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• High Quality Screen Capture with FFmpeg

  18 novembre 2015, par plumzl

  I’m trying to figure out a command for high quality screen capture on REHL.

  I have tried various options, but none really worked. The quality is not good enough. I’m quite new to ffmpeg and doesn’t quite understand all the different flags. So any help would be appreciated !

  The commands I have tried :

  ffmpeg -y -f x11grab -r 30 -s 1920x1080 -i :0.0+0,0 -vcodec libx264 -strict -2 -b:v 16M output.mov

  The first command I tried. The weird thing is it doesn’t seem to preserve the bitrate specified -b:v 16M. The output video’s bitrate is only 2mb/s. Is that not the correct way to specify bitrate when doing screen capture ?

  ffmpeg -f x11grab -s 1920x1080 -r 30 -i :0.0 -qscale 0 -vcodec huffyuv output.mov

  The huffyuv codec is supposed to be lossless, but the quality doesn’t seem to be any better than the libx264 output.

  ffmpeg -f x11grab -r 30 -s 1920x1080 -i :0.0+0,0 -vcodec copy -pix_fmt yuv420p -qscale 0 -an output.mkv
  
  ffmpeg -f rawvideo -pix_fmt yuv420p -s:v 1920x1080 -r 30 -i output.mkv -an -c:v libx264 -qscale 0 result.mov 

  I’m even trying to capture rawvideo and then convert it to libx264 codec viedeo. But the output is corrupted.

  I’m using the version of ffmpeg that’s built on April 23rd this year. It doesn’t have the preset like -vpre lossless_ultrafast which I see mentioned in a lot posts.

  Edit :

  After more research, this is the command I end up using. I have to use h264 codec and yuv420p as pixel_fmt since I need to be able to play the quicktimes using quicktime.

  ffmpeg -y -f x11grab -framerate 30 -video_size 1920x1080 -i :0.0+0,0 -c:v libx264 -pix_fmt yuv420p -qp 0 -preset ultrafast output.mov

  The quality doesn’t seem to be much improved even though -qp is set to 0. But it could also because of the rgb conversion to yuv color space according to this post.

  https://trac.ffmpeg.org/wiki/Encode/H.264

• fluent-ffmpeg throwing SIGSEGV in nodejs

  22 mars 2023, par C G

  I am using fluent-ffmpeg to resize a video, split into frames, etc.
Here's my code :

  


  ffmpeg("./uploads/video.mp4")
    .output("./uploads/small-video.mp4")
    .noAudio()
    .size('320x?')
    .on('end', function() {
        extractVideoFrames("./uploads/small-video.mp4")
    })
    .run()


  


  I am getting a SIGSEGV error, which I suspect might be because of some weird memory issue ?
Here's the error :

  


  Error: ffmpeg was killed with signal SIGSEGV&#xA;    at ChildProcess.<anonymous> (/home/admin/superformweb/node_modules/fluent-ffmpeg/lib/processor.js:180:22)&#xA;    at ChildProcess.emit (node:events:513:28)&#xA;    at ChildProcess._handle.onexit (node:internal/child_process:291:12)&#xA;Emitted &#x27;error&#x27; event on FfmpegCommand instance at:&#xA;    at emitEnd (/home/admin/superformweb/node_modules/fluent-ffmpeg/lib/processor.js:424:16)&#xA;    at /home/admin/superformweb/node_modules/fluent-ffmpeg/lib/processor.js:433:16&#xA;    at wrapper (/home/admin/superformweb/node_modules/async/dist/async.js:271:20)&#xA;    at next (/home/admin/superformweb/node_modules/async/dist/async.js:5795:24)&#xA;    at /home/admin/superformweb/node_modules/async/dist/async.js:327:20&#xA;    at wrapper (/home/admin/superformweb/node_modules/async/dist/async.js:271:20)&#xA;    at next (/home/admin/superformweb/node_modules/async/dist/async.js:5795:24)&#xA;    at /home/admin/superformweb/node_modules/async/dist/async.js:327:20&#xA;    at /home/admin/superformweb/node_modules/fluent-ffmpeg/lib/capabilities.js:519:16&#xA;    at handleExit (/home/admin/superformweb/node_modules/fluent-ffmpeg/lib/processor.js:170:11)&#xA;&#xA;</anonymous>

  


  I have installed ffmpeg first : sudo apt-get install ffmpeg
Then I installed node packages :

  


  npm install ffmpeg
npm install fluent-ffmpeg


  


• Concatenate Movies from Python List using MoviePy or FFmpeg

  24 septembre 2020, par Python_Learner_DK

  I have about 10,000 short videos that I am trying to make several longer videos from.

  



  I've created these videos using MoviePy, but keep getting memory errors when trying to concatenate them back together.

  



  In my code I have an outer loop going through each letter of the alphabet and getting the files that start with that letter.

  



  From the returned video clips I get the length and and strip off the last 3.5 seconds (outro_clip_duration) of the video, and then add it into a Python list clips.

  



  Where I'm stuck is I then want to take this list of trimmed videos and make one long long video from it.

  



  I have all the files, I just need to trim them, concatenate them, and then export them as one.

  



  I've tried many times with different MoviePy attempts and keep getting MemoryErrors so I gave up and took a swing at an ffmpeg solution seen here but it is not working out either.

  



  The latest version of the main part of my code is here :

  



  clips = []
outro_clip = mpy.VideoFileClip('Logo_Intro_w_Stinger_Large.mp4')
outro_clip_duration = outro_clip.duration
for def_image in vid_list_long:
    video_item = mpy.VideoFileClip('F:/sm_My_Video/sm_%s.mp4' % def_image)
    video_item_duration = video_item.duration
    clips.append(ffmpeg_extract_subclip(video_item,0,(video_item_duration - outro_clip_duration), targetname = def_image))

# #Append the outro_clip to the end 
clips.append(mpy.VideoFileClip('Logo_Intro_w_Stinger_Large.mp4',target_resolution = (h,w),audio=True))
slided_clips = [CompositeVideoClip([clip.fx( transfx.crossfadein, transition_seconds)]) for clip in clips]
#added 'method = compose' NEED TO TEST - supposedly removes the weird glitches.
c = concatenate_videoclips(slided_clips, method = 'compose')
c.write_videofile('F:/Extended_Play/%s_Extended_Play_vid.mp4' % letter,fps=23.98)


  



  My PC is Windows 10 and I have 32 GB of RAM running Anaconda and Python 3.