Recherche avancée

Sur d’autres sites (9268)

• Correcting the variable name in an ffmpeg subtitle script

  21 juin 2017, par Steven Foong

  I have 175 mp4 video files and subtitle files with the extension .ass. Unfortunately, my smart TV is not able to read those subtitles. I plan to burn (hardcode) the subtitles into the video.

  I use this command :

  ffmpeg -i orgvideo.mp4 -vf subtitles="subtitle.ass" newvideo.mp4     <br />

  It works. So I plan to use a bash script to automate the process.

  Everything in the script is working but the ffmpeg command line isn’t able to retrieve the subtitle variable.

  After googling around, I found that my file name has special character and space, that causes my script to fail. If the video file name and the subtitle file is simple, then the script should be no problem.

  This is my script :

  for f in *.mp4
  
  do
  
      new="${f%%.mp4} (CHT).mp4"
  
      subtitle="${f%%.mp4}.chi.ass"
  
      < /dev/null ffmpeg -i "$f" -vf subtitles="$subtitle" "$new"
  
  done

  The ffmpeg line is having problems reading the subtitle file variable. Can anyone help ?

• make webbased ffmpeg-live transcoder on linux for multiple streams

  11 juillet 2017, par Dlniya Dlzar

  Hi I am planning to make webbased ffmpeg-live transcoder on linux for multiple streams .
  Using ffmpeg and ngnix-rtmp is the basic that i found and planning to do it
  my plan is (Web interface for adding and modifying streams (name ,input,output..)
  in database , database i mean (json file). and execute ffmpeg command depend on the JSON file (now one more thing i want to do , is to monitor streams based on
  nginx-rtmp-module/stat.xsl
  git https://github.com/arut/nginx-rtmp-module/blob/master/stat.xsl
  and restart streams if there is problem , like no audio or picture
  whats is best structure to do it ?? which language is good to do the proccess
  is there any missing knowledges ?? is there any other better way in your mind ??

• checkasm : use perf API on Linux ARM*

  1er septembre 2017, par Clément Bœsch

  checkasm : use perf API on Linux ARM*
  On ARM platforms, accessing the PMU registers requires special user
  
  access permissions. Since there is no other way to get accurate timers,
  
  the current implementation of timers in FFmpeg rely on these registers.
  
  Unfortunately, enabling user access to these registers on Linux is not
  
  trivial, and generally involve compiling a random and unreliable github
  
  kernel module, or patching somehow your kernel.
  Such module is very unlikely to reach the upstream anytime soon. Quoting
  
  Robin Murphin from ARM :
  > Say you do give userspace direct access to the PMU ; now run two or more
  
  > programs at once that believe they can use the counters for their own
  
  > "minimal-overhead" profiling. Have fun interpreting those results...
  
  >
  
  > And that's not even getting into the implications of scheduling across
  
  > different CPUs, CPUidle, etc. where the PMU state is completely beyond
  
  > userspace's control. In general, the plan to provide userspace with
  
  > something which might happen to just about work in a few corner cases,
  
  > but is meaningless, misleading or downright broken in all others, is to
  
  > never do so.
  As a result, the alternative is to use the Performance Monitoring Linux
  
  API which makes use of these registers internally (assuming the PMU of
  
  your ARM board is supported in the kernel, which is definitely not a
  
  given...).
  While the Linux API is obviously cross platform, it does have a
  
  significant overhead which needs to be taken into account. As a result,
  
  that mode is only weakly enabled on ARM platforms exclusively.
  Note on the non flexibility of the implementation : the timers (native
  
  FFmpeg vs Linux API) are selected at compilation time to prevent the
  
  need of function calls, which would result in a negative impact on the
  
  cycle counters.
  

  • [DH] configure
  • [DH] tests/checkasm/checkasm.c
  • [DH] tests/checkasm/checkasm.h