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• Metal Gear Solid VP3 Easter Egg

  4 août 2011, par Multimedia Mike — Game Hacking

  Metal Gear Solid : The Twin Snakes for the Nintendo GameCube is very heavy on the cutscenes. Most of them are animated in real-time but there are a bunch of clips — normally of a more photo-realistic nature — that the developers needed to compress using a conventional video codec. What did they decide to use for this task ? On2 VP3 (forerunner of Theora) in a custom transport format. This is only the second game I have seen in the wild that uses pure On2 VP3 (first was a horse game). Reimar and I sorted out most of the details sometime ago. I sat down today and wrote a FFmpeg / Libav demuxer for the format, mostly to prove to myself that I still could.

  Things went pretty smoothly. We suspected that there was an integer field that indicated the frame rate, but 18 fps is a bit strange. I kept fixating on a header field that read 0x41F00000. Where have I seen that number before ? Oh, of course — it’s the number 30.0 expressed as an IEEE 32-bit float. The 4XM format pulled the same trick.

  Hexadecimal Easter Egg
  I know I finished the game years ago but I really can’t recall any of the clips present in the samples directory. The file mgs1-60.vp3 contains a computer screen granting the player access and illustrates this with a hexdump. It looks something like this :

  
  
  

  Funny, there are only 22 bytes on a line when there should be 32 according to the offsets. But, leave it to me to try to figure out what the file type is, regardless. I squinted and copied the first 22 bytes into a file :

   1F 8B 08 00   85 E2 17 38   00 03 EC 3A   0D 78 54 D5
   38 00 03 EC   3A 0D
  

  And the answer to the big question :

  $ file mgsfile
  mgsfile : gzip compressed data, from Unix, last modified : Wed Oct 27 22:43:33 1999
  

  A gzip’d file from 1999. I don’t know why I find this stuff so interesting, but I do. I guess it’s no more and less strange than writing playback systems like this.

• libavformat/mxfenc : add container duration and package name to primer pack

  22 mars 2015, par Mark Reid

  libavformat/mxfenc : add container duration and package name to primer pack
  Reviewed-by : Tomas Härdin <tomas.hardin@codemill.se>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/mxfenc.c
  • [DH] tests/ref/lavf/mxf
  • [DH] tests/ref/lavf/mxf_d10
  • [DH] tests/ref/lavf/mxf_opatom
  • [DH] tests/ref/seek/lavf-mxf_opatom

• How can I record my usb webcam to an mp4 format ? [duplicate]

  16 septembre 2020, par Todd Murphy

  I have been trying for hours to record my USB webcam to a .mp4 file format. The only format that works is .avi right now. I am on a RPi using video4linux2.

  


  This code does not work :

  


  ffmpeg -f video4linux2 -framerate 30 -s 1280x720 -i /dev/video0 /home/pi/videos/output.mp4


  


  When opening the file, it gives me an error in my video player. I also tried adding "-f mp4" but that does not work either. Please help. Thanks !