Moviepy: Huge quality drop on first/last seconds from single clips when concatenating

[CayoM]

Hello,

when I'm concatenating lets say 15-20 clips together, i noticed that on each clip, there is a really low quality at the start (first 1-2 seconds) and end (last 1 second) of the clips.

the only arguments im using on write_videofile are:

codec='mpeg4', 
bitrate="5000k", 
threads=8, 
temp_audiofile=final_video_file_name.replace("mp4", "mp3")

is this an known thing? I would love to know what i have to do in order to keep the quality always similar.

Many thanks

[tburrows13]

Sorry, I've never seen that problem before. Would it be possible to post the code, and the input and output media files?

[CayoM]

here is an example https://www.youtube.com/watch?v=m63_8e2Cgfc
as you can see, every time the transition video at the end gets blurry and the new clip needs 1-2 seconds untill its really sharp. Im using the settings above for each clip.

[tburrows13]

I see what you mean. I imagine that the problem is to do with the compression used by FFmpeg. Perhaps try experimenting with a different codecs and file extensions. There's a few examples here: https://github.com/Zulko/moviepy/blob/a1df46d96b34bbdd7869854705ee9c18788c2838/moviepy/video/VideoClip.py#L186.

Other than that, I'm not really sure what to suggest...

[CayoM]

yeah, you were right again and tbh i remember now having better quality before i started using mpeg4 codec. I just switched back to xlib264 (default) and the quality is much higher. Pretty strange since the documentation explicitly says mpeg4 has produces better quality for mp4.

[tburrows13]

Yeah, it is strange that the documentation says that.