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• Is there an efficient way to use ffmpeg to perform a large quantity of cuts from a single file ?

  16 mars 2024, par Giuliano Oliveri

  I'm trying to cut video files into smaller chunks. (each one being one word said in the video, so they're not all of equal size)

  


  I've tried a lot of different approaches to try to be as efficient as possible, but I can't get the runtime to be under 2/3rd of the original video length. That's an issue because I'm trying to process 400+ hours of video.

  


  Is there a more efficient way to do this ? Or am I doomed to run this for weeks ?

  


  Here is the command for my best attempt so far

  


  ffmpeg -hwaccel cuda -hwaccel_output_format cuda -ss start_timestamp -t to_timestamp -i file_name -vf "fps=30,scale_cuda=1280:720" -c:v h264_nvenc -y output_file


  


  Note that the machine running the code has a 4090
This command is then executed via python, which gives it the right timestamps and file paths for each smaller clip in a for loop

  


  I think it's wasting a lot of time calling a new process each time, however I haven't been able to get better results with a split filter ; but here's the ffmpeg-python code for that attempt :

  


  Creation of the stream :

  


  inp = (
    ffmpeg
    .input(file_name, hwaccel="cuda", hwaccel_output_format="cuda")
    .filter("fps",fps=30)
    .filter('scale_cuda', '1280','720')
    .filter_multi_output('split')
)


  


  Which then gets called in a for loop

  


  (
    ffmpeg
    .filter(inp, 'trim', start=row[1]['start'], end=row[1]['end'])
    .filter('setpts', 'PTS-STARTPTS')
    .output(output_file,vcodec='h264_nvenc')
    .run()
)


  


• What encoders/decoders/muxers/demuxers/parsers/filters do I need to enable in FFMpeg for converting an mp4 video to a gif ?

  21 juin 2020, par kostik

  I am building FFmpeg with custom options to reduce the final size of apk file on android. I want just convert a mp4 file to a gif.
Following is my options specified

  


   --disable-everything
 --enable-decoder=mpeg4,mpegvideo,aac,gif,h264
 --enable-parser=aac,mpeg4video,mpegaudio,mpegvideo,gif,h264
 --enable-demuxer=mpegvideo,aac,mov,gif,h264
 --enable-muxer=mp4,gif,mov,h264
 --enable-protocol=file
 --enable-encoder=mpeg4,mov,gif,h264
 --enable-filter=scale,fps,copy,palettegen,vflip,paletteuse,crop


  


  What other options do i need to add to successfully run this command ?

  


  ffmpeg -y -i input.mp4 -vf "fps=15,scale=320:-1:flags=lanczos" -pix_fmt rgb24 output.gif


  


  or this command

  


  ffmpeg -y -i input.mp4 output.gif


  


  After I added module into Android Studio I run FFmpeg command.
Iam getting this error :

  


  2020-06-21 12:16:09.883 8871-9102/com.example.myapplication W/mobile-ffmpeg: [graph 0 input from stream 0:0 @ 0x7088243f40] sws_param option is deprecated and ignored
2020-06-21 12:16:09.885 8871-9102/com.example.myapplication W/mobile-ffmpeg: Incompatible pixel format 'rgb24' for codec 'gif', auto-selecting format 'rgb8'
2020-06-21 12:16:09.885 8871-9102/com.example.myapplication E/mobile-ffmpeg: Output pad "default" with type video of the filter instance "Parsed_scale_1" of scale not connected to any destination
2020-06-21 12:16:09.885 8871-9102/com.example.myapplication E/mobile-ffmpeg: Error reinitializing filters!
2020-06-21 12:16:09.885 8871-9102/com.example.myapplication E/mobile-ffmpeg: Failed to inject frame into filter network: Invalid argument
2020-06-21 12:16:09.886 8871-9102/com.example.myapplication E/mobile-ffmpeg: Error while processing the decoded data for stream #0:0


  


  I also tried to include FULL library and it that case everything worked as expected.

  


  Thanks for your help.

  


• How to concat videos that have different colour spaces ?

  17 avril 2023, par Ham789

  I writing a Python program that uses subprocess to automate ffmpeg. The program concatenates many videos together with the concat filter. The problem I have is that the colour of some of the videos is very washed out in the final output. I believe this is because the videos have different colour spaces. Some are B.709 and some are B.2020. The B.2020 videos are washed out.

  


  I have tried converting the B.2020 videos to B.709 before concatenating by using the following command on each video but the outputs are still washed out :

  


  ffmpeg -i input.mov -vf colorspace=all=bt709:iall=bt2020:fast=1 output.mov


  


  It wasn't clear to me which way round the arguments should go so I also tried switching the bt2020 and bt709 terms but they still look washed out but with more saturation.

  


  Is this the right approach ? Am I missing some other arguments in order to convert the B.2020 videos to B.709 while preserving their colour ?

  


  I have attached a side by side of the original and converted video.

  


  The metadata of the videos I am trying to concat are :

  


  Video 1

  


  

  • color_range=tv

  


  • color_space=bt709

  


  • color_transfer=bt709

  


  • color_primaries=bt709

  


  


  Video 2

  


  

  • color_range=tv

  


  • color_space=bt2020nc

  


  • color_transfer=arib-std-b67

  


  • color_primaries=bt2020