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using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using Jellyfin.MediaEncoding.Hls.Extractors;
using Jellyfin.MediaEncoding.Keyframes;
using MediaBrowser.Common.Configuration;
using MediaBrowser.Controller.Configuration;
using MediaBrowser.Controller.MediaEncoding;
namespace Jellyfin.MediaEncoding.Hls.Playlist;
/// <inheritdoc />
public class DynamicHlsPlaylistGenerator : IDynamicHlsPlaylistGenerator
{
private readonly IServerConfigurationManager _serverConfigurationManager;
private readonly IKeyframeExtractor[] _extractors;
/// <summary>
/// Initializes a new instance of the <see cref="DynamicHlsPlaylistGenerator"/> class.
/// </summary>
/// <param name="serverConfigurationManager">An instance of the see <see cref="IServerConfigurationManager"/> interface.</param>
/// <param name="extractors">An instance of <see cref="IEnumerable{IKeyframeExtractor}"/>.</param>
public DynamicHlsPlaylistGenerator(IServerConfigurationManager serverConfigurationManager, IEnumerable<IKeyframeExtractor> extractors)
{
_serverConfigurationManager = serverConfigurationManager;
_extractors = extractors.Where(e => e.IsMetadataBased).ToArray();
}
/// <inheritdoc />
public string CreateMainPlaylist(CreateMainPlaylistRequest request)
{
IReadOnlyList<double> segments;
// For video transcodes it is sufficient with equal length segments as ffmpeg will create new keyframes
if (request.IsRemuxingVideo && TryExtractKeyframes(request.FilePath, out var keyframeData))
{
segments = ComputeSegments(keyframeData, request.DesiredSegmentLengthMs);
}
else
{
segments = ComputeEqualLengthSegments(request.DesiredSegmentLengthMs, request.TotalRuntimeTicks);
}
var segmentExtension = EncodingHelper.GetSegmentFileExtension(request.SegmentContainer);
// http://ffmpeg.org/ffmpeg-all.html#toc-hls-2
var isHlsInFmp4 = string.Equals(segmentExtension, ".mp4", StringComparison.OrdinalIgnoreCase);
var hlsVersion = isHlsInFmp4 ? "7" : "3";
var builder = new StringBuilder(128);
builder.AppendLine("#EXTM3U")
.AppendLine("#EXT-X-PLAYLIST-TYPE:VOD")
.Append("#EXT-X-VERSION:")
.Append(hlsVersion)
.AppendLine()
.Append("#EXT-X-TARGETDURATION:")
.Append(Math.Ceiling(segments.Count > 0 ? segments.Max() : request.DesiredSegmentLengthMs))
.AppendLine()
.AppendLine("#EXT-X-MEDIA-SEQUENCE:0");
var index = 0;
if (isHlsInFmp4)
{
// Init file that only includes fMP4 headers
builder.Append("#EXT-X-MAP:URI=\"")
.Append(request.EndpointPrefix)
.Append("-1")
.Append(segmentExtension)
.Append(request.QueryString)
.Append("&runtimeTicks=0")
.Append("&actualSegmentLengthTicks=0")
.Append('"')
.AppendLine();
}
long currentRuntimeInSeconds = 0;
foreach (var length in segments)
{
// Manually convert to ticks to avoid precision loss when converting double
var lengthTicks = Convert.ToInt64(length * TimeSpan.TicksPerSecond);
builder.Append("#EXTINF:")
.Append(length.ToString("0.000000", CultureInfo.InvariantCulture))
.AppendLine(", nodesc")
.Append(request.EndpointPrefix)
.Append(index++)
.Append(segmentExtension)
.Append(request.QueryString)
.Append("&runtimeTicks=")
.Append(currentRuntimeInSeconds)
.Append("&actualSegmentLengthTicks=")
.Append(lengthTicks)
.AppendLine();
currentRuntimeInSeconds += lengthTicks;
}
builder.AppendLine("#EXT-X-ENDLIST");
return builder.ToString();
}
private bool TryExtractKeyframes(string filePath, [NotNullWhen(true)] out KeyframeData? keyframeData)
{
keyframeData = null;
if (!IsExtractionAllowedForFile(filePath, _serverConfigurationManager.GetEncodingOptions().AllowOnDemandMetadataBasedKeyframeExtractionForExtensions))
{
return false;
}
var len = _extractors.Length;
for (var i = 0; i < len; i++)
{
var extractor = _extractors[i];
if (!extractor.TryExtractKeyframes(filePath, out var result))
{
continue;
}
keyframeData = result;
return true;
}
return false;
}
internal static bool IsExtractionAllowedForFile(ReadOnlySpan<char> filePath, IReadOnlyList<string> allowedExtensions)
{
var extension = Path.GetExtension(filePath);
if (extension.IsEmpty)
{
return false;
}
// Remove the leading dot
var extensionWithoutDot = extension[1..];
for (var i = 0; i < allowedExtensions.Count; i++)
{
var allowedExtension = allowedExtensions[i].AsSpan().TrimStart('.');
if (extensionWithoutDot.Equals(allowedExtension, StringComparison.OrdinalIgnoreCase))
{
return true;
}
}
return false;
}
internal static IReadOnlyList<double> ComputeSegments(KeyframeData keyframeData, int desiredSegmentLengthMs)
{
if (keyframeData.KeyframeTicks.Count > 0 && keyframeData.TotalDuration < keyframeData.KeyframeTicks[^1])
{
throw new ArgumentException("Invalid duration in keyframe data", nameof(keyframeData));
}
long lastKeyframe = 0;
var result = new List<double>();
// Scale the segment length to ticks to match the keyframes
var desiredSegmentLengthTicks = TimeSpan.FromMilliseconds(desiredSegmentLengthMs).Ticks;
var desiredCutTime = desiredSegmentLengthTicks;
for (var j = 0; j < keyframeData.KeyframeTicks.Count; j++)
{
var keyframe = keyframeData.KeyframeTicks[j];
if (keyframe >= desiredCutTime)
{
var currentSegmentLength = keyframe - lastKeyframe;
result.Add(TimeSpan.FromTicks(currentSegmentLength).TotalSeconds);
lastKeyframe = keyframe;
desiredCutTime += desiredSegmentLengthTicks;
}
}
result.Add(TimeSpan.FromTicks(keyframeData.TotalDuration - lastKeyframe).TotalSeconds);
return result;
}
internal static double[] ComputeEqualLengthSegments(int desiredSegmentLengthMs, long totalRuntimeTicks)
{
if (desiredSegmentLengthMs == 0 || totalRuntimeTicks == 0)
{
throw new InvalidOperationException($"Invalid segment length ({desiredSegmentLengthMs}) or runtime ticks ({totalRuntimeTicks})");
}
var desiredSegmentLength = TimeSpan.FromMilliseconds(desiredSegmentLengthMs);
var segmentLengthTicks = desiredSegmentLength.Ticks;
var wholeSegments = totalRuntimeTicks / segmentLengthTicks;
var remainingTicks = totalRuntimeTicks % segmentLengthTicks;
var segmentsLen = wholeSegments + (remainingTicks == 0 ? 0 : 1);
var segments = new double[segmentsLen];
for (int i = 0; i < wholeSegments; i++)
{
segments[i] = desiredSegmentLength.TotalSeconds;
}
if (remainingTicks != 0)
{
segments[^1] = TimeSpan.FromTicks(remainingTicks).TotalSeconds;
}
return segments;
}
}
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