Newest 'ffmpeg' Questions - Stack Overflow

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• Saving matplotlib.animation outputs a 0 second video

  15 février 2017, par Andy Baldacchino

  I am fairly new to matplotlib and animations, the animation I have works when using pyplot.show but when attempting to use the animation.save function, the only thing outputted is a 0 second video with the initial frame of the animation.

  This is my code:

  plt.rcParams['animation.ffmpeg_path'] = r'C:\FFMPEG\bin\ffmpeg.exe'
  FFwriter = animation.FFMpegWriter()     
  video_ani.save('basic_animation1.mp4', writer = FFwriter, fps=30, extra_args=['-vcodec', 'libx264'])
  

  Any help would be appreciated, thanks

• How to choose between openH264 and x264 decoder

  15 février 2017, par Darko

  I'm using the dev build from zeranoe.com which has OpenH264 and libx264 in it. How can i choose between these two Decoders to compare the decoding speed ?

  avcodec_find_decoder(AVCodecID.AV_CODEC_ID_H264); 
  

  only gives me the name "h264" but which decoder is it ?

  And tries to force a specific decoder failed, like:

  codec = avcodec_find_decoder _by_name("x264");
  codec = avcodec_find_decoder _by_name("libx264");
  

  Which other options i have to improve the decoding speed of avcodec_decode_video2 for highres (4k and higher) RTSP video streams ?

• Concat a video with itself, but in reverse, using ffmpeg

  15 février 2017, par Vitam

  I was able to reverse with:

  ffmpeg -i input.mp4 -vf reverse output_reversed.mp4
  

  And I can concat with:

  ffmpeg -i input.mp4 -i input.mp4 -filter_complex "[0:0] [0:1] [1:0] [1:1] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" output.mp4
  

  But can I concat with a reverse version of the video, with a single command?

  What I am trying to achieve is a ping pong effect, where the video plays once, then plays backwards right after.

  Thanks!

• ffmpeg cut and concat single command line

  15 février 2017, par Gianluca Calabria

  I have two flac audio files, I need to cut them with different timecodes and then concatenated them using one single command line with ffmpeg. Is there a way to do it? I did something like that but it's not working very well, the timestamps of the outputs file are all messed up (instead of having an output flac beginning from 00:00 I have a file beginning from 59:90!!) Also this command line is insanely slow and it works only on unix system...hope someone could help me

  mkfifo temp1 temp2 
  ffmpeg -y -i PMM_20170116-1100_1.flac -ss 3590 -t 10 -c copy -acodec copy -f flac temp1 2> /dev/null  & ffmpeg -y -i PMM_20170116-1200_1.flac -ss 0 -t   3590 -c copy -acodec copy -f flac temp2 2> /dev/null & ffmpeg -f flac -i "concat:temp1|temp2" -ac 2 -ar 48000 cutmergetest.flac
  

• FFMPEG Merge two videos into one with side-by-side same quality output

  15 février 2017, par Filip Kafo Kaučiarik

  I´m already working on project with 3d video an i have problem,i got left and right channel of video a a ineed to merge it into side by side.I already read some blogs about this problem and i got this code:

  ffmpeg -i avatar35l.avi -vf "movie=avatar35r.avi [in1]; [in]pad=1920*2:1080[in0]; [in0][in1] overlay=1920:0 [out]" avatar35sbs.avi
  

  it works,but i got significant quality loss and i need a quality of output video same as input video,30fps,1080p,same lenght,i´m a new one to ffmpeg and i need a concrete example of that

  Can anybody help me?