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• Trouble concatenating with ffmpeg (threads)

  4 janvier 2014, par mistypants

  I'm writing a batch script to automate one of my video editing processes. I've gotten everything done up to the final step, when I concatenate the video intro (1080.avi) with the video itself, then output. Here's the concatenate part of the script :

  ffmpeg -i 1080.avi -i %input%-lossless.avi ^
  
  -filter_complex "[0:0] [0:1] [1:0] [1:1] concat=n=2:v=1:a=1 [v] [a]" ^
  
  -map "[v]" -map "[a]" ^
  
  -c:v libx264 -preset veryslow -pix_fmt yuv420p ^
  
  -b:a 160k ^
  
  -threads 2 %input%-final.mp4

  It seems to work fine, but my computer overheats (it's a laptop) while it runs. I had this problem with just simple conversions and ffmpeg, so I added the -threads 2 part which eliminated the problem. It's back now.

  Did I mess up something in the script, or does concatenating just use more of the CPU ? If the latter, could I just decrease it to 1 thread ?

• Why does ffmpeg error on the last image in this avi -> jpg conversion ?

  13 avril 2018, par purple_arrows

  I want to make jpeg snapshots of every tenth frame of some avi files. I also want to skip some boring initial content that’s always the same in every avi.

  I’m using the following command :

  ffmpeg -ss SECONDS-TO-SKIP -i video.avi -vf framestep=step=10 images-%03.jpg

  For some files this works fine, but for others I get the following error (where THE-FINAL-NUMBER means I only get this error on what should be the last output image) :

  [image2 @ 0x16fa6c0] Could not open file : images-THE-FINAL-NUMBER.jpg
  
  av_interleaved_write_frame(): Input/output error

  What’s up ? Am I missing some important command line flag ? And how do I fix this ?

  ffmpeg version 2.8.14-0ubuntu0.16.04.1 built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.9) 20160609

• Extremely slow rendering time using Moviepy

  15 janvier 2024, par pacorisas

  I'm trying to create the following : two stacked videos (one on top of each other) with subtitles (like those videos you see in tiktok) from an srt file. For this, I'm first taking the top and bottom video and creating a CompositeVideoClip :

  


  clips_array([[video_clip], [random_bottom_clip]])


  


  Then, I'm taking this CompositeVideoClip and using a generator, creating the SubtitlesClip which then I will add to another CompositeVideoClip :

  


  sub = SubtitlesClip(os.path.join(temp_directory, f"subtitles.srt"), generator)
final = CompositeVideoClip([myvideo, sub.set_position(('center', 'center'))]).set_duration("00:02:40")


  


  Lastly, I'm adding some more text-clips (just an small title for the video) and rendering :

  


  video_with_text = CompositeVideoClip([final] + text_clips)
video_with_text.write_videofile(part_path, fps=30,threads=12,codec="h264_nvenc")


  


  Here is the problem. I tried to render a video of 180 seconds (3 minutes) and the video takes up to hour and a half (80 minutes) which is wild. I tried some render settings as you can see like changing 'codec' and using all the 'threads' of my CPU.
I tried to not use so many CompositeVideoClips, I read that when you concatenate those the final render will suffer a lot, but I didn't manage to find a way "not to use" that many CompositeVideoClips, any idea ?

  


  My PC is not that bad. 16GB, AMD Ryzen 5 5600 6-Core , NVIDIA 1650 SUPER.

  


  My goal is to at least bring the render to less than an hour. Right now is like 1.23s/it