Audio clipping/stuttering


#1

Hi, have just tried editing a 2 minute video made up of 3 clips with video/audio fade at beginning and end of each, and there are various points throughout where the audio is clipping/stuttering, same after exporting, does anyone know why this might be?

Thanks for reading :slight_smile:


#2

@Herpaderp, Can you provide steps on how reproduce the same issue you have?
Shotcut version number? (Help/About Shotcut)
Operating system?
Computer specifications?
Video Mode?
Source file specifications? (type/resolutions/fps)
Export preset used? - Any changes after preset selected?


#3

If you are mixing audio, you are responsible for adjusting levels if needed to prevent clipping; Shotcut does not try to do that for you automatically. It simply mixes. That is not considered a bug. Of course, this assumes you are properly using the term “clipping” which is when audio levels reach their maximum.

It is hard to understand what you mean by “stuttering” but if this occurs at cut-points/edits including transition points, then it can be due to the inability to seek accurately enough on this audio codec and file format. Some people work around this with 2 frame fade out and 2 frame fade in around the cut point. Another workaround is to save the audio from the video clip as WAV and use that for your audio instead since this format seeks accurately.


#4

Hi thanks for replying, as follows:
Shotcut version - 18.11.18
OS - Windows 10 pro 64-bit
Specs - AMD 8-core 3.79 Ghz, Ram 16 GB
Video mode - Automatic
Source files specs (video) - WMV, Frame width 960, Frame height 720, Data rate 10,000 kbps, bitrate 10,128 kbps, Frame rate 29.97 fr/second, (audio) - bit rate 128kbps, stereo, audio sample rate 48,000 khz (this was a convert from windows movie maker as wanted to change from mp4 originally)
Export preset - Have tried both default (mp4) and wmv, made no changes to these presets

Any advice appreciated, thanks!


#5

Hi thanks for replying,

It both seems to clip and ‘stutter’ as if it’s something to with processing (probably less to do with mixing though can’t be sure). Side-note: When I put a gain or normalise filter on the track there seems to be a delay in this working i.e. I start the video, once fade in has completed there is a few seconds before the normalise or gain filter starts working then volume dips again…

With the stuttering, it seems to happen at random points throughout the video, sometimes at transition points and sometimes in the middle of a clip. Will try saving the audio separately as wav, sorry can you advise how to do this in shotcut?

Many thanks!


#6

Are you working with one video source file that is split into 3 clips, or just three video source files? If you are working with two other source files, are they the same specifications?


#7

Just click the WAV preset, then export file.
shotcut_2018-12-03_07-53-18


#8

Thanks, working with just one video source file split into 3 clips. Also just tried exporting audio file separately and using this alongside the video track muted and still same problem.

Could this be something to do resource allocation on the computer? i.e. antivirus etc interfering with video processing


#9

Detaching audio from one clip:

Select clip (will be outlined in red and turn a darker blue)
Right click, Detatch Audio
2018-12-06_12-11-22

Center clip audio is now detached on an Audio track (A1)
shotcut_2018-12-06_12-11-47
Playhead location 1:40 : shotcut_2018-12-06_12-12-41

Left click on V1 (track header), Right click same spot, select Remove Track.
shotcut_2018-12-06_12-13-26
shotcut_2018-12-06_12-15-23

Export, using export preset: Audio / WAV
shotcut_2018-12-06_12-14-52
CRTL + Z (Undo) – this brings back the removed video track.
Right click on any track header : Add Audio Track (A2)
shotcut_2018-12-06_12-16-31

Import WAV file from where you saved it. Drag from Source to A2.
shotcut_2018-12-06_12-17-59

The extracted audio could be modified using Audacity or whatever other software you wish to use for audio editing. The reason why I didn’t move the A1’s clip to the left, thus removing any dead space before exporting to WAV is to make it easy for re-alignment once the clip is modified. You’re able to import the audio file, and it will perfectly aligned with your video like it once was.


#10

You don’t have to extract each one separately.


A1 is left for demonstration purposes, I would have deleted A1’s contents, or at least muted it.


#11

Thanks Hudson, just tried it but still same problem :frowning:

Wondering if is a computer problem, I have a recurring problem with audio dropouts in music software and I also need to keep turning my external soundcard on/off when speakers go all crackly and fuzzy after a while (this seems to reset the problem for some reason). Any other ideas you have much appreciated though! Thanks


#12

Okay seem to have sorted the problem, I think the cause was either that I’d imported a video clip that had already been slightly edited and exported from windows movie maker, or it was to do with current problems between my computer and the external soundcard. I’ve imported the original video source file unedited and bypassed my external soundcard (headphones directly from PC) and seems to work fine now.

Thanks for all help and guidance :slight_smile: