Contributing to Kdenlive

Wed Aug 22 14:31:53 BST 2018

@Eugen and Jean

I have figured out what the problem was.
Eugen's suspicions regarding the frame rate being a factor, turned out to be spot on.

When I render the 60FPS project I get the audio pops, however when I switch the profile to 23.96 or 25FPS, they disappear.
Obviously the audio is otherwise unusable with multiple silent portions since I switched from a 60FPS to a 23FPS profile mid-project, which you cannot/should'nt do, but it confirms the source of the problem.

The pops do not occur right away, it's mostly fine for about 1 - 2 minutes, but after that they start popping up, so the out of synch issue Eugen talked about makes a lot of sense.

Unfortunately, I cannot simply use a 23 or 25FPS profile from now on, because I use a lot of Slide animations which I need to be rendered at 60FPS, and I don't see how else this can be achieved, other than using a 60FPS profile.

Do you guys have any idea how I can keep exporting the video at 59FPS and still solve the audio/out of synch issue Eugen spoke of?

Regards

John

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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On August 21, 2018 11:13 PM, johnar1 <johnar1 at protonmail.com> wrote:

> Hey Eugen!
>
> Thank you for your great insights.
>
> Yes, I use a 59.9FPS 1080p video profile and I am almost positive that the entire audio is 44100 Hz. So you are saying that this is a known issue under these specific conditions? (I will do my research right now, thank you!)
>
> I always try to cut audio when there is silence, to be more specific, I make MMA Youtube videos, and mostly edit interviews. I make my cuts exclusively during pauses or outro sections.
>
> But the pops also occur randomly with clips that I did not cut/edit at all or of which I positively know that they are cut correctly without any lingering sound pieces at the beginning, but you have already given a good explanation now.
>
> I will compile the latest ffmpeg, ffplay and ffprobe and report back.
> Is there anything else I should consider regarding this out of synch issue?
>
> Maybe increase the Hz of the audio that I use?
>
> Regards
>
> John
>
> Sent with [ProtonMail](https://protonmail.com) Secure Email.
>
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On August 21, 2018 8:53 PM, Eugen Mohr <eugen.mohr at gmx.net> wrote:
>
>> Hi John
>>
>> It comes 2 things to my mind:
>> -    Do you cut the audio at the zero point? In Audition (for example) is a function that you can cut only at that point (when the wave goes through zero) to avoid clicks.
>> -    When audio frequency (i.e. 44.1kHz) and video frequency (i.e. 60fps) interfere each other after a time and from there you get clicks. Video rendering is always video frequency driven. This would be a FFMPEG problem.
>>
>> Merlimau
>>
>> Am 21.08.2018 um 19:55 schrieb johnar1:
>>
>>> Hey Jean, thank you for that valuable info.
>>>
>>> I have tested the 18.08 version that you linked and unfortunately the pops at the beginning of audio clips still occur, but I have made an interesting discovery.
>>> When I render the entire project, there are three pops at the beginning of 3 clips, let's say at 01:23, 02:02 and 03:15 in the time line.
>>> These audio pops only come up in the rendered output, not during playback.
>>> When I only render a small selected zone surrounding the area where I know the pop will be, it does not occur.
>>> Only when I render the full project, they appear.
>>> I have tried this with all three known audio pops that I have spotted in the fully rendered project, and each time they disappear when I only render a selected area around them.
>>>
>>> The next thing I have noticed is that switching the playback settings betwen SDL and RTAudio  can affect this issue as well.
>>>
>>> As you know me now, I will now enter full testing mode and report back to you with a more detailed analysis.
>>> I will compile the latest melt, ffmpeg and co in order to provide a full report, but I will use the AppImage versio 18.8.0 which you have suggested.
>>>
>>> Anything else I should consider?
>>>
>>> Best regards,
>>>
>>> John
>>>
>>> Sent with [ProtonMail](https://protonmail.com) Secure Email.
>>>
>>> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>>> On August 20, 2018 10:23 AM, Jean-Baptiste Mardelle [<jb at kdenlive.org>](mailto:jb at kdenlive.org) wrote:
>>>
>>>> On 18.08.2018 14:55, johnar1 wrote:
>>>>
>>>>> Hey Jean and guys!
>>>>
>>>> Hello Johnar!
>>>>
>>>>> I have uncovered a new problem with the latest stable AppImage 18.04.1 release of kdenlive which is very troublesome.
>>>>>
>>>>> Randomly, kdenlive will cause a "click" or "pop" sound at the beginning of an audio track. I have observed that this happens the most when two audio tracks are overlapping or a cut has been made at the beginning of the a clip.
>>>>>
>>>>> I have also found that audio pops disappear in the same footage disappear when switching from SDL to RTAudio in the settings.
>>>>>
>>>>> I am using a fresh install of Kubuntu 18.04 with updates and
>>>>> Mlt and ffmpeg versions all from the Appimage, so this has to be a thing in kdenlive or maybe the latest Alsa / Pulseaudio package?
>>>>>
>>>>> I have tried some stuff suggested in forums such as exporting only the audio in wav, but without luck.
>>>>
>>>> I have just uploaded the 18.08.0 AppImage containing the latest MLT. Could you check if the problem still happens ?
>>>> It is available here:
>>>>
>>>> https://files.kde.org/kdenlive/release/kdenlive-18.08.0-x86_64.AppImage.mirrorlist
>>>>
>>>> Thanks for your feedback.
>>>>
>>>> Jean-Baptiste
>>>>
>>>>> Any ideas?
>>>>>
>>>>> Regards
>>>>>
>>>>> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>>>>> On July 26, 2018 9:20 AM, Jean-Baptiste Mardelle [<jb at kdenlive.org>](mailto:jb at kdenlive.org) wrote:
>>>>>
>>>>>> On 23.07.2018 00:21, Juku Trump wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>
>>>>>> Hello Juku!
>>>>>>
>>>>>> Thanks a lot for your contribution and sorry for my late reply. Your help is very welcome. I have now merged your contribution. Regarding the tests, they need some work and currently don't all pass and crash. We need to work on that.
>>>>>>
>>>>>> Regarding other tasks, we really need to make a list of UI improvements that could be done without too much knowledge of the whole code. I will try to spend some time on it tomorrow, help is welcome. But basically, if there is any UI related thing that you want to improve, feel free to ask and we can guide you if needed.
>>>>>>
>>>>>> Best regards,
>>>>>>
>>>>>> Jean-Baptiste
>>>>>>
>>>>>>> My name is Juku. I am a film hobbyist and I have been using Kdenlive for about 8 years. As I'm also a developer, I thought I would try my hand on contributing to Kdenlive.
>>>>>>>
>>>>>>> I have mostly been a web developer so far, so I do not have much experience with C++ (except for some tutorials) and I have never done any Qt development.
>>>>>>>
>>>>>>> I viewed the "Junior Jobs" section in Kdenlive Development Information page and tried to fix #384511 for start ("New project window does not fit to laptop screen (1366x768)"). Thanks to a hint by Christoph Feck in the comments below that bug, I got it fixed and submitted the patch ([D14281](https://phabricator.kde.org/D14281)) for review.
>>>>>>>
>>>>>>> Currently I'm having some trouble with the automated tests. Should they succeed in their current state or are there some known problems with them?
>>>>>>>
>>>>>>> It would be helpful if someone would suggest some other tasks which I could start with.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Juku
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