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using MediaBrowser.Common.Configuration;
using MediaBrowser.Model.Configuration;
using System;
using MediaBrowser.Model.IO;
using MediaBrowser.Model.Threading;
using Microsoft.Extensions.Logging;
namespace MediaBrowser.Api.Playback
{
public class TranscodingThrottler : IDisposable
{
private readonly TranscodingJob _job;
private readonly ILogger _logger;
private ITimer _timer;
private bool _isPaused;
private readonly IConfigurationManager _config;
private readonly ITimerFactory _timerFactory;
private readonly IFileSystem _fileSystem;
public TranscodingThrottler(TranscodingJob job, ILogger logger, IConfigurationManager config, ITimerFactory timerFactory, IFileSystem fileSystem)
{
_job = job;
_logger = logger;
_config = config;
_timerFactory = timerFactory;
_fileSystem = fileSystem;
}
private EncodingOptions GetOptions()
{
return _config.GetConfiguration<EncodingOptions>("encoding");
}
public void Start()
{
_timer = _timerFactory.Create(TimerCallback, null, 5000, 5000);
}
private void TimerCallback(object state)
{
if (_job.HasExited)
{
DisposeTimer();
return;
}
var options = GetOptions();
if (options.EnableThrottling && IsThrottleAllowed(_job, options.ThrottleDelaySeconds))
{
PauseTranscoding();
}
else
{
UnpauseTranscoding();
}
}
private void PauseTranscoding()
{
if (!_isPaused)
{
_logger.LogDebug("Sending pause command to ffmpeg");
try
{
_job.Process.StandardInput.Write("c");
_isPaused = true;
}
catch (Exception ex)
{
_logger.LogError(ex, "Error pausing transcoding");
}
}
}
public void UnpauseTranscoding()
{
if (_isPaused)
{
_logger.LogDebug("Sending resume command to ffmpeg");
try
{
_job.Process.StandardInput.WriteLine();
_isPaused = false;
}
catch (Exception ex)
{
_logger.LogError(ex, "Error resuming transcoding");
}
}
}
private bool IsThrottleAllowed(TranscodingJob job, int thresholdSeconds)
{
var bytesDownloaded = job.BytesDownloaded ?? 0;
var transcodingPositionTicks = job.TranscodingPositionTicks ?? 0;
var downloadPositionTicks = job.DownloadPositionTicks ?? 0;
var path = job.Path;
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);
return false;
}
public void Stop()
{
DisposeTimer();
UnpauseTranscoding();
}
public void Dispose()
{
DisposeTimer();
}
private void DisposeTimer()
{
if (_timer != null)
{
_timer.Dispose();
_timer = null;
}
}
}
}
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