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• How can I tell subprocess to answer "y" to a commandline question ?

  13 mai 2022, par Faindirnomainzein

  I'm automating an ffmpeg command but when the file exists already, it asks me if I have to "Overwrite [y/N]" and it stalls the entire script until I have to enter "y" myself in the console. How can I automate that ?

  


  for file in all_files_in_dir:
    output = file.split('.')[0]
    subprocess.call(f'ffmpeg -hide_banner -i {file} -map 0:s:1 {output}.srt')


  


  I have to enter "y" myself (as seen in green), then press enter everytime a file is already found. The answer will be "y", so I can hardcode the answer "y" if need be.

  


  

  


• C program cannot find function which included in header file

  17 juin 2013, par Juneyoung Oh

  I made program like this.

    1 #include 
  
    2 #include 
  
    3 #include 
  
    4 #include "libavformat/avformat.h"
  
    5 
  
    6 int main (int argc, char* argv[]){
  
    7         av_register_all();
  
    8         return 0;
  
    9 }

  My header file located in

  root@ubuntu:/home/juneyoungoh/getDuration# find / -name "avformat.h"
  
  /root/ffmpeg/libavformat/avformat.h
  
  /usr/local/include/libavformat/avformat.h

  then I run with gcc getDuration.c , but I show message like below.

  root@ubuntu:/home/juneyoungoh/getDuration# gcc getDuration.c 
  
  /tmp/ccwjonqH.o: In function `main':
  
  getDuration.c:(.text+0x10): undefined reference to `av_register_all'
  
  collect2: ld returned 1 exit status

  Frankly, I do not have any idea what makes this.

  Thanks for your answers.

  ========================== edited #1 ===========================

  when I "ls /usr/local/lib", I get this.

  root@ubuntu:/home/juneyoungoh/getDuration# ls /usr/local/lib/
  
  libavcodec.a   libavutil.a    libopus.la       libvpx.a   python2.7
  
  libavdevice.a  libfdk-aac.a   libpostproc.a    libx264.a
  
  libavfilter.a  libfdk-aac.la  libswresample.a  libyasm.a
  
  libavformat.a  libopus.a      libswscale.a     pkgconfig

  you can see libavformat.a in the very first of the last line.

  so if I command like what you suggest, I get below.

  /root/ffmpeg/libavformat/vqf.c:244: undefined reference to `av_free_packet'
  
  /usr/local/lib//libavformat.a(vqf.o): In function `add_metadata':
  
  /root/ffmpeg/libavformat/vqf.c:58: undefined reference to `av_malloc'
  
  /root/ffmpeg/libavformat/vqf.c:64: undefined reference to `av_dict_set'
  
  /usr/local/lib//libavformat.a(vqf.o): In function `vqf_read_header':
  
  /root/ffmpeg/libavformat/vqf.c:148: undefined reference to `av_dict_set'
  
  /root/ffmpeg/libavformat/vqf.c:208: undefined reference to `av_log'
  
  /root/ffmpeg/libavformat/vqf.c:216: undefined reference to `av_malloc'
  
  /root/ffmpeg/libavformat/vqf.c:170: undefined reference to `av_log'
  
  /root/ffmpeg/libavformat/vqf.c:121: undefined reference to `av_log'
  
  /root/ffmpeg/libavformat/vqf.c:184: undefined reference to `av_log'
  
  /root/ffmpeg/libavformat/vqf.c:136: undefined reference to `av_log'
  
  /usr/local/lib//libavformat.a(wavenc.o): In function `wav_write_trailer':
  
  /root/ffmpeg/libavformat/wavenc.c:210: undefined reference to `av_rescale'
  
  /usr/local/lib//libavformat.a(wavenc.o): In function `wav_write_packet':
  
  /root/ffmpeg/libavformat/wavenc.c:181: undefined reference to `av_log'

  It is too long, so I just post little part of that.

  I think all link of libavformat has been broken, But I do not know

  what can I do to fix that link.

  I have installed that their official link said.

  https://ffmpeg.org/trac/ffmpeg/wiki/UbuntuCompilationGuideQuantal

• How to specify a non default type when calling a FFmpeg library using ctypes

  1er août 2013, par Jim Ramberg

  I am calling an FFMPEG library called avformat_alloc_context() that returns a pointer to type AVFormatContext. The structure AVFormatContext is defined in the avformat library.

  Obviously ; this is not one ctypes default types and results in an error when I try to pass a reference to it to another ffmpeg library further down in my code.

  Is there a way to add in the the classes defined inside of the library ? I read through what documentation I could find online and was not able to find a good answer to this question.