Newest 'ffmpeg' Questions - Stack Overflow

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• FFmpeg - Convert MP4 to Webm very slow

  26 avril 2017, par Luzwitz

  I need convert MP4 to webm with ffmpeg. So, i use :

  ffmpeg -i input.mp4 -c:v libvpx -crf 10 -b:v 1M -c:a libvorbis output.webm
  

  But it's very long.

  Is there faster ?

• ffmpeg avformat_open_input with custom stream object

  26 avril 2017, par trigger_death

  I'm currently trying to write a custom SoundFileReader for SFML using ffmpeg's libraries. The only thing I have available to use with avcodec and avformat is the class InputStream below which is part of SFML. I've looked at avformat_open_input and AVIOContext and I learned how to use custom stream with a buffer but how do I create an AVIOContext that works with the custom read, seek, and lseek functions?

  class InputStream {
      int64_t getSize()
      int64_t read(void* data, int64_t size);
      int64_t seek(int64_t position);
      int64_t tell(); // Gets the stream position
  };
  

• OpenCV python, reading video frames from ffmpeg pipe

  26 avril 2017, par codefame

  I'm trying to use ffmpeg to pipe a video to opencv frame by frame.

  Structure:

  1. main script calls threaded process to obtain video & pipe video to image2pipe
  2. main script calls threaded process to read stdout for frame info
  3. main script calls function to continuously check for frame data

  Video Capture Function:

  def recordstream(self):
      global pipe
      # start video capture process
      pipe = Popen([VIDEO_CAPTURE_SOURCE + " | ffmpeg -i pipe:0 -pix_fmt bgr24 -r 1 -f image2pipe -"], stdout = PIPE, bufsize=10**8, shell=True)
  

  This ffmpeg code seems to work just fine when the capture source was tested with a single frame, but it doesn't work using the video stream.

  Buffer Read Function:

  def rawImage(self):
      global pipe, raw_image
      raw_image = pipe.stdout.read() # save output for opencv
  

  I gave this its own thread because it seems to be a blocking function.

  OpenCV Function:

  def checkframe(self):
      time.sleep(2)
      global raw_image
  
      while(True):
          array = numpy.frombuffer(raw_image, dtype='uint8')
          frame = cv2.imdecode(array, 1)
  
          if frame is None:
              print("Image not found")
          else:
              print("FOUND IMAGE")
              cv2.imshow(frame)
              if cv2.waitKey(1) & 0xFF == ord('q'):
                  break
  

  This function fails at frame = cv2.imdecode(array, 1) as the array seems to be empty.

  Error:

  !buf.empty() && buf.isContinuous() in function imdecode_
  

  I see lots of discussion around piping data from OpenCV to ffmpeg, but not much the other way around. What am I missing here?

  Thanks in advance.

• How to recompile ffmpeg in Ubuntu

  26 avril 2017, par David Page

  I installed ffmpeg in Ubuntu but in a wrong way--I compiled it with only --enable-libass. And now I can not use -crf option so I want to recompile it.

  According to this page I typed these command:

  rm -rf ~/ffmpeg_build ~/ffmpeg_sources~/bin/{ffmpeg,ffprobe,ffplay,ffserver,vsyasm,x264,x265,yasm,ytasm}
  

  then I started compile again:

  cd ~/ffmpeg_sources
  wget http://ffmpeg.org/releases/ffmpeg-snapshot.tar.bz2
  tar xjvf ffmpeg-snapshot.tar.bz2
  cd ffmpeg
  PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure \
    --prefix="$HOME/ffmpeg_build" \
    --pkg-config-flags="--static" \
    --extra-cflags="-I$HOME/ffmpeg_build/include" \
    --extra-ldflags="-L$HOME/ffmpeg_build/lib" \
    --bindir="$HOME/bin" \
    --enable-gpl \
    --enable-libass \
    --enable-libfdk-aac \
    --enable-libfreetype \
    --enable-libmp3lame \
    --enable-libopus \
    --enable-libtheora \
    --enable-libvorbis \
    --enable-libvpx \
    --enable-libx264 \
    --enable-libx265 \
    --enable-nonfree
  PATH="$HOME/bin:$PATH" make
  make install
  make distclean
  hash -r
  

  But when I type ffmpeg it still output:

  ffmpeg version N-77474-g11388b5 Copyright (c) 2000-2015 the FFmpeg developers
    built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04)
    configuration: --enable-libass
    libavutil      55. 11.100 / 55. 11.100
    libavcodec     57. 20.100 / 57. 20.100
    libavformat    57. 20.100 / 57. 20.100
    libavdevice    57.  0.100 / 57.  0.100
    libavfilter     6. 22.100 /  6. 22.100
    libswscale      4.  0.100 /  4.  0.100
    libswresample   2.  0.101 /  2.  0.101
  

  I am puzzled and how to recompile or remove ffmpeg in a right way?

• Incorrect syntax using FFmpeg

  25 avril 2017, par Halid Kyazim

  Hello guys i am tring to convert videos using FFmpeg...

  1. I moved ffmpeg.exe in same folder with upload.php

  2. I tryed this codes in upload.php:

     $randname = (rand(0,1000));
     $file_data=date("d-m-Y-H-i-s");
     $file_name=$file_data.$randname;
     move_uploaded_file($file_tmp,"vidconvert/".$file_name);
     exec (ffmpeg -i vidconvert/.$file_name videos/.$file_name.mp4);
     echo "Success";
     

  3. I want to get the file in vidconvert folder, and copy converted video to videos folder

  Note: when i check the vidconfert folder, the file is uploaded succesfully