C# MediaProtocol类代码示例

        public static string GetInputArgument(List<string> inputFiles, MediaProtocol protocol)
        {
            if (protocol == MediaProtocol.Http)
            {
                var url = inputFiles.First();

                return string.Format("\"{0}\"", url);
            }
            if (protocol == MediaProtocol.Rtmp)
            {
                var url = inputFiles.First();

                return string.Format("\"{0}\"", url);
            }
            if (protocol == MediaProtocol.Rtsp)
            {
                var url = inputFiles.First();

                return string.Format("\"{0}\"", url);
            }
            if (protocol == MediaProtocol.Udp)
            {
                var url = inputFiles.First();

                return string.Format("\"{0}\"", url);
            }

            return GetConcatInputArgument(inputFiles);
        }

        /// <summary>
        /// Gets the input argument.
        /// </summary>
        /// <param name="fileSystem">The file system.</param>
        /// <param name="videoPath">The video path.</param>
        /// <param name="protocol">The protocol.</param>
        /// <param name="isoMount">The iso mount.</param>
        /// <param name="playableStreamFileNames">The playable stream file names.</param>
        /// <returns>System.String[][].</returns>
        public static string[] GetInputArgument(IFileSystem fileSystem, string videoPath, MediaProtocol protocol, IIsoMount isoMount, List<string> playableStreamFileNames)
        {
            if (playableStreamFileNames.Count > 0)
            {
                if (isoMount == null)
                {
                    return GetPlayableStreamFiles(fileSystem, videoPath, playableStreamFileNames).ToArray();
                }
                return GetPlayableStreamFiles(fileSystem, isoMount.MountedPath, playableStreamFileNames).ToArray();
            }

            return new[] {videoPath};
        }

        /// <summary>
        /// Gets the probe size argument.
        /// </summary>
        /// <param name="inputFiles">The input files.</param>
        /// <param name="protocol">The protocol.</param>
        /// <returns>System.String.</returns>
        public string GetProbeSizeAndAnalyzeDurationArgument(string[] inputFiles, MediaProtocol protocol)
        {
            var results = new List<string>();

            var probeSize = EncodingUtils.GetProbeSizeArgument(inputFiles.Length);
            var analyzeDuration = EncodingUtils.GetAnalyzeDurationArgument(inputFiles.Length);

            if (!string.IsNullOrWhiteSpace(probeSize))
            {
                results.Add(probeSize);
            }

            if (!string.IsNullOrWhiteSpace(analyzeDuration))
            {
                results.Add(analyzeDuration);
            }
            return string.Join(" ", results.ToArray());
        }

        private async Task<Stream> ExtractImageInternal(string inputPath, MediaProtocol protocol, Video3DFormat? threedFormat, TimeSpan? offset, bool useIFrame, SemaphoreSlim resourcePool, CancellationToken cancellationToken)
        {
            if (string.IsNullOrEmpty(inputPath))
            {
                throw new ArgumentNullException("inputPath");
            }

            // apply some filters to thumbnail extracted below (below) crop any black lines that we made and get the correct ar then scale to width 600. 
            // This filter chain may have adverse effects on recorded tv thumbnails if ar changes during presentation ex. commercials @ diff ar
            var vf = "scale=600:trunc(600/dar/2)*2";

            if (threedFormat.HasValue)
            {
                switch (threedFormat.Value)
                {
                    case Video3DFormat.HalfSideBySide:
                        vf = "crop=iw/2:ih:0:0,scale=(iw*2):ih,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1,scale=600:trunc(600/dar/2)*2";
                        // hsbs crop width in half,scale to correct size, set the display aspect,crop out any black bars we may have made the scale width to 600. Work out the correct height based on the display aspect it will maintain the aspect where -1 in this case (3d) may not.
                        break;
                    case Video3DFormat.FullSideBySide:
                        vf = "crop=iw/2:ih:0:0,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1,scale=600:trunc(600/dar/2)*2";
                        //fsbs crop width in half,set the display aspect,crop out any black bars we may have made the scale width to 600.
                        break;
                    case Video3DFormat.HalfTopAndBottom:
                        vf = "crop=iw:ih/2:0:0,scale=(iw*2):ih),setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1,scale=600:trunc(600/dar/2)*2";
                        //htab crop heigh in half,scale to correct size, set the display aspect,crop out any black bars we may have made the scale width to 600
                        break;
                    case Video3DFormat.FullTopAndBottom:
                        vf = "crop=iw:ih/2:0:0,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1,scale=600:trunc(600/dar/2)*2";
                        // ftab crop heigt in half, set the display aspect,crop out any black bars we may have made the scale width to 600
                        break;
                }
            }

            // TODO: Output in webp for smaller sizes
            // -f image2 -f webp

            // Use ffmpeg to sample 100 (we can drop this if required using thumbnail=50 for 50 frames) frames and pick the best thumbnail. Have a fall back just in case.
            var args = useIFrame ? string.Format("-i {0} -threads 0 -v quiet -vframes 1 -vf \"{2},thumbnail=30\" -f image2 \"{1}\"", inputPath, "-", vf) :
                string.Format("-i {0} -threads 0 -v quiet -vframes 1 -vf \"{2}\" -f image2 \"{1}\"", inputPath, "-", vf);

            var probeSize = GetProbeSizeArgument(new[] { inputPath }, protocol);

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

            if (offset.HasValue)
            {
                args = string.Format("-ss {0} ", GetTimeParameter(offset.Value)) + args;
            }

            var process = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    CreateNoWindow = true,
                    UseShellExecute = false,
                    FileName = FFMpegPath,
                    Arguments = args,
                    WindowStyle = ProcessWindowStyle.Hidden,
                    ErrorDialog = false,
                    RedirectStandardOutput = true,
                    RedirectStandardError = true,
                    RedirectStandardInput = true
                }
            };

            await resourcePool.WaitAsync(cancellationToken).ConfigureAwait(false);

            process.Start();

            var memoryStream = new MemoryStream();

#pragma warning disable 4014
            // Important - don't await the log task or we won't be able to kill ffmpeg when the user stops playback
            process.StandardOutput.BaseStream.CopyToAsync(memoryStream);
#pragma warning restore 4014

            // MUST read both stdout and stderr asynchronously or a deadlock may occurr
            process.BeginErrorReadLine();

            var ranToCompletion = process.WaitForExit(10000);

            if (!ranToCompletion)
            {
                try
                {
                    _logger.Info("Killing ffmpeg process");

                    process.StandardInput.WriteLine("q");

                    process.WaitForExit(1000);
                }
                catch (Exception ex)
                {
                    _logger.ErrorException("Error killing process", ex);
                }
            }
//.........这里部分代码省略.........

 public Task<Stream> ExtractVideoImage(string[] inputFiles, MediaProtocol protocol, Video3DFormat? threedFormat,
     TimeSpan? offset, CancellationToken cancellationToken)
 {
     return ExtractImage(inputFiles, protocol, false, threedFormat, offset, cancellationToken);
 }

 /// <summary>
 /// Gets the input argument.
 /// </summary>
 /// <param name="inputFiles">The input files.</param>
 /// <param name="protocol">The protocol.</param>
 /// <returns>System.String.</returns>
 /// <exception cref="System.ArgumentException">Unrecognized InputType</exception>
 public string GetInputArgument(string[] inputFiles, MediaProtocol protocol)
 {
     return EncodingUtils.GetInputArgument(inputFiles.ToList(), protocol);
 }

        public async Task ExtractVideoImagesOnInterval(string[] inputFiles,
            MediaProtocol protocol,
            Video3DFormat? threedFormat,
            TimeSpan interval,
            string targetDirectory,
            string filenamePrefix,
            int? maxWidth,
            CancellationToken cancellationToken)
        {
            var resourcePool = _thumbnailResourcePool;

            var inputArgument = GetInputArgument(inputFiles, protocol);

            var vf = "fps=fps=1/" + interval.TotalSeconds.ToString(UsCulture);

            if (maxWidth.HasValue)
            {
                var maxWidthParam = maxWidth.Value.ToString(UsCulture);

                vf += string.Format(",scale=min(iw\\,{0}):trunc(ow/dar/2)*2", maxWidthParam);
            }

            FileSystem.CreateDirectory(targetDirectory);
            var outputPath = Path.Combine(targetDirectory, filenamePrefix + "%05d.jpg");

            var args = string.Format("-i {0} -threads 1 -v quiet -vf \"{2}\" -f image2 \"{1}\"", inputArgument, outputPath, vf);

            var probeSize = GetProbeSizeArgument(new[] { inputArgument }, protocol);

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

            var process = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    CreateNoWindow = true,
                    UseShellExecute = false,
                    FileName = FFMpegPath,
                    Arguments = args,
                    WindowStyle = ProcessWindowStyle.Hidden,
                    ErrorDialog = false,
                    RedirectStandardInput = true
                }
            };

            _logger.Info(process.StartInfo.FileName + " " + process.StartInfo.Arguments);

            await resourcePool.WaitAsync(cancellationToken).ConfigureAwait(false);

            bool ranToCompletion = false;

            using (var processWrapper = new ProcessWrapper(process, this, _logger))
            {
                try
                {
                    StartProcess(processWrapper);

                    // Need to give ffmpeg enough time to make all the thumbnails, which could be a while,
                    // but we still need to detect if the process hangs.
                    // Making the assumption that as long as new jpegs are showing up, everything is good.

                    bool isResponsive = true;
                    int lastCount = 0;

                    while (isResponsive)
                    {
                        if (process.WaitForExit(30000))
                        {
                            ranToCompletion = true;
                            break;
                        }

                        cancellationToken.ThrowIfCancellationRequested();

                        var jpegCount = Directory.GetFiles(targetDirectory)
                            .Count(i => string.Equals(Path.GetExtension(i), ".jpg", StringComparison.OrdinalIgnoreCase));

                        isResponsive = (jpegCount > lastCount);
                        lastCount = jpegCount;
                    }

                    if (!ranToCompletion)
                    {
                        StopProcess(processWrapper, 1000, false);
                    }
                }
                finally
                {
                    resourcePool.Release();
                }

                var exitCode = ranToCompletion ? processWrapper.ExitCode ?? 0 : -1;

                if (exitCode == -1)
                {
                    var msg = string.Format("ffmpeg image extraction failed for {0}", inputArgument);

//.........这里部分代码省略.........

        /// <summary>
        /// Gets the media info internal.
        /// </summary>
        /// <param name="inputPath">The input path.</param>
        /// <param name="primaryPath">The primary path.</param>
        /// <param name="protocol">The protocol.</param>
        /// <param name="extractChapters">if set to <c>true</c> [extract chapters].</param>
        /// <param name="probeSizeArgument">The probe size argument.</param>
        /// <param name="isAudio">if set to <c>true</c> [is audio].</param>
        /// <param name="videoType">Type of the video.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task{MediaInfoResult}.</returns>
        /// <exception cref="System.ApplicationException">ffprobe failed - streams and format are both null.</exception>
        private async Task<Model.MediaInfo.MediaInfo> GetMediaInfoInternal(string inputPath,
            string primaryPath,
            MediaProtocol protocol,
            bool extractChapters,
            string probeSizeArgument,
            bool isAudio,
            VideoType videoType,
            CancellationToken cancellationToken)
        {
            var args = extractChapters
                ? "{0} -i {1} -threads 0 -v info -print_format json -show_streams -show_chapters -show_format"
                : "{0} -i {1} -threads 0 -v info -print_format json -show_streams -show_format";

            var process = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    CreateNoWindow = true,
                    UseShellExecute = false,

                    // Must consume both or ffmpeg may hang due to deadlocks. See comments below.   
                    RedirectStandardOutput = true,
                    RedirectStandardError = true,
                    RedirectStandardInput = true,
                    FileName = FFProbePath,
                    Arguments = string.Format(args,
                    probeSizeArgument, inputPath).Trim(),

                    WindowStyle = ProcessWindowStyle.Hidden,
                    ErrorDialog = false
                },

                EnableRaisingEvents = true
            };

            _logger.Debug("{0} {1}", process.StartInfo.FileName, process.StartInfo.Arguments);

            using (var processWrapper = new ProcessWrapper(process, this, _logger))
            {
                await _ffProbeResourcePool.WaitAsync(cancellationToken).ConfigureAwait(false);

                try
                {
                    StartProcess(processWrapper);
                }
                catch (Exception ex)
                {
                    _ffProbeResourcePool.Release();

                    _logger.ErrorException("Error starting ffprobe", ex);

                    throw;
                }

                try
                {
                    process.BeginErrorReadLine();

                    var result = _jsonSerializer.DeserializeFromStream<InternalMediaInfoResult>(process.StandardOutput.BaseStream);

                    if (result.streams == null && result.format == null)
                    {
                        throw new ApplicationException("ffprobe failed - streams and format are both null.");
                    }

                    if (result.streams != null)
                    {
                        // Normalize aspect ratio if invalid
                        foreach (var stream in result.streams)
                        {
                            if (string.Equals(stream.display_aspect_ratio, "0:1", StringComparison.OrdinalIgnoreCase))
                            {
                                stream.display_aspect_ratio = string.Empty;
                            }
                            if (string.Equals(stream.sample_aspect_ratio, "0:1", StringComparison.OrdinalIgnoreCase))
                            {
                                stream.sample_aspect_ratio = string.Empty;
                            }
                        }
                    }

                    var mediaInfo = new ProbeResultNormalizer(_logger, FileSystem).GetMediaInfo(result, videoType, isAudio, primaryPath, protocol);

                    var videoStream = mediaInfo.MediaStreams.FirstOrDefault(i => i.Type == MediaStreamType.Video);

                    if (videoStream != null)
                    {
//.........这里部分代码省略.........

        private async Task<string> ExtractImageInternal(string inputPath, int? imageStreamIndex, MediaProtocol protocol, Video3DFormat? threedFormat, TimeSpan? offset, bool useIFrame, SemaphoreSlim resourcePool, CancellationToken cancellationToken)
        {
            if (string.IsNullOrEmpty(inputPath))
            {
                throw new ArgumentNullException("inputPath");
            }

            var tempExtractPath = Path.Combine(ConfigurationManager.ApplicationPaths.TempDirectory, Guid.NewGuid() + ".jpg");
            Directory.CreateDirectory(Path.GetDirectoryName(tempExtractPath));

            // apply some filters to thumbnail extracted below (below) crop any black lines that we made and get the correct ar then scale to width 600. 
            // This filter chain may have adverse effects on recorded tv thumbnails if ar changes during presentation ex. commercials @ diff ar
            var vf = "scale=600:trunc(600/dar/2)*2";

            if (threedFormat.HasValue)
            {
                switch (threedFormat.Value)
                {
                    case Video3DFormat.HalfSideBySide:
                        vf = "crop=iw/2:ih:0:0,scale=(iw*2):ih,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1,scale=600:trunc(600/dar/2)*2";
                        // hsbs crop width in half,scale to correct size, set the display aspect,crop out any black bars we may have made the scale width to 600. Work out the correct height based on the display aspect it will maintain the aspect where -1 in this case (3d) may not.
                        break;
                    case Video3DFormat.FullSideBySide:
                        vf = "crop=iw/2:ih:0:0,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1,scale=600:trunc(600/dar/2)*2";
                        //fsbs crop width in half,set the display aspect,crop out any black bars we may have made the scale width to 600.
                        break;
                    case Video3DFormat.HalfTopAndBottom:
                        vf = "crop=iw:ih/2:0:0,scale=(iw*2):ih),setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1,scale=600:trunc(600/dar/2)*2";
                        //htab crop heigh in half,scale to correct size, set the display aspect,crop out any black bars we may have made the scale width to 600
                        break;
                    case Video3DFormat.FullTopAndBottom:
                        vf = "crop=iw:ih/2:0:0,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1,scale=600:trunc(600/dar/2)*2";
                        // ftab crop heigt in half, set the display aspect,crop out any black bars we may have made the scale width to 600
                        break;
                    default:
                        break;
                }
            }

            var mapArg = imageStreamIndex.HasValue ? (" -map 0:v:" + imageStreamIndex.Value.ToString(CultureInfo.InvariantCulture)) : string.Empty;

            // Use ffmpeg to sample 100 (we can drop this if required using thumbnail=50 for 50 frames) frames and pick the best thumbnail. Have a fall back just in case.
            var args = useIFrame ? string.Format("-i {0}{3} -threads 0 -v quiet -vframes 1 -vf \"{2},thumbnail=30\" -f image2 \"{1}\"", inputPath, tempExtractPath, vf, mapArg) :
                string.Format("-i {0}{3} -threads 0 -v quiet -vframes 1 -vf \"{2}\" -f image2 \"{1}\"", inputPath, tempExtractPath, vf, mapArg);

            var probeSize = GetProbeSizeArgument(new[] { inputPath }, protocol);

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

            if (offset.HasValue)
            {
                args = string.Format("-ss {0} ", GetTimeParameter(offset.Value)) + args;
            }

            var process = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    CreateNoWindow = true,
                    UseShellExecute = false,
                    FileName = FFMpegPath,
                    Arguments = args,
                    WindowStyle = ProcessWindowStyle.Hidden,
                    ErrorDialog = false
                }
            };

            _logger.Debug("{0} {1}", process.StartInfo.FileName, process.StartInfo.Arguments);

            using (var processWrapper = new ProcessWrapper(process, this, _logger, false))
            {
                await resourcePool.WaitAsync(cancellationToken).ConfigureAwait(false);

                bool ranToCompletion;

                try
                {
                    StartProcess(processWrapper);

                    ranToCompletion = process.WaitForExit(10000);

                    if (!ranToCompletion)
                    {
                        StopProcess(processWrapper, 1000, false);
                    }

                }
                finally
                {
                    resourcePool.Release();
                }

                var exitCode = ranToCompletion ? processWrapper.ExitCode ?? 0 : -1;
                var file = new FileInfo(tempExtractPath);

                if (exitCode == -1 || !file.Exists || file.Length == 0)
                {
//.........这里部分代码省略.........

 public Task<string> ExtractVideoImage(string[] inputFiles, MediaProtocol protocol, int? imageStreamIndex, CancellationToken cancellationToken)
 {
     return ExtractImage(inputFiles, imageStreamIndex, protocol, false, null, null, cancellationToken);
 }

        public MediaInfo GetMediaInfo(InternalMediaInfoResult data, VideoType videoType, bool isAudio, string path, MediaProtocol protocol)
        {
            var info = new MediaInfo
            {
                Path = path,
                Protocol = protocol
            };

            FFProbeHelpers.NormalizeFFProbeResult(data);
            SetSize(data, info);

            var internalStreams = data.streams ?? new MediaStreamInfo[] { };

            info.MediaStreams = internalStreams.Select(s => GetMediaStream(isAudio, s, data.format))
                .Where(i => i != null)
                .ToList();

            if (data.format != null)
            {
                info.Container = data.format.format_name;

                if (!string.IsNullOrEmpty(data.format.bit_rate))
                {
                    int value;
                    if (int.TryParse(data.format.bit_rate, NumberStyles.Any, _usCulture, out value))
                    {
                        info.Bitrate = value;
                    }
                }
            }

            var tags = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
            var tagStreamType = isAudio ? "audio" : "video";

            if (data.streams != null)
            {
                var tagStream = data.streams.FirstOrDefault(i => string.Equals(i.codec_type, tagStreamType, StringComparison.OrdinalIgnoreCase));

                if (tagStream != null && tagStream.tags != null)
                {
                    foreach (var pair in tagStream.tags)
                    {
                        tags[pair.Key] = pair.Value;
                    }
                }
            }

            if (data.format != null && data.format.tags != null)
            {
                foreach (var pair in data.format.tags)
                {
                    tags[pair.Key] = pair.Value;
                }
            }

            FetchGenres(info, tags);
            var shortOverview = FFProbeHelpers.GetDictionaryValue(tags, "description");
            var overview = FFProbeHelpers.GetDictionaryValue(tags, "synopsis");

            if (string.IsNullOrWhiteSpace(overview))
            {
                overview = shortOverview;
                shortOverview = null;
            }
            if (string.IsNullOrWhiteSpace(overview))
            {
                overview = FFProbeHelpers.GetDictionaryValue(tags, "desc");
            }

            if (!string.IsNullOrWhiteSpace(overview))
            {
                info.Overview = overview;
            }

            if (!string.IsNullOrWhiteSpace(shortOverview))
            {
                info.ShortOverview = shortOverview;
            }

            var title = FFProbeHelpers.GetDictionaryValue(tags, "title");
            if (!string.IsNullOrWhiteSpace(title))
            {
                info.Name = title;
            }

            info.ProductionYear = FFProbeHelpers.GetDictionaryNumericValue(tags, "date");

            // Several different forms of retaildate
            info.PremiereDate = FFProbeHelpers.GetDictionaryDateTime(tags, "retaildate") ??
                FFProbeHelpers.GetDictionaryDateTime(tags, "retail date") ??
                FFProbeHelpers.GetDictionaryDateTime(tags, "retail_date") ??
                FFProbeHelpers.GetDictionaryDateTime(tags, "date");

            if (isAudio)
            {
                SetAudioRuntimeTicks(data, info);

                // tags are normally located under data.format, but we've seen some cases with ogg where they're part of the info stream
                // so let's create a combined list of both

//.........这里部分代码省略.........

        /// <summary>
        /// Gets the media info internal.
        /// </summary>
        /// <param name="inputPath">The input path.</param>
        /// <param name="primaryPath">The primary path.</param>
        /// <param name="protocol">The protocol.</param>
        /// <param name="extractChapters">if set to <c>true</c> [extract chapters].</param>
        /// <param name="extractKeyFrameInterval">if set to <c>true</c> [extract key frame interval].</param>
        /// <param name="probeSizeArgument">The probe size argument.</param>
        /// <param name="isAudio">if set to <c>true</c> [is audio].</param>
        /// <param name="videoType">Type of the video.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task{MediaInfoResult}.</returns>
        /// <exception cref="System.ApplicationException"></exception>
        private async Task<Model.MediaInfo.MediaInfo> GetMediaInfoInternal(string inputPath,
            string primaryPath,
            MediaProtocol protocol,
            bool extractChapters,
            bool extractKeyFrameInterval,
            string probeSizeArgument,
            bool isAudio,
            VideoType videoType,
            CancellationToken cancellationToken)
        {
            var args = extractChapters
                ? "{0} -i {1} -threads 0 -v info -print_format json -show_streams -show_chapters -show_format"
                : "{0} -i {1} -threads 0 -v info -print_format json -show_streams -show_format";

            var process = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    CreateNoWindow = true,
                    UseShellExecute = false,

                    // Must consume both or ffmpeg may hang due to deadlocks. See comments below.   
                    RedirectStandardOutput = true,
                    RedirectStandardError = true,
                    RedirectStandardInput = true,
                    FileName = FFProbePath,
                    Arguments = string.Format(args,
                    probeSizeArgument, inputPath).Trim(),

                    WindowStyle = ProcessWindowStyle.Hidden,
                    ErrorDialog = false
                },

                EnableRaisingEvents = true
            };

            _logger.Debug("{0} {1}", process.StartInfo.FileName, process.StartInfo.Arguments);

            await _ffProbeResourcePool.WaitAsync(cancellationToken).ConfigureAwait(false);

            using (var processWrapper = new ProcessWrapper(process, this, _logger))
            {
                try
                {
                    StartProcess(processWrapper);
                }
                catch (Exception ex)
                {
                    _ffProbeResourcePool.Release();

                    _logger.ErrorException("Error starting ffprobe", ex);

                    throw;
                }

                try
                {
                    process.BeginErrorReadLine();

                    var result = _jsonSerializer.DeserializeFromStream<InternalMediaInfoResult>(process.StandardOutput.BaseStream);

                    if (result != null)
                    {
                        if (result.streams != null)
                        {
                            // Normalize aspect ratio if invalid
                            foreach (var stream in result.streams)
                            {
                                if (string.Equals(stream.display_aspect_ratio, "0:1", StringComparison.OrdinalIgnoreCase))
                                {
                                    stream.display_aspect_ratio = string.Empty;
                                }
                                if (string.Equals(stream.sample_aspect_ratio, "0:1", StringComparison.OrdinalIgnoreCase))
                                {
                                    stream.sample_aspect_ratio = string.Empty;
                                }
                            }
                        }

                        var mediaInfo = new ProbeResultNormalizer(_logger, FileSystem).GetMediaInfo(result, videoType, isAudio, primaryPath, protocol);

                        if (extractKeyFrameInterval && mediaInfo.RunTimeTicks.HasValue)
                        {
                            if (ConfigurationManager.Configuration.EnableVideoFrameAnalysis && mediaInfo.Size.HasValue && mediaInfo.Size.Value <= ConfigurationManager.Configuration.VideoFrameAnalysisLimitBytes)
                            {
                                foreach (var stream in mediaInfo.MediaStreams)
//.........这里部分代码省略.........

        private async Task<Tuple<string, string>> GetReadableFile(string mediaPath,
            string[] inputFiles,
            MediaProtocol protocol,
            MediaStream subtitleStream,
            CancellationToken cancellationToken)
        {
            if (!subtitleStream.IsExternal)
            {
                // Extract    
                var outputPath = GetSubtitleCachePath(mediaPath, subtitleStream.Index, ".ass");

                await ExtractTextSubtitle(inputFiles, protocol, subtitleStream.Index, false, outputPath, cancellationToken)
                        .ConfigureAwait(false);

                return new Tuple<string, string>(outputPath, "ass");
            }

            var currentFormat = (Path.GetExtension(subtitleStream.Path) ?? subtitleStream.Codec)
                .TrimStart('.');

            if (GetReader(currentFormat, false) == null)
            {
                // Convert    
                var outputPath = GetSubtitleCachePath(mediaPath, subtitleStream.Index, ".ass");

                await ConvertTextSubtitleToAss(subtitleStream.Path, outputPath, subtitleStream.Language, cancellationToken)
                        .ConfigureAwait(false);

                return new Tuple<string, string>(outputPath, "ass");
            }

            return new Tuple<string, string>(subtitleStream.Path, currentFormat);
        }

        private async Task<string> DetectCharset(string path, MediaProtocol protocol, CancellationToken cancellationToken)
        {
            try
            {
                using (var file = await GetStream(path, protocol, cancellationToken).ConfigureAwait(false))
                {
                    var detector = new CharsetDetector();
                    detector.Feed(file);
                    detector.DataEnd();

                    var charset = detector.Charset;

                    if (!string.IsNullOrWhiteSpace(charset))
                    {
                        _logger.Info("UniversalDetector detected charset {0} for {1}", charset, path);
                    }

                    return charset;
                }
            }
            catch (IOException ex)
            {
                _logger.ErrorException("Error attempting to determine subtitle charset from {0}", ex, path);
            }

            return null;
        }

        private async Task<Stream> GetSubtitleStream(string path, MediaProtocol protocol, bool requiresCharset, CancellationToken cancellationToken)
        {
            if (requiresCharset)
            {
                var charset = await GetSubtitleFileCharacterSet(path, protocol, cancellationToken).ConfigureAwait(false);

                if (!string.IsNullOrEmpty(charset))
                {
                    using (var fs = await GetStream(path, protocol, cancellationToken).ConfigureAwait(false))
                    {
                        using (var reader = new StreamReader(fs, GetEncoding(charset)))
                        {
                            var text = await reader.ReadToEndAsync().ConfigureAwait(false);

                            var bytes = Encoding.UTF8.GetBytes(text);

                            return new MemoryStream(bytes);
                        }
                    }
                }
            }

            return _fileSystem.OpenRead(path);
        }