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• libavutil : Use an intermediate variable in AV_COPY*U

  28 juillet 2016, par Martin Storsjö

  libavutil : Use an intermediate variable in AV_COPY*U
  If AV_RN and AV_WN are macros with multiple individual reads and
  
  writes, the previous version of the AV_COPYU macro would fail if
  
  the reads and writes overlap.
  This should not be any less efficient in any case, given a
  
  sensibly optimizing compiler.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavutil/intreadwrite.h

• FFMPEG : How to extract a PNG sequence from a video, remove duplicate frames in the process and keep the original frame number ?

  16 mai 2020, par Simon

  I have a recording of an old game which has variable framerate. Since I want to process individual frames to upscale and modernize the footage I would like to avoid any duplicate frames. I know that I can use this function to extract all frames from a video :

  



  ffmpeg -i input.mov -r 60/1 out%04d.png


  



  And I know that I can remove duplicate frames using this function :

  



  ffmpeg -i input.mov -vf mpdecimate,setpts=N/FRAME_RATE/TB output.mov


  



  However, the above command removes duplicate frames and puts frames next to each other whereas in order to keep a timecode of sorts it would be a lot more useful to be able to extract PNGs with frame number (video is progressive 60fps) but without all of the duplicates.

  



  So, the question is : what if I want to extract PNG files BUT maintain the original corresponding framenumber within the sequence ? So, if we have a video with 10 frames and frames 2-8 are duplicates it spits out 1.png 2.png 9.png and 10.png ? How do I combine both bits of code listed above ?

  


• Streaming MJPEG video over RTSP without re-encoding using ffmpeg in Ubuntu

  5 août 2023, par user8109

  I have a video file encoded in MJPEG format stored as .avi file. I want to stream this video without re-encoding using ffmpeg tool from an Ubuntu machine to a remote server over RTSP protocol. I could achieve this for videos encoded in H.264 format and H.265 format using the below command.

  


  ffmpeg -re -i "$input_file" -c copy -f rtsp "$output_url"


  


  But, I am getting errors when I am streaming MJPEG video. One alternative approach could be to extract individual JPEG frames and stream that over the network using the following command.

  


  ffmpeg -re -i "$input_file" -f image2pipe -vcodec mjpeg -pix_fmt yuvj420p - | ffmpeg -i - -c:v copy -an -f rtsp "$output_url"


  


  But I am getting errors here also. Any solution is fine for me.