Newest 'ffmpeg' Questions - Stack Overflow

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• How can I check compression type(lossless or lossy) for .wav, .flac and .m4a in python ?

  20 juin 2017, par Michael

  How can I check compression type (lossless or lossy) for .wav, .flac and .m4a in python?

• How to force libav to update duration for a growing file ?

  20 juin 2017, par skrew

  I have a video player in C who read files on local and distant network.

  All works fine except for growing files (EG: a tv show currently in recording mode).

  Is there a way to force the current context to update duration ? A flag in AVFormatContext ?

• After a clean install of OpenCV via pip it throws an ImportError : DLL load failed

  20 juin 2017, par Kev1n91

  After installing OpenCV via pip on Windows 10 with:

  pip install opencv-python
  

  I can not import the module. When executing the command:

  import cv2
  

  I get the error:

  File "C:\ProgramData\Anaconda3\lib\site-packages\cv2__init__.py", line 7, in from . import cv2

  ImportError: DLL load failed:...

  If I look into the file throwing the code, it looks like the following:

  import sys
  import os
  
  # FFMPEG dll is not found on Windows without this
  os.environ["PATH"] += os.pathsep + os.path.dirname(os.path.realpath(__file__))
  
  from . import cv2
  sys.modules['cv2'] = cv2
  

  So I guess it is ffmpeg which is missing. Thus I installed ffmpeg like described here: http://www.wikihow.com/Install-FFmpeg-on-Windows

  Thus, ffmpeg is in my path. However, the error message still occurs. I also tried to install the ffmpeg via pip with

  pip install ffmpeg-normalize
  

  But this did not help either.

• ffmpeg send video to one process and audio to another

  20 juin 2017, par moo

  I'm using Sailfish OS (Linux), and have built ffmpeg with the hope of using the ffplay player. Video works fine, but audio doesn't work and I think ffplay would need to be patched to use libaudioresource, which is beyond my skills (others have verified the problem).

  However, the pulseaudio paplay and pacat commands work fine, so for example, I can do:

  ffmpeg -i file.mp4 -f wav - | paplay
  

  What I'm trying to achieve, is to send video to ffplay and audio to paplay, but the best solution I've found so far, is:

  ffmpeg -i file.mp4 -f avi - | tee >(ffplay -) >(ffmpeg -i - -f wav - | paplay) > /dev/null
  

  This is not very efficient though, and whilst it works, it breaks up frequently, and I was hoping there was a better way of achieving this, using -map 0:a and -map 0:v or FIFOs of something? Any suggestions much appreciated.

  Thanks

• Bash - Not able to replace the variable in ffmpeg subtitle

  20 juin 2017, par Steven Foong

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

  I use this command

  ffmpeg -i orgvideo.mp4 -vf subtitles="subtitle.ass" newvideo.mp4
  

  it work. So I plan to use bash shell script to automate the process.

  Everything is the script is working , but the ffmpeg command line wouldn't able to retrieve the subtitle variable.

  After google around, I found that my file name has special character and space, that cause my script not working. 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 having problem reading the subtitle file variable. Anyone can help?