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using System;
using System.Threading;
using System.Threading.Tasks;
using MediaBrowser.Common.Configuration;
using MediaBrowser.Model.Configuration;
using MediaBrowser.Model.IO;
using Microsoft.Extensions.Logging;
namespace MediaBrowser.Controller.MediaEncoding;
/// <summary>
/// Transcoding throttler.
/// </summary>
public class TranscodingThrottler : IDisposable
{
private readonly TranscodingJobDto _job;
private readonly ILogger<TranscodingThrottler> _logger;
private readonly IConfigurationManager _config;
private readonly IFileSystem _fileSystem;
private readonly IMediaEncoder _mediaEncoder;
private Timer? _timer;
private bool _isPaused;
/// <summary>
/// Initializes a new instance of the <see cref="TranscodingThrottler"/> class.
/// </summary>
/// <param name="job">Transcoding job dto.</param>
/// <param name="logger">Instance of the <see cref="ILogger{TranscodingThrottler}"/> interface.</param>
/// <param name="config">Instance of the <see cref="IConfigurationManager"/> interface.</param>
/// <param name="fileSystem">Instance of the <see cref="IFileSystem"/> interface.</param>
/// <param name="mediaEncoder">Instance of the <see cref="IMediaEncoder"/> interface.</param>
public TranscodingThrottler(TranscodingJobDto job, ILogger<TranscodingThrottler> logger, IConfigurationManager config, IFileSystem fileSystem, IMediaEncoder mediaEncoder)
{
_job = job;
_logger = logger;
_config = config;
_fileSystem = fileSystem;
_mediaEncoder = mediaEncoder;
}
/// <summary>
/// Start timer.
/// </summary>
public void Start()
{
_timer = new Timer(TimerCallback, null, 5000, 5000);
}
/// <summary>
/// Unpause transcoding.
/// </summary>
/// <returns>A <see cref="Task"/>.</returns>
public async Task UnpauseTranscoding()
{
if (_isPaused)
{
_logger.LogDebug("Sending resume command to ffmpeg");
try
{
var resumeKey = _mediaEncoder.IsPkeyPauseSupported ? "u" : Environment.NewLine;
await _job.Process!.StandardInput.WriteAsync(resumeKey).ConfigureAwait(false);
_isPaused = false;
}
catch (Exception ex)
{
_logger.LogError(ex, "Error resuming transcoding");
}
}
}
/// <summary>
/// Stop throttler.
/// </summary>
/// <returns>A <see cref="Task"/>.</returns>
public async Task Stop()
{
DisposeTimer();
await UnpauseTranscoding().ConfigureAwait(false);
}
/// <summary>
/// Dispose throttler.
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Dispose throttler.
/// </summary>
/// <param name="disposing">Disposing.</param>
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
DisposeTimer();
}
}
private EncodingOptions GetOptions()
{
return _config.GetEncodingOptions();
}
private async void TimerCallback(object? state)
{
if (_job.HasExited)
{
DisposeTimer();
return;
}
var options = GetOptions();
if (options.EnableThrottling && IsThrottleAllowed(_job, options.ThrottleDelaySeconds))
{
await PauseTranscoding().ConfigureAwait(false);
}
else
{
await UnpauseTranscoding().ConfigureAwait(false);
}
}
private async Task PauseTranscoding()
{
if (!_isPaused)
{
var pauseKey = _mediaEncoder.IsPkeyPauseSupported ? "p" : "c";
_logger.LogDebug("Sending pause command [{Key}] to ffmpeg", pauseKey);
try
{
await _job.Process!.StandardInput.WriteAsync(pauseKey).ConfigureAwait(false);
_isPaused = true;
}
catch (Exception ex)
{
_logger.LogError(ex, "Error pausing transcoding");
}
}
}
private bool IsThrottleAllowed(TranscodingJobDto job, int thresholdSeconds)
{
var bytesDownloaded = job.BytesDownloaded;
var transcodingPositionTicks = job.TranscodingPositionTicks ?? 0;
var downloadPositionTicks = job.DownloadPositionTicks ?? 0;
var path = job.Path ?? throw new ArgumentException("Path can't be null.");
var gapLengthInTicks = TimeSpan.FromSeconds(thresholdSeconds).Ticks;
if (downloadPositionTicks > 0 && transcodingPositionTicks > 0)
{
// HLS - time-based consideration
var targetGap = gapLengthInTicks;
var gap = transcodingPositionTicks - downloadPositionTicks;
if (gap < targetGap)
{
_logger.LogDebug("Not throttling transcoder gap {0} target gap {1}", gap, targetGap);
return false;
}
_logger.LogDebug("Throttling transcoder gap {0} target gap {1}", gap, targetGap);
return true;
}
if (bytesDownloaded > 0 && transcodingPositionTicks > 0)
{
// Progressive Streaming - byte-based consideration
try
{
var bytesTranscoded = job.BytesTranscoded ?? _fileSystem.GetFileInfo(path).Length;
// Estimate the bytes the transcoder should be ahead
double gapFactor = gapLengthInTicks;
gapFactor /= transcodingPositionTicks;
var targetGap = bytesTranscoded * gapFactor;
var gap = bytesTranscoded - bytesDownloaded;
if (gap < targetGap)
{
_logger.LogDebug("Not throttling transcoder gap {0} target gap {1} bytes downloaded {2}", gap, targetGap, bytesDownloaded);
return false;
}
_logger.LogDebug("Throttling transcoder gap {0} target gap {1} bytes downloaded {2}", gap, targetGap, bytesDownloaded);
return true;
}
catch (Exception ex)
{
_logger.LogError(ex, "Error getting output size");
return false;
}
}
_logger.LogDebug("No throttle data for {Path}", path);
return false;
}
private void DisposeTimer()
{
if (_timer is not null)
{
_timer.Dispose();
_timer = null;
}
}
}
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