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• Cracking Aztec Game Audio

  7 juin 2011, par Multimedia Mike — Game Hacking

  Here’s a mild multimedia-related reverse engineering challenge for you. It’s pretty straightforward for those skilled in the art.

  The Setup
  One side effect of running this ridiculously niche interest blog at the intersection of multimedia, reverse engineering, and game hacking is that people occasionally contact me for assistance on those very matters. So it was when one of my MobyGames peers asked if I can help to extract some music from a game called Aztec Wars. The game consists of 2 discs, each with a music.xbe file that contains multiple tunes and is hundreds of megabytes large.

  
  
  

  That’s all the data I received from the first email. At first I’m wondering what makes people think I have some magical insight into cracking these formats with such little information. Ordinarily, I would need to have the entire data file to work with and possibly the game binaries. But I didn’t want to ask him to upload hundreds of megabytes of data and I didn’t feel like downloading it ; commitment issues and all.

  But then I gathered a little confidence and remembered that the .xbe files are probably just Game Resource Archive Formats (GRAF) which are, traditionally, absurdly simple. I asked my colleague to send me a hexdump of the first kilobyte of one of the .xbe GRAFs ('hexdump -C -n 1024 music.xbe > file') as well as the total file size of the GRAF.

  The Hexdump
  The first music.xbe file is 192817376 bytes large. These are the first 1024 144 bytes (more than enough) :

  00000000  01 00 00 00 60 04 00 00  14 00 00 00 01 00 00 00  |....`...........|
  00000010  0d 00 00 00 48 00 00 00  94 39 63 01 1c a4 21 03  |....H....9c..¤ !.|
  00000020  7a d2 54 04 04 28 ad 05  d8 88 fd 06 d8 88 fd 06  |zÒT..(­.Ø.ý.Ø.ý.|
  00000030  2a 6e 46 08 2a 6e 46 08  2a 6e 46 08 2a 6e 46 08  |*nF.*nF.*nF.*nF.|
  00000040  50 13 2f 0a e0 28 7e 0b  52 49 46 46 44 39 63 01  |P./.à( .RIFFD9c.|
  00000050  57 41 56 45 66 6d 74 20  10 00 00 00 01 00 02 00  |WAVEfmt ........|
  00000060  44 ac 00 00 10 b1 02 00  04 00 10 00 64 61 74 61  |D¬...±......data|
  00000070  fc 13 63 01 00 00 00 00  00 00 00 00 00 00 00 00  |ü.c.............|
  00000080  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
  

  The Challenge
  Armed with only the information in the foregoing section, figure out a method for extracting all the audio files in that file and advise on their playback/conversion. Ideally, this method should require minimal effort from both you and the person on the other end of the conversation.

  The Resolution
  The reason I ask is because I came up with a solution but knew, deep down, that there must be a slightly easier way. How would you solve this ?

  The music files in question are now preserved on YouTube (until they see fit to remove them for one reason or another).

• playback speed of ffmpeg-stitched python video plots

  30 juin 2012, par user1211129

  I've been generating videos out of plots made with matplotlib using a line of ffmpeg code. The output is in .mp4 format. However, when I tried to heighten the resolution of each individual plot to dpi=800, the resultant video (at 140 MB) lags severely when played back with quicktime. Is there a way around this ? I do wonder, if the file's too large to play efficiently, why does a movie of 6 GB play flawlessly ?

• iPhone HTTP Streaming .m3u8 and .ts files - how to create using ffmpeg

  8 septembre 2013, par ChessDev

  I'm trying to get apple-validated http media streams using ffmpeg and am getting errors. Here are some error examples :

  WARNING : Playlist Content-Type is 'application/x-mpegurl', but should
  be one of 'application/vnd.apple.mpegurl', 'audio/x-mpegurl' or
  'audio/mpegurl'.

  WARNING : 258 samples (88.966 %) do not have timestamps in track 256
  (avc1). 4 : us2-1.ts
   

  WARNING : Media segment duration outside of expected duration by 47.733
   % (5.23 vs. 10.00 seconds, limit is 20 %). 40 : us2-19.ts
   

  Average segment duration: 10.16 seconds
  
  Average segment bitrate: 320.12 kbit/s
  
  Average segment structural overhead: 175.89 kbit/s (54.94 %)
  
  
  
  Video codec: avc1
  
  Video resolution: 320x320 pixels
  
  Video frame rate: 29.72, 29.78, 29.82, 30.00, 29.64 fps
  
  Average video bitrate: 100.66 kbit/s
  
  H.264 profile: Baseline
  
  H.264 level: 3.0
  
  
  
  Audio codec: aac 
  
  Audio sample rate: 48000 Hz
  
  Average audio bitrate: 43.57 kbit/s

  ---

  Here is the end file I've been submitting : http://files.chesscomfiles.com/images_users/using/us2.m3u8

  Here is the file I used to create this : http://files.chesscomfiles.com/images_users/using/using-computers-1.mp4

  I've tried these commands, among others :

  ffmpeg -i using-computers-1.mp4 -f mpegts -acodec libfaac -ar 48000
  -ab 64k -s 320x320 -vcodec libx264 -vbsf h264_mp4toannexb -b 96k -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 5 -trellis 1 -refs 1 -coder 0 -me_range 16 -keyint_min 2 -sc_threshold 40 -i_qfactor 0.71 -bt 200k -maxrate 96k -bufsize 96k -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 -g 30 -async 2 us2.ts

  ffmpeg -i using-computers-1.mp4 -f mpegts -acodec libfaac -ar 48000
  -ab 64k -s 320x320 -vcodec libx264 -vbsf h264_mp4toannexb -b 96k -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 5 -trellis 1 -refs 1 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 200k -maxrate 96k -bufsize 96k -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 -g 30 -async 2 us1.ts

  ffmpeg -i using-computers-1.mp4 -vbsf h264_mp4toannexb -acodec copy -vcodec copy -f mpegts output.ts

  If someone can help me figure out what ffmpeg commands I should be running I'd really appreciate it !