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• avutil : add thread executor

  29 août 2023, par Nuo Mi

  avutil : add thread executor
  The executor design pattern was introduced by java
  
  <https://docs.oracle.com/en/java/javase/20/docs/api/java.base/java/util/concurrent/Executor.html> ;
  
  it also adapted by python
  
  <https://docs.python.org/3/library/concurrent.futures.html> ;
  
  Compared to handcrafted thread pool management, it greatly simplifies the thread code.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] doc/APIchanges
  • [DH] libavutil/Makefile
  • [DH] libavutil/executor.c
  • [DH] libavutil/executor.h
  • [DH] libavutil/version.h

• ffmpeg command to scale, show images at exactly 130bpm [closed]

  17 août 2023, par S. Imp

  I have a sequence of images which I would like to display to some music that plays at 130bpm. I'll also need to scale the images, which are a rather strange 2673x2151 pixels each down to something, ideally something that would fit without stretching inside a 1080p frame — e.g. 1342x1080.

  


  130BPM yields weirdness with frame rates. There are 2.16666666667 (13/6) beats per second. This being the case, I can't figure out how many frames to show each each image at the usual frame rates (24, 25, 30 fps). If I could make a movie with a frame rate of 2.16666667 frames per second, i could simply show each image for one frame. This seems like it might actually be optimal — it would probably make a a very compact video file, right ??

  


  Alternatively, if we must set the frame rate to an positive integer value, 13 frames per second works if we just display each image for six frames. 13 FPS means 780 frames per minute. 780 frames divided by 130 beats means 6 frames per beat.

  


  Finally, my images are named j1.jpg, j2.jpg, j3.jpg, etc.

  


  Can someone help me concoct an ffmpeg command to assemble these images into a video with each image lasting one beat at 130BPM ? I've been trying to massage this command, which does assemble the images into a movie, but my attempts to specify a frame rate have had weird effects. E.g., doing a -r results in strange videos that change image very erratically. I think it's because there's a setpts=N/25/TB bit in there.

  


  ffmpeg -pattern_type glob -i "j*.jpg" -filter_complex "[0]reverse[r];[0][r]concat,loop=2:250,setpts=N/25/TB,scale=1342:1080" -pix_fmt yuv420p -c:v libx264 -preset slow -b:v 3500k output_looped.mp4


  


  Also, I don't understand what the 250 means in loop=2:250. If someone could explain that to me, I'd be grateful.

  


• How to install FFMPEG on Docker Image ? [closed]

  20 avril 2023, par BS Kim

  I'm working on an m1 MacBook.

  


  I have to make it into a docker image this time, but FFMPEG keeps getting in trouble.

  


  FROM openjdk:17-oracle
ENV APP_HOME=/Users/username/Documents/coding/
WORKDIR $APP_HOME
COPY build/libs/\*.jar application.jar
RUN apk add  --no-cache ffmpeg
EXPOSE 8080

CMD ["java", "-jar", "application.jar"]



  


  I set Dockerfile as above, but both apt-get and apk have command not file errors.(Not when building docker)

  


  How can I install or use FFMPEG inside my docker imgae ?

  


  I tried

  


  RUN apk add  --no-cache ffmpeg


  


  and

  


  RUN apt-get -y update
RUN apt-get -y upgrade
RUN apt-get install -y ffmpeg


  


  but neither works.