/// <summary>
/// By calling this function, all references to LineInfo in "listToChange" passed in
/// constructor can be changed. Retiming includes removing/introducing commercial breaks.
///
/// By using the "noSplitting=true" option, the whole list gets shifted as one.
/// </summary>
public void Retime(bool noSplitting = false)
{
var stopwatch = new System.Diagnostics.Stopwatch();
stopwatch.Start();
var queue = new Queue <RemainingSlice>();
// initilize first slice (with all lines)
RemainingSlice fullSlice = new RemainingSlice(new List <LineInfo>(m_referenceList), new List <LineInfo>(m_listToChange));
queue.Enqueue(fullSlice);
// just find best offset
if (noSplitting)
{
double bestOffset = FindBestOffset(fullSlice);
UtilsSubtitle.ShiftByTime(m_listToChange, bestOffset);
return;
}
// Only lines that are in the same slice (list of lines on both sides) can be matched.
// When processing the slices, a consecutive row of lines is recognized as "good". Two new
// slices (one left of the right of the row) are then created.
//
// This queue will process all these slices that have some elements in them.
while (queue.Count > 0)
{
RemainingSlice slice = queue.Dequeue();
//if(slice.listToChangeLines.Count == 0 || slice.referenceListLines.Count == 0) {
// // T O D O: these shouldn't just be moved out of the way but left in another slice
// // this is more debug code than anything else
// UtilsSubtitle.ShiftByTime(slice.listToChangeLines, 10000);
// UtilsSubtitle.ShiftByTime(slice.referenceListLines, 10000);
// continue;
//}
double bestOffset = FindBestOffset(slice);
ApplyOffset(slice, bestOffset, queue);
}
Console.WriteLine(stopwatch.ElapsedMilliseconds);
}
/// <summary>
/// Find best offset for "listToChange" so it matches "referenceList". There can be
/// multiple "peaks" if one subtitle has additional breaks the other does not have.
/// Only one of them will be returned.
/// </summary>
private double FindBestOffset(RemainingSlice slice)
{
var subtitleMatcherParams = SubtitleMatcher.GetParameterCache(slice.referenceListLines, slice.listToChangeLines);
// the tuple is (offset, rating)
var firstPassList = new List <OffsetRatingTuple>(5);
FindGoodOffsets(subtitleMatcherParams, 0, 0.3, 1000, firstPassList);
// find fine grained offsets around approximated offsets
var secondPassList = new List <OffsetRatingTuple>(5);
foreach (var offsetRatingTuple in firstPassList)
{
FindGoodOffsets(subtitleMatcherParams, offsetRatingTuple.offset, 0.01, 90, secondPassList);
}
return(secondPassList[0].offset);
}
/// <summary>
/// This function will...
/// a) move all lines to change in slice by offset
/// b) match the lines in "listToChange" and "referenceList"
/// c) find a threshold value for matchings
/// d) find the longest row of consecutive matchings that are above the threshold
/// e) create slices for lines before and lines after this "good row"
/// f) reset offset of these remaining lines and put slice into queue
/// </summary>
private void ApplyOffset(RemainingSlice slice, double offset, Queue <RemainingSlice> queue)
{
UtilsSubtitle.ShiftByTime(slice.listToChangeLines, offset);
// match lines
var subtitleMatcherParameters = SubtitleMatcher.GetParameterCache(slice.referenceListLines, slice.listToChangeLines);
var biMatchedLinesLinkedList = SubtitleMatcher.MatchSubtitles(subtitleMatcherParameters);
var biMatchedLinesList = new List <SubtitleMatcher.BiMatchedLines>(biMatchedLinesLinkedList);
biMatchedLinesList.Sort(delegate(SubtitleMatcher.BiMatchedLines x, SubtitleMatcher.BiMatchedLines y) {
return(GetStartTime(x) < GetStartTime(y) ? -1 : 1);
});
// --------------------------------------------------
// find threshold rating
double averageRating = 0;
int numRatings = 0;
foreach (var biMatchedLines in biMatchedLinesList)
{
double rating = RateBiMatchedLines(biMatchedLines);
if (rating > 0.0001) // ignore "zero" ratings
{
averageRating += rating;
numRatings++;
}
}
averageRating /= numRatings;
double thresholdValue = averageRating * 0.8;
// --------------------------------------------------
// Find longest row over threshold rating.
//
// Zero ratings may be inbetween good ratings when some
// lines couldn't get matched (for example street-sign
// translations that aren't in subtitle file in native language).
// These are stepped over: There can be a limited number of zero ratings
// ratings in the row except at the beginning and the end (these will
// get matched at a different time if possible).
int numGoodMatched = 0;
int currentRowStart = 0;
int allowedZeroRatings = 0;
int maxNumGoodMatched = -1;
int bestRowStart = 0;
for (int index = 0; index < biMatchedLinesList.Count; index++)
{
var biMatchedLines = biMatchedLinesList[index];
double rating = RateBiMatchedLines(biMatchedLines);
if (rating < thresholdValue)
{
// step over zero ratings
if (rating > 0.000001 || allowedZeroRatings-- < 0)
{
numGoodMatched = 0; // not a zero rating
}
}
else
{
// update row start/end
if (numGoodMatched == 0)
{
currentRowStart = index;
}
numGoodMatched = index - currentRowStart + 1;
// save best value
if (numGoodMatched > maxNumGoodMatched)
{
maxNumGoodMatched = numGoodMatched;
bestRowStart = currentRowStart;
}
allowedZeroRatings = 4;
}
}
// could good row be found?
if (maxNumGoodMatched == -1)
{
return;
}
// create new slices left and right
RemainingSlice newSlice;
// left slice
newSlice = GetSubSlice(biMatchedLinesList, 0, bestRowStart);
//UtilsSubtitle.ShiftByTime(newSlice.listToChangeLines, -offset); // by disabling this code, remaining slices are now embedded in greater slices
queue.Enqueue(newSlice);
// right slice
newSlice = GetSubSlice(biMatchedLinesList, bestRowStart + maxNumGoodMatched + 1, biMatchedLinesList.Count);
//UtilsSubtitle.ShiftByTime(newSlice.listToChangeLines, -offset);
queue.Enqueue(newSlice);
}
