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• FFmpeg : Interpolation for Fade-In

  6 juillet 2017, par Sir Bad News

  I’m currently using the following to fade-in a short film.

  ffmpeg -i input.mp4 -filter:v fade=in:0:360 -c:v libx264 -preset:v slower -crf:v 24 -pix_fmt yuv420p output.mp4

  ---

  Everything works as expected ; however, the interpolation of the fade is not what I’m after (seems to be linear). I’d like to play around with exponential, cubic, sinusoidal, etc.

  Is there any way to achieve this with FFmpeg ? The visual material I’m working with is pure white and pure black, and the fade-in as it stands is too harsh ; I can see the material appear almost as soon as the fade starts as a result of the (apparently) linear progression. I’d like it to be more organic.

  Any help greatly appreciated.

• create mono and stereo stream in the same file with ffmpeg ?

  24 juillet 2017, par user2216280

  I have a film with 2 mono audio stream of avi file.

  I would like to create a third file, with one stereo stream from the 2 mono stream, and one mono stream, addition of the 2 monos audio source...
  here’s the code to make mono stream :

  ffmpeg -i input.avi-ac 1 mono.avi

  here’s the code to make an stereo stream from 2 mono stream :

  ffmpeg -i input.avi-filter_complex "[0:1][0:2] amerge=inputs=2" -c:a pcm_s16le output.avi

  How could I merge those 2codes to make one audio file with one stero track, and one mono track ?
  tiouss ! thanks in advance

• Writing an MP4 file on the Mac with OpenCV ffmpeg

  13 janvier 2015, par Sameer Parekh

  I am using OpenCV with ffmpeg on a mac to write video. I’ve been able to successfully write .avi files using the codec/fourcc code, FMP4. I would like to write .mp4 files, however. When I try to write an .mp4 file using fourcc FMP4 I get this error :

  [mp4 @ 0x100b4ec00] Tag FMP4/0x34504d46 incompatible with output codec id '13' ( [0][0][0])

  When I use AVC1 I get the following error :

  [libx264 @ 0x104003000] broken ffmpeg default settings detected
  
  [libx264 @ 0x104003000] use an encoding preset (e.g. -vpre medium)
  
  [libx264 @ 0x104003000] preset usage: -vpre <speed> -vpre <profile>
  
  [libx264 @ 0x104003000] speed presets are listed in x264 --help
  
  [libx264 @ 0x104003000] profile is optional; x264 defaults to high
  
  Could not open codec 'libx264': Unspecified error
  
  </profile></speed>

  Does anyone here know the right codec to use with OpenCV and ffmpeg to write to an MP4 container on the Mac ?

  If AVC1 is the right codec, how do I install ffmpeg + OpenCV correctly ? I did

  brew install gpac
  
  brew install ffmpeg
  
  brew install opencv

  The call I am using to open the videowriter :

  fourcc = cv2.cv.CV_FOURCC('A', 'V', 'C', '1')   
  
  video_out = cv2.VideoWriter(
  
      filename=output_filename,
  
      fourcc=fourcc,
  
      fps=video_fps,
  
      frameSize=(video_width,video_height),
  
      isColor=1)

  When I run x264 --help I get

  % x264 --help
  
  x264 core:125
  
  Syntax: x264 [options] -o outfile infile
  
  
  
  Infile can be raw (in which case resolution is required),
  
    or YUV4MPEG (*.y4m),
  
    or Avisynth if compiled with support (no).
  
    or libav* formats if compiled with lavf support (no) or ffms support (no).
  
  Outfile type is selected by filename:
  
   .264 -> Raw bytestream
  
   .mkv -> Matroska
  
   .flv -> Flash Video
  
   .mp4 -> MP4 if compiled with GPAC support (no)
  
  Output bit depth: 8 (configured at compile time)
  
  
  
  Options:
  
  
  
    -h, --help                  List basic options
  
        --longhelp              List more options
  
        --fullhelp              List all options
  
  
  
  Example usage:
  
  
  
        Constant quality mode:
  
              x264 --crf 24 -o <output> <input />
  
  
  
        Two-pass with a bitrate of 1000kbps:
  
              x264 --pass 1 --bitrate 1000 -o <output> <input />
  
              x264 --pass 2 --bitrate 1000 -o <output> <input />
  
  
  
        Lossless:
  
              x264 --qp 0 -o <output> <input />
  
  
  
        Maximum PSNR at the cost of speed and visual quality:
  
              x264 --preset placebo --tune psnr -o <output> <input />
  
  
  
        Constant bitrate at 1000kbps with a 2 second-buffer:
  
              x264 --vbv-bufsize 2000 --bitrate 1000 -o <output> <input />
  
  
  
  Presets:
  
  
  
        --profile <string>      Force the limits of an H.264 profile
  
                                    Overrides all settings.
  
                                    - baseline,main,high,high10,high422,high444
  
        --preset <string>       Use a preset to select encoding settings [medium]
  
                                    Overridden by user settings.
  
                                    - ultrafast,superfast,veryfast,faster,fast
  
                                    - medium,slow,slower,veryslow,placebo
  
        --tune <string>         Tune the settings for a particular type of source
  
                                or situation
  
                                    Overridden by user settings.
  
                                    Multiple tunings are separated by commas.
  
                                    Only one psy tuning can be used at a time.
  
                                    - psy tunings: film,animation,grain,
  
                                                   stillimage,psnr,ssim
  
                                    - other tunings: fastdecode,zerolatency
  
  
  
  Frame-type options:
  
  
  
    -I, --keyint <integer or="or"> Maximum GOP size [250]
  
        --tff                   Enable interlaced mode (top field first)
  
        --bff                   Enable interlaced mode (bottom field first)
  
        --pulldown <string>     Use soft pulldown to change frame rate
  
                                    - none, 22, 32, 64, double, triple, euro (requires cfr input)
  
  
  
  Ratecontrol:
  
  
  
    -B, --bitrate <integer>     Set bitrate (kbit/s)
  
        --crf <float>           Quality-based VBR (0-51) [23.0]
  
        --vbv-maxrate <integer> Max local bitrate (kbit/s) [0]
  
        --vbv-bufsize <integer> Set size of the VBV buffer (kbit) [0]
  
    -p, --pass <integer>        Enable multipass ratecontrol
  
                                    - 1: First pass, creates stats file
  
                                    - 2: Last pass, does not overwrite stats file
  
  
  
  Input/Output:
  
  
  
    -o, --output <string>       Specify output file
  
        --sar width:height      Specify Sample Aspect Ratio
  
        --fps   Specify framerate
  
        --seek <integer>        First frame to encode
  
        --frames <integer>      Maximum number of frames to encode
  
        --level <string>        Specify level (as defined by Annex A)
  
        --quiet                 Quiet Mode
  
  
  
  Filtering:
  
  
  
        --vf, --video-filter <filter0>/<filter1>/... Apply video filtering to the input file
  
  
  
        Filter options may be specified in <filter>:<option>=<value> format.
  
  
  
        Available filters:
  
        crop:left,top,right,bottom
  
        select_every:step,offset1[,...]
  
  </value></option></filter></filter1></filter0></string></integer></integer></string></integer></integer></integer></float></integer></string></integer></string></string></string></output></output></output></output></output></output>

  Thanks,
   s