Contributing to Kdenlive

Eugen Mohr eugen.mohr at gmx.net
Tue Aug 28 18:06:29 BST 2018 

Hi John

As I don’t see your timeline my guess is that this pops/clicks coming 
from audio clipping. Meaning you reach 0dB or higher because you add one 
audio on each other.

To avoid this make an audio crossfade. On 1 audio track a fade out and 
on the other a fade in.

Audio crossfade seems still on the wish list. 
https://forum.kde.org/viewtopic.php?f=270&t=127698#p340370

Eugen


Am 28.08.2018 um 16:54 schrieb Steve Brodie:
> Hi John,
>
> If it is only happening on transitions etc. could you do an export of 
> your audio only at 25fps, bring it back into Kdenlive as one 
> continuous WAV file and mute all the edited audio tracks and export 
> again at 60fps? Or does that introduce sync issues?
>
> Steve
>
>
> On 28 Aug 2018, 13:00 +0100, johnar1 <johnar1 at protonmail.com>, wrote:
>> Hi, Eugen!
>>
>> Yes, during problem there are no pops. They only appear in the 
>> rendered output file. Another thing I have noticed is, that they only 
>> happen at the beginning or end of overlapping clips when there is a 
>> transition (Slide) or Volume Keyframable Effect involved.
>>
>> Yes sir, I use Lubuntu 18.04 and Kubuntu 18.04.
>> I just checked and the clips are ususally 44.1khz 16bit.
>>
>> The only way I can get rid of all pops is if I render with a 25FPS 
>> profile.
>> 50FPS, 59.9 and 60FPS all produce the same pops.
>>
>> It's driving me so insane omg, I can't sleep anymore.
>>
>>
>> Sent with ProtonMail <https://protonmail.com> Secure Email.
>>
>> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>> On August 27, 2018 8:58 PM, Eugen Mohr <eugen.mohr at gmx.net> wrote:
>>
>>>
>>>
>>>
>>> Hi John
>>>
>>>
>>>
>>> I assume your audio file is not proper because FFMPEG can handle 
>>> 44.1kHz. As Vincent Pinon mentioned: check if the audio is: 44.1kHz, 
>>> 16 bit, WAV pcm (i.e. with the program MediaInfo). This is CD 
>>> standard. Maybe 24bits work as well.
>>>
>>> Do you have this problem at playback or after you have rendered the 
>>> video out?
>>>
>>> BTW: you are on Linux?
>>>
>>> Eugen
>>>
>>>
>>>
>>> Am 26.08.2018 um 22:28 schrieb johnar1:
>>>> Eugen, would you mind being a little more specific on what you 
>>>> meant by 44.1khz audio and 60FPS video interfering with each other 
>>>> over time, which causes clicks? I have searched everywhere on 
>>>> google but could not find anything.
>>>>
>>>> Is there a solution for this problem apart from converting every 
>>>> audio track to 48khz?
>>>> Switching the 60FPS profile to 25FPS and rendering the audio 
>>>> produces no clicks, but the audio has multiple blank parts and is 
>>>> unusable.
>>>>
>>>> Hope you can give a little more insight in this matter.
>>>>
>>>> Thanks a bunch!
>>>>
>>>>
>>>> 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> 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> 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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