Weird vertical stripes

[Michael Heuberger]

Looks like a bug. Any ideas why ffmpeg encoded like this? See attached image.

Trying to generate two videos in one go (MP4 and WebM) based on image frames with this long command:

ffmpeg -f image2 -thread_queue_size 4096 -framerate 20.0 
-i ./frames/%d.webp -y -an 
-vcodec libx264 
-filter:v scale=trunc(iw/2)*2:trunc(ih/2)*2,hflip,drawtext=fontfile=./fonts/Varela-Regular.ttf:text=test-video:fontsize=14:fontcolor=0xFFFFFF@0.6:x=text_h/1.5:y=main_h-(text_h*2):shadowcolor=0x111111@0.6:shadowx=1:shadowy=1 
-crf 18 -pix_fmt yuv420p -preset medium -profile:v baseline 
-level:v 3.1 -movflags +faststart ./video_good.mp4 
-vcodec libvpx 
-filter:v scale=trunc(iw/2)*2:trunc(ih/2)*2,hflip,drawtext=fontfile=./Varela-Regular.ttf:text=test-video:fontsize=14:fontcolor=0xFFFFFF@0.6:x=text_h/1.5:y=main_h-(text_h*2):shadowcolor=0x111111@0.6:shadowx=1:shadowy=1 
-crf 4 -pix_fmt yuv420p -deadline good -cpu-used 1 
-loglevel warning ./video_good.webm

Does it look like a bug? I cannot always reproduce it and only seems to happen from some images generated from some webcam models of my visitors.

Not sure, could be something else. Thanks.

[mkver]

Does "I cannot always reproduce it" mean that it does happen sometimes and sometimes not with the same input image sequence or that it only happens with some input image sequences, but not with others? In any case, please share such an image sequence even when the problem occurs only randomly.

[Michael Heuberger]

@mkver sorry, to be precise, I don't have the images on my side. It's a web app and only happens for some users. I do not have the image frames on my side.

Maybe you have a guess what it could be or find any problems with the above command? Or it is a known bug?