196 lines
9.1 KiB
C#
196 lines
9.1 KiB
C#
using System.Globalization;
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using System.Xml.Linq;
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namespace VideoDownloader.Core.Dash;
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/// <summary>
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/// MPD(DASH 매니페스트) 파서. 클리어(비DRM) 콘텐츠의 최고화질 비디오(+오디오) 트랙을 구성.
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/// 지원: SegmentTemplate($Number$/SegmentTimeline/duration) + SegmentList + BaseURL 누적.
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/// 미지원: DRM(ContentProtection), SegmentBase(바이트레인지), 다중 Period.
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/// 네임스페이스 무관(LocalName 기반 조회).
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/// </summary>
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public static class DashParser
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{
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public static DashManifest? Parse(string xml, Uri mpdUrl, bool lowestRep = false)
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{
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XDocument doc;
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try { doc = XDocument.Parse(xml); }
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catch { return null; }
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var mpd = doc.Root;
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if (mpd == null || mpd.Name.LocalName != "MPD") return null;
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var period = Child(mpd, "Period");
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if (period == null || Child(period, "ContentProtection") != null) return null; // DRM
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var mpdBase = Combine(mpdUrl, Val(Child(mpd, "BaseURL")));
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var periodBase = Combine(mpdBase, Val(Child(period, "BaseURL")));
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// 세그먼트 수 산정용 기간: Period@duration > MPD@mediaPresentationDuration > MPD@duration
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var periodSec = ParseDuration(Attr(period, "duration"));
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if (periodSec <= 0) periodSec = ParseDuration(Attr(mpd, "mediaPresentationDuration"));
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if (periodSec <= 0) periodSec = ParseDuration(Attr(mpd, "duration"));
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DashTrack? video = null, audio = null;
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foreach (var s in Children(period, "AdaptationSet"))
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{
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if (Child(s, "ContentProtection") != null) continue; // DRM 셋
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var ct = (Attr(s, "contentType") ?? Attr(s, "mimeType") ?? "").ToLowerInvariant();
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var track = BuildTrack(s, periodSec, periodBase, lowestRep);
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if (track == null) continue;
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if (video == null && ct.Contains("video")) video = track;
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else if (audio == null && ct.Contains("audio")) audio = track;
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else if (video == null) video = track; // contentType 없으면 첫 트랙을 비디오로
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}
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if (video == null) return null;
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return new DashManifest { Video = video, Audio = audio, DurationSec = periodSec };
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}
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/// <summary>하나의 AdaptationSet 에서 최고(또는 최저)화질 비DRM 표현을 골라 세그먼트 묶음 생성.</summary>
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private static DashTrack? BuildTrack(XElement set, double periodSec, Uri periodBase, bool lowestRep)
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{
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var setBase = Combine(periodBase, Val(Child(set, "BaseURL")));
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var setTemplate = Child(set, "SegmentTemplate");
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XElement? rep = null; long bestBw = -1;
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foreach (var r in Children(set, "Representation"))
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{
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if (Child(r, "ContentProtection") != null) continue;
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var bw = (long?)r.Attribute("bandwidth") ?? 0;
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if (rep == null || (lowestRep ? bw < bestBw : bw > bestBw)) { bestBw = bw; rep = r; }
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}
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if (rep == null) return null;
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var repBase = Combine(setBase, Val(Child(rep, "BaseURL")));
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var tmpl = Child(rep, "SegmentTemplate") ?? setTemplate;
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var repId = Attr(rep, "id") ?? "0";
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var bwStr = bestBw.ToString();
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// SegmentList
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var segList = Child(rep, "SegmentList") ?? Child(set, "SegmentList");
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if (segList != null)
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{
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var segs = new List<DashSegment>(); int i = 0;
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foreach (var su in Children(segList, "SegmentURL"))
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{
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var m = Attr(su, "media");
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if (m != null) segs.Add(new DashSegment(Combine(repBase, m), i++));
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}
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var init = Attr(segList, "initialization");
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return new DashTrack { InitUrl = init != null ? Combine(repBase, init) : null, Segments = segs };
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}
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// SegmentTemplate
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if (tmpl != null)
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{
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var initT = Attr(tmpl, "initialization");
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var mediaT = Attr(tmpl, "media");
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if (string.IsNullOrEmpty(mediaT)) return null;
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var startNumber = (long?)tmpl.Attribute("startNumber") ?? 1;
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var tmplBase = Combine(repBase, Val(Child(tmpl, "BaseURL")));
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Uri? initUrl = initT != null ? Combine(tmplBase, Subst(initT, repId, bwStr, startNumber, 0)) : null;
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var segs = new List<DashSegment>();
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var timeline = Child(tmpl, "SegmentTimeline");
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if (timeline != null)
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{
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// #8 $Time$ 는 미디어 시작시간(t/d 누적) 이지 세그먼트 번호가 아님(ISO/IEC 23009-1).
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// t 속성은 타임라인을 해당 절대시각으로 재설정.
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// #9 r=-1 은 "Period 끝까지 반복" — count=r+1=0 으로 0개를 내던 버그 수정.
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var timescale = (long?)tmpl.Attribute("timescale") ?? 1;
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long endTime = periodSec > 0 ? (long)Math.Ceiling(periodSec * timescale) : long.MaxValue;
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long number = startNumber; int idx = 0; long time = 0;
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const long MaxSegs = 200000; // 폭주 방지 상한
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foreach (var se in Children(timeline, "S"))
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{
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var tAttr = (long?)se.Attribute("t");
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if (tAttr.HasValue) time = tAttr.Value; // t: 타임라인 재설정(절대 시각)
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var d = (long?)se.Attribute("d") ?? 0;
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var r = (long?)se.Attribute("r") ?? 0;
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if (d <= 0) continue;
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if (r < 0)
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{
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// r=-1: 다음 세그먼트 시작이 Period 끝(endTime) 에 달하거나 넘으면 정지.
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while (idx < MaxSegs && time < endTime)
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{
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segs.Add(new DashSegment(Combine(tmplBase, Subst(mediaT, repId, bwStr, number, time)), idx++));
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number++; time += d;
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}
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}
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else
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{
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for (long k = 0; k < r + 1 && idx < MaxSegs; k++)
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{
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segs.Add(new DashSegment(Combine(tmplBase, Subst(mediaT, repId, bwStr, number, time)), idx++));
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number++; time += d;
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}
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}
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}
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}
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else
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{
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var timescale = (long?)tmpl.Attribute("timescale") ?? 1;
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var duration = (long?)tmpl.Attribute("duration") ?? 0;
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if (duration > 0)
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{
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long total = periodSec > 0 ? (long)Math.Ceiling(periodSec * timescale / (double)duration) : 0;
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if (total <= 0) total = 1;
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for (long n = 0; n < total; n++)
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segs.Add(new DashSegment(Combine(tmplBase, Subst(mediaT, repId, bwStr, startNumber + n, n * duration)), (int)n));
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}
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}
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return new DashTrack { InitUrl = initUrl, Segments = segs };
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}
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// BaseURL 단일 파일 표현
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var repBaseOnly = Val(Child(rep, "BaseURL"));
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if (!string.IsNullOrEmpty(repBaseOnly))
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return new DashTrack { InitUrl = null, Segments = new[] { new DashSegment(Combine(setBase, repBaseOnly), 0) } };
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return null;
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}
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private static XElement? Child(XElement? p, string local) =>
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p?.Elements().FirstOrDefault(e => e.Name.LocalName == local);
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private static IEnumerable<XElement> Children(XElement? p, string local) =>
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p?.Elements().Where(e => e.Name.LocalName == local) ?? Enumerable.Empty<XElement>();
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private static string? Attr(XElement e, string n) => (string?)e.Attribute(n);
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private static string? Val(XElement? e) => e == null ? null : e.Value.Trim();
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/// <param name="number">$Number$ 값(세그먼트 순번)</param>
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/// <param name="time">$Time$ 값(미디어 시작시각, SegmentTimeline 누적 t/d 또는 n*duration)</param>
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private static string Subst(string template, string repId, string bw, long number, long time)
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=> template.Replace("$RepresentationID$", repId)
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.Replace("$Bandwidth$", bw)
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.Replace("$Number$", number.ToString())
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.Replace("$Time$", time.ToString());
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private static Uri Combine(Uri? baseUri, string? rel)
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{
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if (string.IsNullOrEmpty(rel)) return baseUri!;
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if (Uri.IsWellFormedUriString(rel, UriKind.Absolute)) return new Uri(rel);
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if (baseUri == null) return new Uri(rel, UriKind.Relative);
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return new Uri(baseUri, rel);
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}
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private static double ParseDuration(string? d)
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{
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if (string.IsNullOrEmpty(d)) return 0;
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var s = d.Trim();
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if (!s.StartsWith("PT", StringComparison.OrdinalIgnoreCase)) return 0;
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s = s.Substring(2);
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double total = 0; var num = "";
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foreach (var ch in s)
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{
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if (char.IsDigit(ch) || ch == '.') num += ch;
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else if (ch is 'H' or 'M' or 'S' && double.TryParse(num, NumberStyles.Any, CultureInfo.InvariantCulture, out var v))
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{
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total += ch == 'H' ? v * 3600 : ch == 'M' ? v * 60 : v;
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num = "";
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}
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}
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return total;
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}
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}
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