I need a short (20 seconds) audio fragment from the end of a long (1 hour, 40 minutes) clip, so I cropped this long clip to the desired length. Preview works, but rendering gave me an extremely low-pitched version of the audio, like rumbling. Cutting the clip in kdenlive doesn't solve the problem, editing in audacity is a workaround. Looks like a bug, https://bugs.kde.org/ seems to be out of order, will report when it is back...