Matching up rate_scaler audo effect with speed video effect

So I like to sometimes repeat a clip after showing it in real time but in slow motion, when I apply the speed video effect the audio is muted, removed or whatever. So I first split the audio from my clip, then I ungroup the audio and video. I then apply the speed effect to the video clip to something that looks good and then I try to apply the audio effect rate_scaler to the audio clip and it never really is perfect, in fact it's damn hard to get them close. Not to mention the audio rate_scaler is not in a percentage like the video speed effect. It start at 10 which I have no idea what that means but I am not an audio person so that doesn't say much. Can anyone suggest a better way of trying to get the audio of a video clip slowed down to match the slowed down video?


PS Loving kdenlive and all the support you guys give here on the forums. Keep up the great work!

Currently, any audio filter that messes with the temporal nature of the audio does not necessarily work well with the way MLT works. I left this audio effect in Kdenlive when I reviewed audio effects for the 0.7.8 release because it does do something interesting and potentially useful. Based on personal experience and what I have read around here, you are venturing into new territory here by trying to use alongside the video speed effect. One thing to try is to place the same clips with the same edit points on an audio track, render to an audio file, note the duration of the movie in Kdenlive, and import the audio file into an audio editor, trim out the silence, stretch it to the movie duration, export it, and place it on an audio track in Kdenlive.

ok well, not sure how scalable this solution is but this is what i did
1. import video clip into kdenlive
2. make cuts where you want the video to be slow-motion
3. split audio from that area you made cuts to
4. ungroup audio and video
5. apply speed video effect to video portion of the clip you want slow motion
6. i choose 50% but that's just me, double click on that portion and it should show you the duration of the video, note that down. so notice the video duration increased but the audio is still shorter in duration.
7. ***NOTE*** if you have other video and audio you want in the final render you'll need to ensure audio is moved further down the timeline to line back up with the video since applying the speed effect. if you noticed it made that portion of the video longer duration and since we ungrouped the audio and video, the video further in the timeline will move but the audio wont.
7. save project as foo.kdenlive
8. erase all other stuff besides the audio you want slowed down.
8. save as foo_audio.kdenlive
9. chose to render the foo_audio.kdenlive project but chose audio render only to 48000 wav file naming it foo1.wav.
10. open foo1.wav in audacity
11. apply audio effect change tempo (if you don't want pitch affected) OR change speed (but this will also change the pitch) i told it to change by -50 cause that's the percentage i changed video in kdenlive.
12. after it resamples the audio, check to see if the audio track is now the same duration as your slowed down video clip was in kdenlive.
13. if it's good, export as 48000 wav file to foo2.wav
14. go back to foo.kdenlive, erase normal audio that was below video track that you slowed down and add the foo2.wav file to the project.
15. move foo2.wav file below video portion that you added speed effect to by lining up the beginning of the foo2.wav clip to the beginning of the slowed down video clip edit point.
16. it should all line up if you check it in the project monitor.

Very painstaking to do in my opinion but if someone else sees another easier way please do inform.
ALL DONE, render to whatever you want. Hope this helps anyone else.