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using MediaBrowser.Model.Logging;
using System;
using System.IO;
using System.Threading;
namespace MediaBrowser.Api.Playback
{
public class TranscodingThrottler : IDisposable
{
private readonly TranscodingJob _job;
private readonly ILogger _logger;
private Timer _timer;
private bool _isPaused;
private readonly long _gapLengthInTicks = TimeSpan.FromMinutes(2).Ticks;
public TranscodingThrottler(TranscodingJob job, ILogger logger)
{
_job = job;
_logger = logger;
}
public void Start()
{
_timer = new Timer(TimerCallback, null, 5000, 5000);
}
private void TimerCallback(object state)
{
if (_job.HasExited)
{
DisposeTimer();
return;
}
if (IsThrottleAllowed(_job))
{
PauseTranscoding();
}
else
{
UnpauseTranscoding();
}
}
private void PauseTranscoding()
{
if (!_isPaused)
{
_logger.Debug("Sending pause command to ffmpeg");
try
{
_job.Process.StandardInput.Write("c");
_isPaused = true;
}
catch (Exception ex)
{
_logger.ErrorException("Error pausing transcoding", ex);
}
}
}
private void UnpauseTranscoding()
{
if (_isPaused)
{
_logger.Debug("Sending unpause command to ffmpeg");
try
{
_job.Process.StandardInput.WriteLine();
_isPaused = false;
}
catch (Exception ex)
{
_logger.ErrorException("Error unpausing transcoding", ex);
}
}
}
private bool IsThrottleAllowed(TranscodingJob job)
{
var bytesDownloaded = job.BytesDownloaded ?? 0;
var transcodingPositionTicks = job.TranscodingPositionTicks ?? 0;
var downloadPositionTicks = job.DownloadPositionTicks ?? 0;
var path = job.Path;
if (downloadPositionTicks > 0 && transcodingPositionTicks > 0)
{
// HLS - time-based consideration
var targetGap = _gapLengthInTicks;
var gap = transcodingPositionTicks - downloadPositionTicks;
if (gap < targetGap)
{
//_logger.Debug("Not throttling transcoder gap {0} target gap {1}", gap, targetGap);
return false;
}
//_logger.Debug("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 ?? new FileInfo(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.Debug("Not throttling transcoder gap {0} target gap {1} bytes downloaded {2}", gap, targetGap, bytesDownloaded);
return false;
}
//_logger.Debug("Throttling transcoder gap {0} target gap {1} bytes downloaded {2}", gap, targetGap, bytesDownloaded);
return true;
}
catch
{
//_logger.Error("Error getting output size");
return false;
}
}
//_logger.Debug("No throttle data for " + path);
return false;
}
public void Dispose()
{
DisposeTimer();
}
private void DisposeTimer()
{
if (_timer != null)
{
_timer.Dispose();
_timer = null;
}
}
}
}
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