public ChunkFile GetClosestChunk(ChunksCollectorModelByTime model)
{
var streamCfg =
_streamsConfigs.StreamSources
.FirstOrDefault(x => x.Name == model.Channel);
if (streamCfg == null)
{
throw new NoSuchChannelException(model.Channel);
}
model.channelRoot = Path.Combine(
_chunkerConfig.ChunkStorageDir,
streamCfg.Name);
model.streamSource = streamCfg;
var chunkTime = streamCfg.ChunkTime;
var minTime = GetMinChunkTimeSpan(model);
var minTimeS = minTime
.Add(-DateTimeOffset.Now.Offset)
.ToUnixTimeSeconds();
var testTime = TimeTools.SecsToDateWithOffset((int)minTimeS);
var files = GetFilesInsideTimeRange(
model.channelRoot,
minTime.AddSeconds(-2.2 * 1 * chunkTime),
minTime.AddSeconds(
1 * chunkTime * (model.HlsListSize + safeHlsLstDelta + 1))
);
var result = files
.Select(x => ChunkFileLoader.Load(x))
.Where(x => x.timeSeconds > minTimeS - streamCfg.ChunkTime)
.OrderBy(x => x.timeSeconds)
.FirstOrDefault();
if (result == null)
{
throw new NoAvailableFilesException();
}
return(result);
}
/// <summary>
/// Get the closest possible time to the target time, depending
/// on the number of chunks and the newest file.
/// If it's live, then the newest file - (n + 1) * chunkTime will
/// be returned. Note +1 because the newest is still being created.
///
/// Otherwise, the received time is returned.
/// </summary>
private DateTime GetMinChunkTimeSpan(ChunksCollectorModelByTime model)
{
var mostRecent =
Directory.GetFiles(
model.channelRoot,
"*.ts",
SearchOption.AllDirectories
).OrderByDescending(File.GetCreationTime).FirstOrDefault();
if (mostRecent == null)
{
throw new NoAvailableFilesException($"0/{model.HlsListSize}");
}
var targetTime =
model.RequestedTime
.AddSeconds(
-model.streamSource.ChunkTime * model.HlsListSize);
var newestChunk = ChunkFileLoader.Load(mostRecent);
var newestDateTime =
TimeTools.SecsToDateWithOffset(newestChunk.timeSeconds);
var totalRequiredSec =
(model.HlsListSize + safeHlsLstDelta + 1) *
(model.streamSource.ChunkTime);
if (targetTime.AddSeconds(totalRequiredSec) > newestDateTime)
{
var delta = newestDateTime - targetTime;
return(newestDateTime.AddSeconds(-totalRequiredSec)
.Add(-delta));
}
else
{
return(targetTime);
}
}
