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• JavaCV FFmpegFrameRecorder properties explanation needed

  29 décembre 2014, par Leron

  I’m using FFmpegFrameRecorder to get the video input from my webcam and record it into a video file. The problem is that I’m building my application using a few different demo source codes that I found and I use properties some of which are not completely clear to me.

  First, here is my code snippet :

  FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(FILENAME,  grabber.getImageWidth(),grabber.getImageHeight());
  
  
  
          recorder.setVideoCodec(13);
  
          recorder.setFormat("mp4");
  
          recorder.setPixelFormat(avutil.PIX_FMT_YUV420P);
  
          recorder.setFrameRate(30);
  
          recorder.setVideoBitrate(10 * 1024 * 1024);
  
  
  
          recorder.start();

  • setVideoCodec(13) - What is the meaning of this (13) how can I understand what actual codec stands behind any number ?
  • setPixelFormat - Just get this, don’t know what it’s doing in general
  • setFrameRate(30) - I think this should be pretty clear but still what is the logic behind what frame rate we choose (isn’t the high the better ?)
  • setVideoBitrate(10*1024*1024) - again almost no idea what this does and what’s the logic behind the numbers ?

  At the end I just want to mention one last problem that I get recording video like this. If the actual length of the video is let’s say 20secs. When I play the video file created from the program it runs significantly faster. Can’t tell if it’s exactly 2 times faster than it should be but in general if I record a 20sec video then it’s played for about 10secs. What may cause this and how can I fix it ?

• Add Win32 GDI-based screen grabbing

  2 avril 2014, par Calvin Walton

  Add Win32 GDI-based screen grabbing
  Based on original code by Christophe Gisquet in 2010, updated to work
  
  with current ffmpeg APIs.
  Supports grabbing a single window or an area of the screen, including
  
  support for multiple monitors (Windows does funky stuff with negative
  
  coordinates here).
  I’ve moved most of the configuration to AVOptions ; the input file name
  
  is now only the string "desktop", or "title=<windowname>" to select a
  
  single window. The AVOptions are the same as x11grab where possible.
  Code has been added to support a "show_region" mode, like x11grab, which
  
  will draw a rectangle on the screen around the area being captured.
  Instead of duplicating code for paletted image handling, I make use of
  
  the GDI API’s ability to output DIB (BMP) images, which can be run
  
  through ffmpeg’s existing BMP decoder.
  Signed-off-by : Calvin Walton <calvin.walton@kepstin.ca>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] Changelog
  • [DH] configure
  • [DH] doc/general.texi
  • [DH] doc/indevs.texi
  • [DH] libavdevice/Makefile
  • [DH] libavdevice/alldevices.c
  • [DH] libavdevice/gdigrab.c

• PAF demuxer and decoder

  21 mars 2014, par Paul B Mahol

  PAF demuxer and decoder
  Signed-off-by : Vittorio Giovara <vittorio.giovara@gmail.com>
  
  Signed-off-by : Luca Barbato <lu_zero@gentoo.org>
  

  • [DH] Changelog
  • [DH] doc/general.texi
  • [DH] libavcodec/Makefile
  • [DH] libavcodec/allcodecs.c
  • [DH] libavcodec/avcodec.h
  • [DH] libavcodec/codec_desc.c
  • [DH] libavcodec/paf.c
  • [DH] libavcodec/version.h
  • [DH] libavformat/Makefile
  • [DH] libavformat/allformats.c
  • [DH] libavformat/paf.c
  • [DH] libavformat/version.h