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Independent length adjustment of synched audio

User avatar sammuirhead
Registered Member
One of a series of posts dealing with issues I encountered trying to edit a long and complex documentary with Kdenlive - the problems I outline cost a lot of time, and require repetitive manual tasks where new features and shortcuts in the software could do the job better.
Other posts:
Export for Sound Mix
Fixing inaccurate camera sync

Independent length adjustment of synched audio for flexible editing.

The Problem:
The majority of the time I need my audio clips in the timeline to be longer than the video they are attached to, so that I can fade in and out and ensure that my cuts are less distracting, by not having a hard audio cut at the same time as a video cut. I end up with a mess of checkerboarded audio on multiple tracks. (Images to come, I'm rendering right now so they will have to wait)
Sometimes this is a noticeable L cut/J cut for effect, sometimes it is just a subtle crossfade you don't really notice.

Current Workaround
Yes, you can Split Audio, Ungroup Clips, extend the audio and then Group Clips again, but this means you have to go through this three-step process every single time you want to adjust the audio a little. I have found grouping clips to be unreliable and buggy - sometimes things group, and then later ungroup, sometimes they get moved out of sync when you use the spacer tool (I'll try to reproduce the problem with 15.12 and file a bug report if successful) and if you don't re-group the clips, you set yourself up for sync mayhem, as there is now no visible waveform on the video track, or linked audio to sync with.

So I add a couple of extra steps to this workflow:
1. Copy Video clip (includes audio)
2. Paste it somewhere nearby.
3. (on the pasted clip) Right Click>Split Audio
4. Right Click>Ungroup Clips
5. Delete pasted Video
6. Drag audio into line with original clip
7. Adjust audio as needed.

This is of course a dumb and insanely inefficient workaround, but it retains the audio information with the video clip. When working with giant timelines and a huge amount of material, I focus on safety and reliability, I want to be able to fix any problems that inevitably occur, so sometimes this means redundancy of clips and information.

Potential solutions: (some easier to implement than others!)
- 'Sync Lock' feature - this would be a type of 'Group' where I can always flexibly vary the lengths of my A+V clips individually (for those times when I need to extend the audio, i.e. most of the time) but they stay locked in sync with their related A or V clip.

- Single-track Crossfade directly on the timeline á la Shotcut & proprietary NLEs - this would still need to work in a similar way to the proposed 'Sync Lock' - about 0.001% of my video transitions have fades, whereas 80% of my audio transitions do - sometimes these are quick 2- or 3-second fades to glue a frankensteined sentence back together, sometimes they are longer atmo or music fades, often they are asymmetrical on either side of the edit.

- OMF/AAF/XML export - these exchange files allow for audio handles, meaning this wouldn't be a problem in the NLE as often - back in my Final Cut Pro days, I used to export an OMF with 2-second 'handles' on all the audio clips (see documentation) and then I (or an audio professional) could mix and manipulate the audiio clips in ProTools - there's enough extra information available for me to extend audio clips a few seconds and make the transitions smooth.
I know that this isn't such a good suggestion - A) these aren't real standards, and implementation is very tricky, probably not a fun coding adventure, and B) this still leaves me with choppy audio in the NLE - I won't know if my cuts work, and I won't be able to show a rough cut to a producer, until I have done an external sound mix.

Other Ideas?
Is this a problem for other people?
Does anybody have suggestions for other current workarounds?
Thoughts on how potential solutions might be able to be implemented in Kdenlive?
Other relevant or related bugs/problems?

NOTE: I have been using Kdenlive 9.10, I'll be upgrading to 15.12 next week, perhaps some problems will be fixed in the new version, let's see)
Free Culture videos made with Free/Libre/Open Source Software about Open Hardware, Open Data, Open Everything

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