Recherche avancée

Sur d’autres sites (5348)

• 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.

• Replace Special Characters In Batch-File Variable Feeding ffmpeg program

  14 janvier 2019, par whereswaller

  I am attempting to write a batch-file that leverages ffmpeg.exe to convert all files in a folder structure to mp3 format (specifically 128 KBps).

  My batch-file is presently unable to process filenames (constructed by concatenating the %_SOURCE% and %%~F variables) containing certain special characters generating the following errors :

  No such file or directory

  • … ellipsis sign
  • – en dash
  • — em dash
  • − minus sign

  Invalid argument

  • ‘ and ’ curved single quotation marks
  • “ and ” curved double quotation marks

  Invalid argument (yet sometimes passes depending on where symbol is in the filename, for example, seems to work if placed between the n and t of Dont in C:\Users\Test\Documents\Input\Peter Bjorn And John - I Know You Dont Love Me.mp3)

  • - hyphen
  • ! exclamation mark
  • ~ tilde
  • ' non-curved single quotation mark
  • = equals sign
  • + plus sign
  • % percentage sign
  • ( open bracket

  How can I modify my batch-file script so that the %%~F variable escapes these characters correctly ?

  Example current filename input : C:\Users\Test\Documents\Input\Peter Bjorn And John - I Know You Don't Love Me.mp3

  Example desired filename input : C:\Users\Test\Documents\Input\Peter Bjorn And John - I Know You Don"^'"t Love Me.mp3

  Script (see line beginning C:\ffmpeg\bin\ffmpeg.exe) :

  @echo off
  
  setlocal EnableExtensions DisableDelayedExpansion
  
  
  
  rem // Define constants here:
  
  set "_SOURCE=C:\Users\Test\Documents\Input" & rem // (absolute source path)
  
  set "_TARGET=C:\Users\Test\Documents\Output"  & rem // (absolute target path)
  
  set "_PATTERN=*.*" & rem // (pure file pattern for input files)
  
  set "_FILEEXT=.mp3"   & rem // (pure file extension of output files)
  
  
  
  pushd "%_TARGET%" || exit /B 1
  
  for /F "delims=" %%F in ('
  
      cd /D "%_SOURCE%" ^&^& ^(rem/ list but do not copy: ^
  
          ^& xcopy /L /S /Y /I ".\%_PATTERN%" "%_TARGET%" ^
  
          ^| find ".\" ^& rem/ remove summary line;
  
      ^)
  
  ') do (
  
      2> nul mkdir "%%~dpF."
  
  
  
      rem // Set up the correct `ffmpeg` command line here:
  
      set "FFREPORT=file=C\:\\Users\\Test\\Documents\\Output\\ffreport-%%~F.log:level=32"
  
      "C:\ffmpeg\bin\ffmpeg.exe" -report -n -i "%_SOURCE%\%%~F" -vn -c:a libmp3lame -b:a 128k "%%~dpnF%_FILEEXT%"
  
      if not errorlevel 1  if exist "%%~dpnF%_FILEEXT%" del /f /q "%_SOURCE%\%%~F"
  
  
  
  )
  
  popd
  
  
  
  endlocal
  
  pause

• Damaged h264 stream not working with ffmpeg but working with vlc or mplayer

  15 avril 2013, par gregoiregentil

  I have a h264 file, coming from an rtsp stream, that is slightly damaged. Some frames are altered.

  ffmpeg reports :

  ffmpeg -i stream.mpg 
  
  ffmpeg version 0.8.6-4:0.8.6-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav developers
  
    built on Apr  2 2013 17:00:59 with gcc 4.6.3
  
  *** THIS PROGRAM IS DEPRECATED ***
  
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  
  
  
  Seems stream 0 codec frame rate differs from container frame rate: 180000.00 (180000/1) -> 90000.00 (180000/2)
  
  Input #0, mpegts, from 'a.mpg':
  
    Duration: 00:03:18.84, start: 93370.745522, bitrate: 2121 kb/s
  
    Program 1 
  
      Stream #0.0[0x44](): Video: h264 (Baseline), yuv420p, 640x480, 90k tbr, 90k tbn, 180k tbc
  
  At least one output file must be specified

  I can play the file with VLC or mplayer. Obviously, the damaged frames are "kind of blurred" but it's working. mplayer reports :

  mplayer stream.mpg
  
  MPlayer2 UNKNOWN (C) 2000-2011 MPlayer Team
  
  mplayer: could not connect to socket
  
  mplayer: No such file or directory
  
  Failed to open LIRC support. You will not be able to use your remote control.
  
  
  
  Playing stream.mpg.
  
  Detected file format: MPEG-2 transport stream format (libavformat)
  
  [lavf] stream 0: video (h264), -vid 0
  
  LAVF: Program 1 
  
  VIDEO:  [H264]  640x480  0bpp  90000.000 fps    0.0 kbps ( 0.0 kbyte/s)
  
  Load subtitles in .
  
  [ass] auto-open
  
  ==========================================================================
  
  Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
  
  Asking decoder to use 2 threads if supported.
  
  Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
  
  ==========================================================================
  
  Audio: no sound
  
  Starting playback...
  
  V:   0.0   0/  0 ??% ??% ??,?% 0 0 
  
  Movie-Aspect is undefined - no prescaling applied.
  
  VO: [xv] 640x480 => 640x480 Planar YV12 
  
  V:93370.7   0/  0 ??% ??% ??,?% 0 0 
  
  No pts value from demuxer to use for frame!
  
  Video pts after filters MISSING
  
  V:93370.7   0/  0 ??% ??% ??,?% 0 0 
  
  No pts value from demuxer to use for frame!
  
  Video pts after filters MISSING
  
  V:93370.7   0/  0 ??% ??% ??,?% 0 0 
  
  No pts value from demuxer to use for frame!
  
  Video pts after filters MISSING
  
  V:93370.7   0/  0 ??% ??% ??,?% 0 0 
  
  No pts value from demuxer to use for frame!
  
  Video pts after filters MISSING
  
  V:93370.7   0/  0 ??% ??% ??,?% 0 0 
  
  No pts value from demuxer to use for frame!
  
  Video pts after filters MISSING
  
  V:93370.7   0/  0 ??% ??% ??,?% 0 0 
  
  No pts value from demuxer to use for frame!
  
  Video pts after filters MISSING
  
  V:93370.7   0/  0 ??% ??% ??,?% 0 0 
  
  No pts value from demuxer to use for frame!

  When I try to re-encode the file with :

  ffmpeg -i stream.mpg -fflags +genpts -an -vcodec mpeg4 -r 65535/2733 stream.mp4

  ffmpeg seems to jump over the altered frames. The length of stream.mp4 << length of stream.mpg

  How could I fix this problem, i.e. having ffmpeg to output something similar to what mplayer and vlc output ?