/// <summary>
/// Shift all lines in "list to change" by "offset", create a matching, rate the matching and shift lines back.
/// </summary>
public double GetRatingOfOffset(double offset, SubtitleMatcher.SubtitleMatcherCache subtitleMatcherParams)
{
/*
* Other ideas for rating:
* bonus value for censecutive good bi-match ratings
*/
// move timings of every line
subtitleMatcherParams.ShiftTime(offset, false, true);
// match lines
var biMatchedLinesList = SubtitleMatcher.MatchSubtitles(subtitleMatcherParams);
double finalRating = 0;
foreach (var biMatchedLines in biMatchedLinesList)
{
double rating = RateBiMatchedLines(biMatchedLines);
// use rating^3 because that way small values will become smaller
finalRating += rating * rating * rating;
}
// shift timings back
subtitleMatcherParams.ShiftTime(-offset, false, true);
return(finalRating);
}
/// <summary>
/// This function test "iterations"-times different offsets and saves the best in "returnList".
/// The offsets will be around "centerOffset" and "2 * stepSize" is the in every direction.
/// The returnList will be filled until "Count==Capacity". At every time, "returnList" is sorted
/// by rating ("returnList[0]" has the best rating of all tested offsets).
/// </summary>
private void FindGoodOffsets(SubtitleMatcher.SubtitleMatcherCache subtitleMatcherParams, double centerOffset, double stepSize, int iterations, List <OffsetRatingTuple> returnList)
{
int sign = 1; // will alternate every iteration
for (int iteration = 0; iteration < iterations; iteration++)
{
double offset = sign * (stepSize * iteration) + centerOffset;
sign *= -1;
double averageRating = GetRatingOfOffset(offset, subtitleMatcherParams);
if (returnList.Count < returnList.Capacity)
{
returnList.Add(new OffsetRatingTuple(offset, averageRating));
// if all entries are filled they have to be sorted by how good they are
// (at index 0 the rating is best)
if (returnList.Count == returnList.Capacity)
{
returnList.Sort();
}
}
else
{
// is value better than worst in return list?
if (averageRating > returnList[returnList.Count - 1].rating)
{
returnList[returnList.Count - 1].offset = offset;
returnList[returnList.Count - 1].rating = averageRating;
// bubble sort in sorted list
for (int i = returnList.Count - 1; i >= 1; i--)
{
// move value up (rating at lower index is higher) or end loop?
if (returnList[i].rating < returnList[i - 1].rating)
{
break;
}
var tmp = returnList[i];
returnList[i] = returnList[i - 1];
returnList[i - 1] = tmp;
}
}
}
}
}
