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• Parsing The Clue Chronicles

  30 décembre 2018, par Multimedia Mike — Game Hacking

  A long time ago, I procured a 1999 game called Clue Chronicles : Fatal Illusion, based on the classic board game Clue, a.k.a. Cluedo. At the time, I was big into collecting old, unloved PC games so that I could research obscure multimedia formats.

  
  
  

  Surveying the 3 CD-ROMs contained in the box packaging revealed only Smacker (SMK) videos for full motion video which was nothing new to me or the multimedia hacking community at the time. Studying the mix of data formats present on the discs, I found a selection of straightforward formats such as WAV for audio and BMP for still images. I generally find myself more fascinated by how computer games are constructed rather than by playing them, and this mix of files has always triggered a strong “I could implement a new engine for this !” feeling in me, perhaps as part of the ScummVM project which already provides the core infrastructure for reimplementing engines for 2D adventure games.

  Tying all of the assets together is a custom high-level programming language. I have touched on this before in a blog post over a decade ago. The scripts are in a series of files bearing the extension .ini (usually reserved for configuration scripts, but we’ll let that slide). A representative sample of such a script can be found here :

  clue-chronicles-scarlet-1.txt

  What Is This Language ?
  At the time I first analyzed this language, I was still primarily a C/C++-minded programmer, with a decent amount of Perl experience as a high level language, and had just started to explore Python. I assessed this language to be “mildly object oriented with C++-type comments (‘//’) and reliant upon a number of implicit library functions”. Other people saw other properties. When I look at it nowadays, it reminds me a bit more of JavaScript than C++. I think it’s sort of a Rorschach test for programming languages.

  Strangely, I sort of had this fear that I would put a lot of effort into figuring out how to parse out the language only for someone to come along and point out that it’s a well-known yet academic language that already has a great deal of supporting code and libraries available as open source. Google for “spanish dolphins far side comic” for an illustration of the feeling this would leave me with.

  It doesn’t matter in the end. Even if such libraries exist, how easy would they be to integrate into something like ScummVM ? Time to focus on a workable approach to understanding and processing the format.

  Problem Scope
  So I set about to see if I can write a program to parse the language seen in these INI files. Some questions :

  1. How large is the corpus of data that I need to be sure to support ?
  2. What parsing approach should I take ?
  3. What is the exact language format ?
  4. Other hidden challenges ?

  To figure out how large the data corpus is, I counted all of the INI files on all of the discs. There are 138 unique INI files between the 3 discs. However, there are 146 unique INI files after installation. This leads to a hidden challenge described a bit later.

  What parsing approach should I take ? I worried a bit too much that I might not be doing this the “right” way. I’m trying to ignore doubts like this, like how “SQL Shame” blocked me on a task for a little while a few years ago as I concerned myself that I might not be using the purest, most elegant approach to the problem. I know I covered language parsing a lot time ago in university computer science education and there is a lot of academic literature to the matter. But sometimes, you just have to charge in and experiment and prototype and see what falls out. In doing so, I expect to have a better understanding of the problems that need to solved and the right questions to ask, not unlike that time that I wrote a continuous integration system from scratch because I didn’t actually know that “continuous integration” was the keyword I needed.

  Next, what is the exact language format ? I realized that parsing the language isn’t the first and foremost problem here– I need to know exactly what the language is. I need to know what the grammar are keywords are. In essence, I need to reverse engineer the language before I write a proper parser for it. I guess that fits in nicely with the historical aim of this blog (reverse engineering).

  Now, about the hidden challenges– I mentioned that there are 8 more INI files after the game installs itself. Okay, so what’s the big deal ? For some reason, all of the INI files are in plaintext on the CD-ROM but get compressed (apparently, according to file size ratios) when installed to the hard drive. This includes those 8 extra INI files. I thought to look inside the CAB installation archive file on the CD-ROM and the files were there… but all in compressed form. I suspect that one of the files forms the “root” of the program and is the launching point for the game.

  Parsing Approach
  I took a stab at parsing an INI file. My approach was to first perform lexical analysis on the file and create a list of 4 types : symbols, numbers, strings, and language elements ([]{}()=., :). Apparently, this is the kind of thing that Lex/Flex are good at. This prototyping tool is written in Python, but when I port this to ScummVM, it might be useful to call upon the services of Lex/Flex, or another lexical analyzer, for there are many. I have a feeling it will be easier to use better tools when I understand the full structure of the language based on the data available.
  
  The purpose of this tool is to explore all the possibilities of the existing corpus of INI files. To that end, I ran all 138 of the plaintext files through it, collected all of the symbols, and massaged the results, assuming that the symbols that occurred most frequently are probably core language features. These are all the symbols which occur more than 1000 times among all the scripts :

     6248 false
     5734 looping
     4390 scripts
     3877 layer
     3423 sequentialscript
     3408 setactive
     3360 file
     3257 thescreen
     3239 true
     3008 autoplay
     2914 offset
     2599 transparent
     2441 text
     2361 caption
     2276 add
     2205 ge
     2197 smackanimation
     2196 graphicscript
     2196 graphic
     1977 setstate
     1642 state
     1611 skippable
     1576 desc
     1413 delayscript
     1298 script
     1267 seconds
     1019 rect
  

  About That Compression
  I have sorted out at least these few details of the compression :

  bytes 0-3    "COMP" (a pretty strong sign that this is, in fact, compressed data)
  bytes 4-11   unknown
  bytes 12-15  size of uncompressed data
  bytes 16-19  size of compressed data (filesize - 20)
  bytes 20-    compressed payload
  

  The compression ratios are on the same order of gzip. I was hoping that it was stock zlib data. However, I have been unable to prove this. I wrote a Python script that scrubbed through the first 100 bytes of payload data and tried to get Python’s zlib.decompress to initialize– no luck. It’s frustrating to know that I’ll have to reverse engineer a compression algorithm that deals with just 8 total text files if I want to see this effort through to fruition.

  Update, January 15, 2019
  Some folks expressed interest in trying to sort out the details of the compression format. So I have posted a followup in which I post some samples and go into deeper details about things I have tried :

  Reverse Engineering Clue Chronicles Compression

  The post Parsing The Clue Chronicles first appeared on Breaking Eggs And Making Omelettes.

• FFMPEG Incorrect Stream Index Matching with -var_stream_map

  28 décembre 2018, par Hugo

  I am using a bash script to run an FFMPEG command to turn an input file called Awoo.mkv into three HLS playlists each with a different resolution, video and audio bitrate.

  This is the script :

  name=gw
  
  
  
  rm /tmp/hls/*
  
  
  
  ./ffmpeg -y \
  
      -stream_loop -1 -re \
  
      -i Awoo.mkv \
  
      -b:v:0 4000k -b:a:0 512k -s:0 1920x1080 -r:0 30 -g:0 90 -preset:0 superfast -tune:0 zerolatency -profile:v:0 high -level:v:0 4 \
  
      -b:v:1 2500k -b:a:1 256k -s:1 1280x720 -r:1 30 -g:1 90 -preset:1 superfast -tune:1 zerolatency -profile:v:1 high -level:v:1 4 \
  
      -b:v:2 800k -b:a:2 255k -s:2 960x540 -r:2 30 -g:2 90 -preset:2 superfast -tune:2 zerolatency -profile:v:2 high -level:v:2 4 \
  
      -hls_time 6 \
  
      -hls_list_size 2 \
  
      -hls_flags delete_segments \
  
      -map 0:v -map 0:a -map 0:v -map 0:a -map 0:v -map 0:a \
  
      -var_stream_map "v:0,a:0 v:1,a:1 v:2,a:2" \
  
      -f hls -master_pl_name "${name}.m3u8" \
  
      -hls_segment_filename "/tmp/hls/${name}_-%d-%v.ts" \
  
      "/tmp/hls/${name}_%v.m3u8"

  This almost works great, but the output is slightly off...

  If you look at these two lines :

  -b:v:1 2500k -b:a:1 256k -s:1 1280x720 -r:1 30 -g:1 90 -preset:1 superfast -tune:1 zerolatency -profile:v:1 high -level:v:1 4 \
  
  -b:v:2 800k -b:a:2 255k -s:2 960x540 -r:2 30 -g:2 90 -preset:2 superfast -tune:2 zerolatency -profile:v:2 high -level:v:2 4 \

  A resolution of 1280x720 should have a bitrate of 2500k, a resolution of 960x540 should have a bitrate of 800k.

  This is the relevant output from FFMPEG :

  Stream #0:2(und): Video: h264 (libx264), yuv420p(progressive), 960x540 [SAR 1:1 DAR 16:9], q=-1--1, 2500 kb/s, 30 fps, 90k tbn, 30 tbc (default)
  
  Metadata:
  
    CREATION_TIME   : 2017-01-27 05:02:53
  
    LANGUAGE        : und
  
    HANDLER_NAME    : VideoHandler
  
    DURATION        : 00:02:24.310000000
  
    encoder         : Lavc58.18.100 libx264
  
  Side data:
  
    cpb: bitrate max/min/avg: 0/0/2500000 buffer size: 0 vbv_delay: -1
  
  Stream #0:3(eng): Audio: aac (LC), 44100 Hz, stereo, fltp, 256 kb/s (default)
  
  Metadata:
  
    LANGUAGE        : eng
  
    DURATION        : 00:02:24.348000000
  
    encoder         : Lavc58.18.100 aac
  
  Stream #0:4(und): Video: h264 (libx264), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 800 kb/s, 29 fps, 90k tbn, 29 tbc (default)
  
  Metadata:
  
    CREATION_TIME   : 2017-01-27 05:02:53
  
    LANGUAGE        : und
  
    HANDLER_NAME    : VideoHandler
  
    DURATION        : 00:02:24.310000000
  
    encoder         : Lavc58.18.100 libx264
  
  Side data:
  
    cpb: bitrate max/min/avg: 0/0/800000 buffer size: 0 vbv_delay: -1
  
  Stream #0:5(eng): Audio: aac (LC), 44100 Hz, stereo, fltp, 255 kb/s (default)
  
  Metadata:
  
    LANGUAGE        : eng
  
    DURATION        : 00:02:24.348000000
  
    encoder         : Lavc58.18.100 aac

  Stream #0:2 is given the wrong resolution of 960x540, and therefore also the wrong bitrate of 2500. This should be the resolution of 1280x720, but this is below matched with the bitrate of 800.

  From what I know, the resolutions are showing in the wrong order, if 720 was first and 540 after then everything would match up fine. I’m not sure what’s causing this, I am new to the -var_stream_map.

  If it is relevant, the entire output from FFMPEG is below :

  ffmpeg version 4.0.3-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  
    configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg
  
    libavutil      56. 14.100 / 56. 14.100
  
    libavcodec     58. 18.100 / 58. 18.100
  
    libavformat    58. 12.100 / 58. 12.100
  
    libavdevice    58.  3.100 / 58.  3.100
  
    libavfilter     7. 16.100 /  7. 16.100
  
    libswscale      5.  1.100 /  5.  1.100
  
    libswresample   3.  1.100 /  3.  1.100
  
    libpostproc    55.  1.100 / 55.  1.100
  
  Input #0, matroska,webm, from 'Awoo.mkv':
  
    Metadata:
  
      COMPATIBLE_BRANDS: iso6avc1mp41
  
      MAJOR_BRAND     : dash
  
      MINOR_VERSION   : 0
  
      ENCODER         : Lavf56.40.101
  
    Duration: 00:02:24.35, start: 0.000000, bitrate: 1114 kb/s
  
      Stream #0:0(und): Video: h264 (Main), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], 29 fps, 29 tbr, 1k tbn, 58 tbc (default)
  
      Metadata:
  
        CREATION_TIME   : 2017-01-27 05:02:53
  
        LANGUAGE        : und
  
        HANDLER_NAME    : VideoHandler
  
        DURATION        : 00:02:24.310000000
  
      Stream #0:1(eng): Audio: vorbis, 44100 Hz, stereo, fltp (default)
  
      Metadata:
  
        LANGUAGE        : eng
  
        DURATION        : 00:02:24.348000000
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  
    Stream #0:1 -> #0:1 (vorbis (native) -> aac (native))
  
    Stream #0:0 -> #0:2 (h264 (native) -> h264 (libx264))
  
    Stream #0:1 -> #0:3 (vorbis (native) -> aac (native))
  
    Stream #0:0 -> #0:4 (h264 (native) -> h264 (libx264))
  
    Stream #0:1 -> #0:5 (vorbis (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  [libx264 @ 0x664d1c0] using SAR=1/1
  
  [libx264 @ 0x664d1c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x664d1c0] profile High, level 4.0, 4:2:0, 8-bit
  
  [libx264 @ 0x664d1c0] 264 - core 157 r2935 545de2f - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x3 me=dia subme=1 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=4 lookahead_threads=4 sliced_threads=1 slices=4 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=1 keyint=90 keyint_min=9 scenecut=40 intra_refresh=0 rc=abr mbtree=0 bitrate=4000 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  [libx264 @ 0x664f080] using SAR=1/1
  
  [libx264 @ 0x664f080] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x664f080] profile High, level 4.0, 4:2:0, 8-bit
  
  [libx264 @ 0x664f080] 264 - core 157 r2935 545de2f - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x3 me=dia subme=1 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=4 lookahead_threads=4 sliced_threads=1 slices=4 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=1 keyint=90 keyint_min=9 scenecut=40 intra_refresh=0 rc=abr mbtree=0 bitrate=2500 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  [libx264 @ 0x6680b80] using SAR=1/1
  
  [libx264 @ 0x6680b80] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x6680b80] profile High, level 4.0, 4:2:0, 8-bit
  
  [libx264 @ 0x6680b80] 264 - core 157 r2935 545de2f - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=abr mbtree=1 bitrate=800 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  [hls @ 0x6650000] Opening '/tmp/hls/gw_-0-0.ts' for writing
  
  [hls @ 0x6650000] Opening '/tmp/hls/gw_-0-1.ts' for writing
  
  [hls @ 0x6650000] Opening '/tmp/hls/gw_-0-2.ts' for writing
  
  Output #0, hls, to '/tmp/hls/gw_%v.m3u8':
  
    Metadata:
  
      COMPATIBLE_BRANDS: iso6avc1mp41
  
      MAJOR_BRAND     : dash
  
      MINOR_VERSION   : 0
  
      encoder         : Lavf58.12.100
  
      Stream #0:0(und): Video: h264 (libx264), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 4000 kb/s, 30 fps, 90k tbn, 30 tbc (default)
  
      Metadata:
  
        CREATION_TIME   : 2017-01-27 05:02:53
  
        LANGUAGE        : und
  
        HANDLER_NAME    : VideoHandler
  
        DURATION        : 00:02:24.310000000
  
        encoder         : Lavc58.18.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/4000000 buffer size: 0 vbv_delay: -1
  
      Stream #0:1(eng): Audio: aac (LC), 44100 Hz, stereo, fltp, 512 kb/s (default)
  
      Metadata:
  
        LANGUAGE        : eng
  
        DURATION        : 00:02:24.348000000
  
        encoder         : Lavc58.18.100 aac
  
      Stream #0:2(und): Video: h264 (libx264), yuv420p(progressive), 960x540 [SAR 1:1 DAR 16:9], q=-1--1, 2500 kb/s, 30 fps, 90k tbn, 30 tbc (default)
  
      Metadata:
  
        CREATION_TIME   : 2017-01-27 05:02:53
  
        LANGUAGE        : und
  
        HANDLER_NAME    : VideoHandler
  
        DURATION        : 00:02:24.310000000
  
        encoder         : Lavc58.18.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/2500000 buffer size: 0 vbv_delay: -1
  
      Stream #0:3(eng): Audio: aac (LC), 44100 Hz, stereo, fltp, 256 kb/s (default)
  
      Metadata:
  
        LANGUAGE        : eng
  
        DURATION        : 00:02:24.348000000
  
        encoder         : Lavc58.18.100 aac
  
      Stream #0:4(und): Video: h264 (libx264), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 800 kb/s, 29 fps, 90k tbn, 29 tbc (default)
  
      Metadata:
  
        CREATION_TIME   : 2017-01-27 05:02:53
  
        LANGUAGE        : und
  
        HANDLER_NAME    : VideoHandler
  
        DURATION        : 00:02:24.310000000
  
        encoder         : Lavc58.18.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/800000 buffer size: 0 vbv_delay: -1
  
      Stream #0:5(eng): Audio: aac (LC), 44100 Hz, stereo, fltp, 255 kb/s (default)
  
      Metadata:
  
        LANGUAGE        : eng
  
        DURATION        : 00:02:24.348000000
  
        encoder         : Lavc58.18.100 aac
  
  [hls @ 0x6650000] Opening '/tmp/hls/gw_0.m3u8.tmp' for writing6.50 bitrate=N/A dup=12 drop=0 speed=0.965x    
  
  [hls @ 0x6650000] Opening '/tmp/hls/gw_1.m3u8.tmp' for writing
  
  [hls @ 0x6650000] Opening '/tmp/hls/gw_2.m3u8.tmp' for writing
  
  [hls @ 0x6650000] Opening '/tmp/hls/gw.m3u8' for writing

• Transcode any video to mp4 with max. 800 width or max. 800 height + watermark

  27 décembre 2018, par Mike

  I need a ffmpeg command that works with every video (with audio) format / type to encode it to h264 mp4. The output may have a maximum width of 800px and a maximum height of 800px. It would also be necesary to add a watermark in to bottom right corner... Is there a way to get all those things done with a single command line ? Even if it’s WMV, MOV, 3gp and whatever filetype is beeing used ?