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• 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

• Fix min/max validation. Closes gh-666. Fixes #648

  20 mars 2013, par ekonijn

  Fix min/max validation. Closes gh-666. Fixes #648
  In 1.10.0, min/max validation was supported for input type="text",
  
  where min/max were interpreted as numbers.  This means min/max
  
  for date would not work : min="2012-02-13" was interpreted as min="Not a Number".
  In 1.11.0, min/max were no longer converted to numbers.  This means
  
  min/max for dates worked, but min/max for numbers failed :
  
  "50" < "150" < "1000" does not hold.
  For an example, see http://jsbin.com/awokex/3
  This commit makes the behaviour of min/max dependent on input type :
   * input type=text (or not type attribute) has numeric min/max, as in 1.10.0
  
   * input type=date has working min/max for type date ;
  
     on mobile browsers you also get a date picker,
  
     plus the browser may reject invalid dates before
  
     javascript gets a chance to complain.
  
   * input type=number or range get numeric min/max,
  
     plus numeric keypad or slider on mobile browsers,
  
     plus browser may reject invalid input before javascript
  
     gets a chance to complain
  Allowing use of min/max with type=number/range/date is important
  
  for mobile browsers, where the numeric keypad or date picker
  
  make the input much easier to use than a generic text input field.
  
  In this situation jquery-validate remains necessary to support
  
  older browsers that do not do input validation based on type
  
  and min/max.
  For situations where numeric input should be validated by jquery
  
  without giving the browser a chance to validate the input format,
  
  input type=text in combination with min/max can be used, as in 1.10.0.
  

• ffmpeg concatenate images in one image

  26 juillet 2016, par drlexa

  I use this to get frames from video and concatenate them in one image :

  ffmpeg -i output.mp4 -vf 'fps=2,tile=1000x1' out.jpg

  But there is a problem : I do not know number of frames that will be fetched. Here I hardcoded tile size 1000x1, but if there will be more than 1000 frames, then will be an error. Before starting ffmpeg I do not know actual size of tile.

  So I want use command like :

  ffmpeg -i output.mp4 -vf 'fps=2,tile=*x1' out.jpg

  That means : I want you to concatenate ALL images that will be fetched in one row, but I cannot use * as an argument for tile.

  Is there some way to solve my problem ?