[LAU] kdenlive - audio time delay

[Lorenzo Sutton]

Hi Daniel,

On 01/10/19 19:46, Daniel wrote:
> Hi Friends! Thank you very much for answering!
> Unfortunately you did not quite get where the problem is: I need timeline
> markers in kdenlive timeline where i can easy snap my video cuts to. And
> these markers should be exactly on the beats od the audio, of course.
> Unfortunately i cannot bring them there, because of the delay. When i tap in
> the beats while listening all of them are a litttle late...
> It doesen't help to shift the audio track, that would have been possible,
> but the markers are linked to the audio, so they will be shifted as well, no
> help. i would have to shift all the markers to the left for the amount of
> delay, but thats not possible...
> I need to find out, why the audio, i am listening to has this little bit of
> latency, where it is coming from... to eliminated the source...
> I don't know, why this problem isn't affecting a lot of other people having
> their workflow in kdenlive, because you always want your cuts to be aligned
> to the music beats, correct?


Unfortunately I have only experience 'the other way round': I have done 
a soundtrack on Linux. But in my case I was getting video cuts and 
synchronising the music to the video, in some cases even to the frame. 
At the time I was using xjadeo and jack transport as master working 
mainly with Rosegarden and Ardour. I believe xjadeo (and equivalent 
functionality) is now integrated in Ardour.

If I understand correctly, in your case you are trying to sync the video 
to audio (i.e. you already have the audio and are cutting / editing) the 
video.

Only option I could think of is to try another video editor. For your 
use-case ShotCut comes to minde as it should support jack audio and jack 
transport. [1] I know if you are using Kdenlive probably you like to use 
that, but maybe you can bear with using something else just for the cuts :)

In any case one option would be to use the visual waveform as clue.. Not 
the best in Kdenlive honestly.

Another idea could be to generate a working copy of the video with the 
timecode 'hard coded' (graphically) in the video and then use this as 
precise reference for cuts. Although this probably means working in e.g. 
Ardour to get the right timecode for cuts and a couple of extra 
passages, it might work.

That said... do keep in mind that video frames means a 'quantiztion' of 
33 to 40 ms (e.g. with 25 fps), which in audio-land can me quite a lot. 
Still 500ms for audio seems really a lot as others pointed out.

One final thought: is the source audio some compressed format like mp3, 
ogg, but even flac? Generally decoding could add some lag, so try 
converting to wav (with same samplerate as the video project) and see if 
things improve?

My two cents.

Lorenzo.

[1] https://shotcut.org/features/