private void AlignStaticStartParameters(Representation video)
{
var audioStartSegment = Segments.StartSegmentId();
if (audioStartSegment == null)
{
throw new ArgumentNullException("audio StartSegmentId is null");
}
var audioTimeRange = Segments.SegmentTimeRange(audioStartSegment);
if (audioTimeRange == null)
{
throw new ArgumentNullException("audio SegmentTimeRange is null");
}
var videoStartSegment = video.Segments.StartSegmentId();
if (videoStartSegment == null)
{
throw new ArgumentNullException("video StartSegmentId is null");
}
var videoTimeRange = video.Segments.SegmentTimeRange(videoStartSegment);
if (videoTimeRange == null)
{
throw new ArgumentNullException("vdeo SegmentTimeRange is null");
}
var trimOffset = audioTimeRange.Start < videoTimeRange.Start ? audioTimeRange.Start : videoTimeRange.Start;
//Set aligned start data
AlignedStartSegmentID = audioStartSegment;
AlignedTrimOffset = trimOffset;
video.AlignedStartSegmentID = videoStartSegment;
video.AlignedTrimOffset = trimOffset;
}
private void AlignDynamicStartParameters(Representation video)
{
var alignments = new List <AlignmentEntry>();
var videoStartSegment = video.Segments.StartSegmentId();
var videoSegmentId = video.Segments.PreviousSegmentId(videoStartSegment);
if (!videoSegmentId.HasValue)
{
videoSegmentId = videoStartSegment;
}
// Scan 3 video segments starting from videoSegmentId.
for (int s = 0; s < 3; s++)
{
var videoTimeRange = video.Segments.SegmentTimeRange(videoSegmentId);
if (videoTimeRange == null)
{
continue;
}
// Split duration into 3 elements to cover 4 time points in segment duration
// Start, Start+1/3*Duration, Start+2/3*Duration, Start+3/3*Duration
//
var tickOffset = videoTimeRange.Duration.Ticks / 3;
var tickStart = videoTimeRange.Start.Ticks;
for (int t = 0; t < 4; t++)
{
// Get audio SegmentId & Start time for a given time point
var timePoint = TimeSpan.FromTicks(tickStart + (t * tickOffset));
var audioSegmentId = Segments.SegmentId(timePoint);
var audioTimeRange = Segments.SegmentTimeRange(audioSegmentId);
if (audioTimeRange == null)
{
continue;
}
alignments.Add(new AlignmentEntry(videoSegmentId, videoTimeRange.Start, audioSegmentId, audioTimeRange.Start));
}
// Get Next video segment
videoSegmentId = video.Segments.NextSegmentId(videoSegmentId);
}
var audioStartSegment = videoStartSegment = null;
TimeSpan?trimmOffset = null;
// handle the unexpected
if (alignments.Count > 0)
{
var bestAlignment = (from AlignmentEntry in alignments
orderby AlignmentEntry.AudioVideoStartDiff
select AlignmentEntry).First();
videoStartSegment = bestAlignment.VideoSegmentID;
audioStartSegment = bestAlignment.AudioSegmentID;
var videoStart = bestAlignment.VideoSegmentStart;
var audioStart = bestAlignment.AudioSegmentStart;
trimmOffset = videoStart < audioStart ? videoStart : audioStart;
}
//Set aligned start data
AlignedStartSegmentID = audioStartSegment;
AlignedTrimOffset = trimmOffset;
video.AlignedStartSegmentID = videoStartSegment;
video.AlignedTrimOffset = trimmOffset;
}