Unosquare.FFmpegMediaElement.FFmpegMediaFrameCache.SearchFrame C# (CSharp) Method

        private FFmpegMediaFrame SearchFrame(decimal renderTime)
        {
            lock (SyncLock)
            {
                var frameCount = Frames.Count;

                // fast condition checking
                if (frameCount <= 0) return null;
                if (frameCount == 1) return Frames[0];

                // variable setup
                var lowIndex = 0;
                var highIndex = frameCount - 1;
                var midIndex = 1 + lowIndex + (highIndex - lowIndex) / 2;

                // edge condition cheching
                if (Frames[lowIndex].StartTime >= renderTime) return Frames[lowIndex];
                if (Frames[highIndex].StartTime <= renderTime) return Frames[highIndex];

                // First guess, very low cost, very fast
                if (midIndex < highIndex && renderTime >= Frames[midIndex].StartTime && renderTime < Frames[midIndex + 1].StartTime)
                    return Frames[midIndex];

                // binary search
                while (highIndex - lowIndex > 1)
                {
                    midIndex = lowIndex + (highIndex - lowIndex) / 2;
                    if (renderTime < Frames[midIndex].StartTime)
                        highIndex = midIndex;
                    else
                        lowIndex = midIndex;
                }

                // linear search
                for (var i = highIndex; i >= lowIndex; i--)
                {
                    if (Frames[i].StartTime <= renderTime)
                        return Frames[i];
                }

                return null;
            }

        }