Recherche avancée

Sur d’autres sites (12387)

• Movie from PNGs using FFmpeg and Python - rgb24 vs yuv420p

  7 février 2016, par Eilam G

  I wrote a little Python program to grab a bunch of PNGs and render them into a movie using the FFmpeg command line. The PNGs are read into [X*Y*3] numpy arrays (ignoring the alpha channel), new frames are added via interpolation, and the data is fed into FFmpeg as a pipe and saved as an mp4.

  The files play fine in VLC on Windows, but don’t work in iMovie on a Mac. I think it might have to do with most programs expecting H264 videos to be in the YUV420P color space, which my movies aren’t. I’ve tried changing the ffmpeg command -pix_fmt from rgb24 to yuv420p, but no go.

  Relevant Python code attached below.

  def init_vars(args):
  
      global log_file, file_names, command, num_int_frames, num_files, silent
  
  
  
      file_names = glob('./*.png')
  
      num_files = len(file_names)
  
  
  
      if args.log:
  
          log_file = 'bmmp.log'
  
      else:
  
          log_file = os.devnull
  
  
  
      silent = args.silent
  
  
  
      frames_per_second = args.fps
  
      wanted_movie_length = args.length
  
      movie_file_name = args.name + '.mp4'
  
  
  
      num_int_frames = round((frames_per_second * wanted_movie_length - 1) / (num_files - 1) - 1)
  
  
  
      if sys.platform == 'win32':
  
          ffmpeg_bin = 'ffmpeg.exe'
  
      else:
  
          ffmpeg_bin = 'ffmpeg'
  
  
  
      command = [ffmpeg_bin,
  
                 '-y', # (optional) overwrite output file if it exists
  
                 '-f', 'rawvideo',
  
                 '-vcodec','rawvideo',
  
                 '-s', '1280x720', # size of one frame
  
                 '-pix_fmt', 'rgb24',
  
                 '-r', str(frames_per_second), # frames per second
  
                 '-i', '-', # The input comes from a pipe
  
                 '-an', # Tells FFMPEG not to expect any audio
  
                 movie_file_name]

  Cheers,
  Eilam

• The duration of movie file recorded by AVAssetWriter is not correct

  1er mars 2016, par ideawu

  I am recording video files with AVAssetWriter combining with AVCaptureVideoDataOutputSampleBufferDelegate. So I can take control over every frame the camara gives in the method :

  - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
  
      double time = CMTimeGetSeconds(CMSampleBufferGetPresentationTimeStamp(sampleBuffer));
  
      NSLog(@"%f", time);
  
      [_videoInput appendSampleBuffer:sampleBuffer];
  
  }

  So I am so sure how many samples have been written to AVAssetWriter via AVAssetWriterInput, and I know exactly the start time and end time of the samples being written. The duration is calculated by end_time - start_time. Say the duration calculated in the video capture programm is 0.5 second.

  I get the .mov/.mp4 file on disk, inspected with ffmpeg -i, it shows a very different duration.

  ffmpeg -i m003.mp4 2>&1 | grep Dura
  
    Duration: 00:00:01.37, start: 0.836667, bitrate: 95 kb/s

  The movie file show a duration of 1.37 seconds, which it’s quite different with the EXACT duration 0.5.

  Does any one knows the reason ?

• ffmpeg : unable to cut avi movie

  10 mars 2016, par ird

  I am using ffmpeg to cut video file :

  ffmpeg -<inputfile> -ss 00:00:00 -t 00:00:30 <outputfile>
  
  </outputfile></inputfile>

  It’s OK for different file formats exclude *.avi format. For avi movies ffmpeg shows that video is truncated, but output file contains full video (without truncating).
  Does anybody know possible ways for problem troubleshooting ?

  Here converting command output for avi file :

  FFmpeg version SVN-r26402, Copyright (c) 2000-2011 the FFmpeg developers
  
    built on Feb  1 2011 02:54:36 with gcc 4.4.5
  
    configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab
  
    libavutil     50.36. 0 / 50.36. 0
  
    libavcore      0.16. 1 /  0.16. 1
  
    libavcodec    52.108. 0 / 52.108. 0
  
    libavformat   52.93. 0 / 52.93. 0
  
    libavdevice   52. 2. 3 / 52. 2. 3
  
    libavfilter    1.74. 0 /  1.74. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  [mpeg4 @ 0x91e7e10] Invalid and inefficient vfw-avi packed B frames detected
  
  
  
  Seems stream 0 codec frame rate differs from container frame rate: 30000.00 (30000/1) -> 25.00 (25/1)
  
  Input #0, avi, from '/home/mightymeeting/Videos/tam-19.avi':
  
    Duration: 00:04:43.32, start: 0.000000, bitrate: 564 kb/s
  
      Stream #0.0: Video: mpeg4, yuv420p, 352x208 [PAR 1:1 DAR 22:13], 25 fps, 25 tbr, 25 tbn, 30k tbc
  
      Stream #0.1: Audio: mp3, 32000 Hz, 2 channels, s16, 80 kb/s
  
  [buffer @ 0x91e6ed0] w:352 h:208 pixfmt:yuv420p
  
  Output #0, avi, to 'out.avi':
  
    Metadata:
  
      ISFT            : Lavf52.93.0
  
      Stream #0.0: Video: mpeg4, yuv420p, 352x208 [PAR 1:1 DAR 22:13], q=2-31, 200 kb/s, 25 tbn, 25 tbc
  
      Stream #0.1: Audio: mp2, 32000 Hz, 2 channels, s16, 64 kb/s
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
    Stream #0.1 -> #0.1
  
  Press [q] to stop encoding
  
  [mpeg4 @ 0x91e7e10] Invalid and inefficient vfw-avi packed B frames detected
  
  frame= 7082 fps=999 q=2.0 Lsize=    7513kB time=30.02 bitrate=2049.8kbits/s dup=0 drop=1    
  
  video:7079kB audio:235kB global headers:0kB muxing overhead 2.718192%