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@@ -265,11 +265,24 @@ namespace WinFormsApp3
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}
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/// <summary>
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/// 用 ffmpeg 把 DASH 视频轨和音频轨合并成 mp4（直接 copy 不重编码）。
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/// 用 ffmpeg 把 DASH 视频轨和音频轨合并成 mp4。
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/// 优先两条流直接 copy：不重编码、时间戳原样保留，音画对齐最准确；
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/// 只有音频轨格式装不进 mp4 容器时才回退到 AAC 转码。
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/// </summary>
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private static async Task<bool> MuxDashAsync(string ffmpeg, string videoFile, string audioFile, string outputFile, CancellationToken ct)
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{
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var args = $"-hide_banner -loglevel error -y -i \"{videoFile}\" -i \"{audioFile}\" -c:v copy -c:a aac -strict experimental -movflags +faststart \"{outputFile}\"";
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// 只取视频轨的视频流 + 音频轨的音频流（没音频流也照常出片），-shortest 把两条轨截齐到同一时长
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var copyArgs = $"-hide_banner -loglevel error -y -fflags +genpts -i \"{videoFile}\" -i \"{audioFile}\" -map 0:v:0 -map 1:a:0? -c copy -shortest -movflags +faststart \"{outputFile}\"";
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if (await RunFfmpegAsync(ffmpeg, copyArgs, outputFile, ct)) return true;
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TryDelete(outputFile);
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var aacArgs = $"-hide_banner -loglevel error -y -fflags +genpts -i \"{videoFile}\" -i \"{audioFile}\" -map 0:v:0 -map 1:a:0? -c:v copy -c:a aac -strict experimental -shortest -movflags +faststart \"{outputFile}\"";
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return await RunFfmpegAsync(ffmpeg, aacArgs, outputFile, ct);
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}
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private static async Task<bool> RunFfmpegAsync(string ffmpeg, string args, string outputFile, CancellationToken ct)
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{
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var psi = new ProcessStartInfo
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{
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FileName = ffmpeg,
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@@ -291,6 +304,170 @@ namespace WinFormsApp3
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return proc.ExitCode == 0 && File.Exists(outputFile) && new FileInfo(outputFile).Length > 0;
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}
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/// <summary>
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/// 抽帧结果：成功时 Frames 非空；失败时 Error 给界面显示原因，不让用户干等。
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/// </summary>
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public record FrameExtraction(List<byte[]> Frames, string? Error);
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/// <summary>
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/// 抽取预览截图：每 intervalSeconds 秒取一张、共取 frameCount 张（默认 5 秒 3 张），
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/// 供下载列表肉眼对比哪个是当前视频。用 ffmpeg 直接读远端地址，带 Referer/Cookie 过防盗链。
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/// 单次尝试限 25 秒，超时不再重试第二次，避免地址失效时列表长时间卡在“生成中”。
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/// </summary>
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public async Task<FrameExtraction> ExtractFramesAsync(string url, CancellationToken ct, int intervalSeconds = 5, int frameCount = 3)
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{
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var ffmpeg = FindFfmpeg();
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if (ffmpeg == null)
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{
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return new FrameExtraction(new List<byte[]>(), "未找到 ffmpeg，无法生成截图");
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}
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if (!Uri.TryCreate(url, UriKind.Absolute, out var uri)
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|| (uri.Scheme != Uri.UriSchemeHttp && uri.Scheme != Uri.UriSchemeHttps))
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{
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return new FrameExtraction(new List<byte[]>(), "该地址无法直接抽帧");
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}
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var tmpDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
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Directory.CreateDirectory(tmpDir);
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try
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{
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string? lastError = null;
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// 先试从第 2 秒开始抽（片头常有黑帧），只有上一次正常退出且没拿到帧才退回 0 秒再试
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foreach (var startAt in new[] { 2, 0 })
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{
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ct.ThrowIfCancellationRequested();
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var args = new List<string>
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{
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"-hide_banner", "-loglevel", "error", "-nostdin", "-y",
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// 远端卡住时快速失败：单次 I/O 12 秒，探测上限 2MB/2秒，不靠外部杀进程兑底
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"-rw_timeout", "12000000",
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"-probesize", "2000000", "-analyzeduration", "2000000",
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"-reconnect", "1", "-reconnect_streamed", "1", "-reconnect_delay_max", "2"
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};
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var headers = BuildFfmpegHeaders();
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if (headers.Length > 0)
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{
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args.Add("-headers");
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args.Add(headers);
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}
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if (IsHlsUrl(url))
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{
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args.Add("-protocol_whitelist");
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args.Add("file,http,https,tcp,tls,crypto");
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}
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args.AddRange(new[]
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{
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"-ss", startAt.ToString(), "-i", url,
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"-t", (intervalSeconds * frameCount).ToString(),
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"-vf", $"fps=1/{intervalSeconds},scale=160:-2",
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"-frames:v", frameCount.ToString(), "-an",
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Path.Combine(tmpDir, "f_%d.jpg")
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});
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var run = await RunFfmpegArgsAsync(ffmpeg, args, ct);
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var files = Directory.GetFiles(tmpDir, "f_*.jpg").OrderBy(f => f, StringComparer.Ordinal).ToList();
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if (files.Count > 0)
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{
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return new FrameExtraction(files.Select(File.ReadAllBytes).ToList(), null);
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}
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lastError = run.Error ?? "没抽到帧";
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if (run.TimedOut)
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{
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break; // 地址多半已失效或被防盗链卡住，再试一次只会多等半分钟
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}
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}
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return new FrameExtraction(new List<byte[]>(), lastError ?? "没抽到帧");
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}
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finally
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{
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try { Directory.Delete(tmpDir, true); } catch { /* 临时目录删不掉不影响结果 */ }
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}
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}
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/// <summary>
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/// ffmpeg 走网络也要过防盗链：把下载器身上的 UA / Referer / Cookie 拼成 -headers 参数。
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/// </summary>
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private string BuildFfmpegHeaders()
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{
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var sb = new StringBuilder();
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sb.Append($"User-Agent: {UserAgent}\r\n");
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if (_referer != null) sb.Append($"Referer: {_referer}\r\n");
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if (_cookie != null) sb.Append($"Cookie: {_cookie}\r\n");
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return sb.ToString();
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}
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/// <summary>ffmpeg 单次运行结果：TimedOut 表示被外部杀掉，Error 给界面显示原因。</summary>
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private record FfmpegRun(bool TimedOut, string? Error);
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private static async Task<FfmpegRun> RunFfmpegArgsAsync(string ffmpeg, List<string> args, CancellationToken ct)
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{
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var psi = new ProcessStartInfo
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{
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FileName = ffmpeg,
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UseShellExecute = false,
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CreateNoWindow = true,
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RedirectStandardError = true,
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RedirectStandardOutput = true
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};
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foreach (var a in args) psi.ArgumentList.Add(a);
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using var proc = Process.Start(psi);
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if (proc == null) return new FfmpegRun(false, "ffmpeg 启动失败");
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// 就算 -rw_timeout 失效（DNS 卡住、TLS 握手挂起等），25 秒也必须杀掉
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using var timeout = CancellationTokenSource.CreateLinkedTokenSource(ct);
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timeout.CancelAfter(TimeSpan.FromSeconds(25));
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var errRead = proc.StandardError.ReadToEndAsync(); // 不读干 stderr 会把进程堵死
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bool timedOut = false;
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using (timeout.Token.Register(() => { try { if (!proc.HasExited) proc.Kill(true); } catch { } }))
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{
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try
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{
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await proc.WaitForExitAsync(timeout.Token);
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}
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catch (OperationCanceledException) when (ct.IsCancellationRequested)
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{
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throw; // 用户取消要往上抛，超时杀掉进程则返回原因
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}
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catch (OperationCanceledException)
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{
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timedOut = true;
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}
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}
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string stderr = string.Empty;
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try { stderr = await errRead; } catch { /* 进程被杀时读流可能报错，不影响判断 */ }
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if (timedOut)
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{
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return new FfmpegRun(true, "抽帧超时（25秒）：地址可能已失效或被防盗链卡住");
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}
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if (proc.ExitCode != 0)
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{
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return new FfmpegRun(false, SummarizeFfmpegError(stderr));
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}
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return new FfmpegRun(false, null);
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}
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/// <summary>取 ffmpeg 报错里最有信息量的一行，太长截断，直接丢给界面显示。</summary>
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private static string SummarizeFfmpegError(string stderr)
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{
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var line = (stderr ?? string.Empty)
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.Split('\n')
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.Select(l => l.Trim('\r', ' '))
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.FirstOrDefault(l => l.Length > 0 && !l.StartsWith("[h264", StringComparison.OrdinalIgnoreCase)
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&& !l.StartsWith("[aac", StringComparison.OrdinalIgnoreCase));
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if (string.IsNullOrEmpty(line)) return "ffmpeg 抽帧失败";
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return line.Length > 90 ? line[..90] + "…" : line;
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}
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private HttpClient CreateClient()
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{
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var client = new HttpClient(new HttpClientHandler { AllowAutoRedirect = false })
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