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• How to extract good quality frames from a video and save them without compression ?

  13 août 2019, par Albert

  How can I use ffmpeg and only extract the frames that does not have artifacts (e.g. compression artifacts) from a video and save them with good quality in jpeg format .

• ffmpeg won't save the file when executed from a php page

  6 septembre 2015, par Tayax

  I wrote few lines of codes today to create an video from an image with ffmpeg.

  the command works well directly on my server and the file is saved at the good place, but when running it from PHP, the process goes, but the file won’t save for some reason.

  Here is the code I use :

  $ffmpegcmd= "/usr/bin/ffmpeg -loop 1 -y -i /home/mysite/www/forwork/simpletext.jpg -c:v libx264 -t 30 -pix_fmt yuv420p /home/mysite/www/forwork/movie.avi 2>&1";
  
  exec($ffmpegcmd, $output);  
  
  print_r($output);

  And here is the answer I get :

  Array ( [0] => ffmpeg version git-2015-09-06-db18b3d Copyright (c) 2000-2015 the FFmpeg developers 
  
  [1] => built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-16) 
  
  [2] => configuration: --prefix=/usr/ffmpeg_build --extra-cflags=-I/usr/ffmpeg_build/include --extra-ldflags=-L/usr/ffmpeg_build/lib --bindir=/usr/bin --pkg-config-flags=--static --enable-gpl --enable-nonfree --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 
  
  [3] => libavutil 55. 0.100 / 55. 0.100 
  
  [4] => libavcodec 57. 0.100 / 57. 0.100 
  
  [5] => libavformat 57. 0.100 / 57. 0.100 
  
  [6] => libavdevice 57. 0.100 / 57. 0.100 
  
  [7] => libavfilter 6. 0.100 / 6. 0.100 
  
  [8] => libswscale 4. 0.100 / 4. 0.100 
  
  [9] => libswresample 2. 0.100 / 2. 0.100 
  
  [10] => libpostproc 54. 0.100 / 54. 0.100 
  
  [11] => Input #0, image2, from '/home/mysite/www/forwork/simpletext.jpg': 
  
  [12] => Duration: 00:00:00.04, start: 0.000000, bitrate: 10414 kb/s 
  
  [13] => Stream #0:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1280x720 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc 
  
  [14] => /home/mysite/www/forwork/movie.avi: Permission denied )

  I chmod the forwork directory to 755 but it won’t change anything.

  help troubleshooting this would be greatly appreciate. Thanks

• FFMPEG - How to save audio stream detached from video to file whithout transcoding

  15 septembre 2015, par Tony Than

  I try to use fwrite() to save audio stream. But, generated file can not be opened.
  At the same time, I also try to use av_frame_write() to write packet. But, it can not write.
  Please help me with this problem. How to write audio stream without transcoding....

  /* open the input file with generic avformat function */
  
  err = avformat_open_input(input_format_context, filename, NULL, NULL);
  
  if (err < 0) {
  
      return err;
  
  }
  
  
  
  /* If not enough info to get the stream parameters, we decode the
  
     first frames to get it. (used in mpeg case for example) */
  
  ret = avformat_find_stream_info(*input_format_context, 0);
  
  if (ret < 0) {
  
      av_log(NULL, AV_LOG_FATAL, "%s: could not find codec parameters\n", filename);
  
      return ret;
  
  }
  
  
  
  /* dump the file content */
  
  av_dump_format(*input_format_context, 0, filename, 0);
  
  
  
  for (size_t i = 0; i < (*input_format_context)->nb_streams; i++) {
  
      AVStream *st = (*input_format_context)->streams[i];
  
      if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          FILE *file = NULL;
  
          file = fopen("C:\\Users\\MyPC\\Downloads\\test.aac", "wb");
  
          AVPacket reading_packet;
  
          av_init_packet(&reading_packet);
  
          while (av_read_frame(*input_format_context, &reading_packet) == 0) {
  
              if (reading_packet.stream_index == (int) i) {
  
              fwrite(reading_packet.data, 1, reading_packet.size, file);
  
              }
  
              av_free_packet(&reading_packet);   
  
          }
  
          fclose(file);
  
  
  
          return 0;
  
      }
  
  }