string.Equals(videoCodec, "msmpeg4", StringComparison.OrdinalIgnoreCase))
            {
                param = "-mbd 2";
            }

            param += GetVideoBitrateParam(state, videoCodec, isHls);

            var framerate = GetFramerateParam(state);
            if (framerate.HasValue)
            {
                param += string.Format(" -r {0}", framerate.Value.ToString(UsCulture));
            }

            if (!string.IsNullOrEmpty(state.OutputVideoSync))
            {
                param += " -vsync " + state.OutputVideoSync;
            }

            if (!string.IsNullOrEmpty(state.Options.Profile))
            {
                param += " -profile:v " + state.Options.Profile;
            }

            if (state.Options.Level.HasValue)
            {
                param += " -level " + state.Options.Level.Value.ToString(UsCulture);
            }

            return "-pix_fmt yuv420p " + param;
        }

 /// <summary>
 /// Gets the number of threads.
 /// </summary>
 /// <returns>System.Int32.</returns>
 protected int GetNumberOfThreads(EncodingJob job, bool isWebm)
 {
     return job.Options.CpuCoreLimit ?? 0;
 }

        protected virtual string GetOutputFileExtension(EncodingJob state)
        {
            if (!string.IsNullOrWhiteSpace(state.Options.OutputContainer))
            {
                return "." + state.Options.OutputContainer;
            }

            return null;
        }

 private void AttachMediaStreamInfo(EncodingJob state,
   MediaSourceInfo mediaSource,
   EncodingJobOptions videoRequest)
 {
     EncodingJobFactory.AttachMediaStreamInfo(state, mediaSource, videoRequest);
 }

        /// <summary>
        /// Gets the internal graphical subtitle param.
        /// </summary>
        /// <param name="state">The state.</param>
        /// <param name="outputVideoCodec">The output video codec.</param>
        /// <returns>System.String.</returns>
        protected string GetGraphicalSubtitleParam(EncodingJob state, string outputVideoCodec)
        {
            var outputSizeParam = string.Empty;

            var request = state.Options;

            // Add resolution params, if specified
            if (request.Width.HasValue || request.Height.HasValue || request.MaxHeight.HasValue || request.MaxWidth.HasValue)
            {
                outputSizeParam = GetOutputSizeParam(state, outputVideoCodec).TrimEnd('"');
                outputSizeParam = "," + outputSizeParam.Substring(outputSizeParam.IndexOf("scale", StringComparison.OrdinalIgnoreCase));
            }

            var videoSizeParam = string.Empty;

            if (state.VideoStream != null && state.VideoStream.Width.HasValue && state.VideoStream.Height.HasValue)
            {
                videoSizeParam = string.Format(",scale={0}:{1}", state.VideoStream.Width.Value.ToString(UsCulture), state.VideoStream.Height.Value.ToString(UsCulture));
            }

            var mapPrefix = state.SubtitleStream.IsExternal ?
                1 :
                0;

            var subtitleStreamIndex = state.SubtitleStream.IsExternal
                ? 0
                : state.SubtitleStream.Index;

            return string.Format(" -filter_complex \"[{0}:{1}]format=yuva444p{4},lut=u=128:v=128:y=gammaval(.3)[sub] ; [0:{2}] [sub] overlay{3}\"",
                mapPrefix.ToString(UsCulture),
                subtitleStreamIndex.ToString(UsCulture),
                state.VideoStream.Index.ToString(UsCulture),
                outputSizeParam,
                videoSizeParam);
        }

        protected string GetInputModifier(EncodingJob job, bool genPts = true)
        {
            var inputModifier = string.Empty;

            var probeSize = GetProbeSizeArgument(job);
            inputModifier += " " + probeSize;
            inputModifier = inputModifier.Trim();

            var userAgentParam = GetUserAgentParam(job);

            if (!string.IsNullOrWhiteSpace(userAgentParam))
            {
                inputModifier += " " + userAgentParam;
            }

            inputModifier = inputModifier.Trim();

            inputModifier += " " + GetFastSeekCommandLineParameter(job.Options);
            inputModifier = inputModifier.Trim();

            if (job.IsVideoRequest && genPts)
            {
                inputModifier += " -fflags +genpts";
            }

            if (!string.IsNullOrEmpty(job.InputAudioSync))
            {
                inputModifier += " -async " + job.InputAudioSync;
            }

            if (!string.IsNullOrEmpty(job.InputVideoSync))
            {
                inputModifier += " -vsync " + job.InputVideoSync;
            }

            if (job.ReadInputAtNativeFramerate)
            {
                inputModifier += " -re";
            }

            var videoDecoder = GetVideoDecoder(job);
            if (!string.IsNullOrWhiteSpace(videoDecoder))
            {
                inputModifier += " " + videoDecoder;
            }

            return inputModifier;
        }

        protected double? GetFramerateParam(EncodingJob state)
        {
            if (state.Options.Framerate.HasValue)
            {
                return state.Options.Framerate.Value;
            }

            var maxrate = state.Options.MaxFramerate;

            if (maxrate.HasValue && state.VideoStream != null)
            {
                var contentRate = state.VideoStream.AverageFrameRate ?? state.VideoStream.RealFrameRate;

                if (contentRate.HasValue && contentRate.Value > maxrate.Value)
                {
                    return maxrate;
                }
            }

            return null;
        }

        /// <summary>
        /// Gets the name of the output video codec
        /// </summary>
        /// <param name="state">The state.</param>
        /// <returns>System.String.</returns>
        protected string GetVideoDecoder(EncodingJob state)
        {
            if (string.Equals(GetEncodingOptions().HardwareVideoDecoder, "qsv", StringComparison.OrdinalIgnoreCase))
            {
                if (state.VideoStream != null && !string.IsNullOrWhiteSpace(state.VideoStream.Codec))
                {
                    switch (state.MediaSource.VideoStream.Codec.ToLower())
                    {
                        case "avc":
                        case "h264":
                            if (MediaEncoder.SupportsDecoder("h264_qsv"))
                            {
                                return "-c:v h264_qsv ";
                            }
                            break;
                        case "mpeg2video":
                            if (MediaEncoder.SupportsDecoder("mpeg2_qsv"))
                            {
                                return "-c:v mpeg2_qsv ";
                            }
                            break;
                        case "vc1":
                            if (MediaEncoder.SupportsDecoder("vc1_qsv"))
                            {
                                return "-c:v vc1_qsv ";
                            }
                            break;
                    }
                }
            }

            // leave blank so ffmpeg will decide
            return null;
        }