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• Compilation of x264 with newest libswscale and libavformat

  4 décembre 2016, par pcroland

  Yesterday I wanted to compile x264 myself because the latest binary on videolan is compiled without libswscale : link

  If I just use

  ./configure --enable-static --enable-shared

  then the binary will compile libswscale 3.1.101 and libavformat 56.40.101 from the libswscale-dev and libavformat-dev packages. If I clone FFmpeg’s git and use

  ./configure --enable-static --enable-shared --extra-cflags="-I$HOME/FFmpeg"

  the binary will have the latest libswscale and libavformat, but it wont work :

  pc@pcroland:~/bin$ ./x264 --version
  
  x264 0.148.2744 b97ae06
  
  (libswscale 4.3.101)
  
  (libavformat 57.58.101)
  
  built on Dec  4 2016, gcc: 5.4.0 20160609
  
  x264 configuration: --bit-depth=8 --chroma-format=all
  
  libx264 configuration: --bit-depth=8 --chroma-format=all
  
  x264 license: GPL version 2 or later
  
  libswscale/libavformat license: GPL version 2 or later
  
  pc@pcroland:~/bin$ ./x264 --input-res 1920x1080 --fps 24000/1001 --vf resize:720,404,method=spline --output /home/pc/test.264 /home/pc/asd.264
  
  [h264 @ 0x1bc3ec0] Format h264 detected only with low score of 1, misdetection possible!
  
  [h264 @ 0x1bc3ec0] Could not find codec parameters for stream 0 (Video: h264, none): unspecified size
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  lavf [error]: could not find input stream info
  
  avs [error]: failed to load avisynth
  
  raw [info]: 1920x1080p 0:0 @ 24000/1001 fps (cfr)
  
  resize [info]: resizing to 720x404
  
  x264 [info]: using SAR=404/405
  
  x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
  
  x264 [info]: profile High, level 3.0
  
  Bus error (core dumped)
  
  pc@pcroland:~/bin$

  How to reproduce the error :

  cd; git clone https://github.com/FFmpeg/FFmpeg; git clone http://git.videolan.org/git/x264.git; cd x264; ./configure --enable-static --enable-shared --extra-cflags="-I$HOME/FFmpeg" --bindir="$HOME/bin"; sudo make; sudo make install

  System : Ubuntu 16.04

• Troll spirit

  15 juin 2013, par Mans — Law and liberty

  Last week’s announcements from the White House of steps being taken to begin fighting back against patent trolls, along with legislation passed in Vermont for the same purpose, are worthy of praise. Whether they prove effective or not, they are a sign of the problem finally having been recognised by the highest authorities. That said, only one aspect of the issue is addressed, that of non-practising entities or trolls. Little effort is being made to stymie troll-like behaviour from otherwise legitimate actors. While a stake is driven through the heart of the troll, its spirit remains free to roam the corporate world, and like a demon of darkness it possesses companies, compelling them to engage in the very practices we seek to eradicate.

  The demon

  The most damaging, when wielded by a troll, are those patents with vague or overly broad claims. These can easily be asserted against large numbers of alleged infringers, many of which likely choose to settle out of court rather than risk an expensive litigation process with uncertain outcome. Such negotiations are frequently subject to non-disclosure agreements prohibiting publication of details in any deals, or even the existence thereof. As a result, an accused has no way of assessing a fair price for a licence (assuming the patent is in fact valid), and the patent holder can thus extract from each would-be infringer precisely as much as they are willing or able to pay to avoid a lawsuit.

  At the root of this problem is the ease with which applications for the patents in question are granted. Given the volume of patent applications, it is hardly reasonable to demand a hugely more extensive examination process than currently takes place (although some improvements here are no doubt possible) ; after all, a speedy decision is in the best interest of all parties. The solution must evidently be found elsewhere.

  The exorcism

  An obvious cure to the problem is the abolishment of the patent system. As this is clearly not feasible today, more practical, albeit less effective, remedies must be sought. A few ideas follow.

  Make patent validity all or nothing

  Change the rules such that any claim being found invalid cancels the patent its entirety. With the full patent at stake in this manner, companies would be discouraged from gambling on frivolous claims and encouraged to conduct a more thorough background investigation before filing.

  Maintain a registry of licences

  Require that all patent licence agreements be filed in an open, easily searchable registry. This would hopefully increase fairness in licensing deals.

  Mandate reimbursement of licence fees for invalidated patents

  If a patent is challenged and found invalid, require that the owner reimburse any licence fees previously collected for the patent in question. Apart from being morally right, this could act as a deterrent to over-charging. The amount requested for a licence would likely be balanced against the risk of being made to pay it all back later, resulting in lower licence fees for low-confidence patents.

  These suggestions, alone or together, will not completely eradicate the problems of patent abuse. They are but small steps towards a more thorough overhaul of a system increasingly ill-suited to the nature and pace of modern technological development.

• Translating Return To Ringworld

  17 août 2016, par Multimedia Mike — Game Hacking

  As indicated in my previous post, the Translator has expressed interest in applying his hobby towards another DOS adventure game from the mid 1990s : Return to Ringworld (henceforth R2RW) by Tsunami Media. This represents significantly more work than the previous outing, Phantasmagoria.

  
  
  Return to Ringworld Title Screen
  

  I have been largely successful thus far in crafting translation tools. I have pushed the fruits of these labors to a Github repository named improved-spoon (named using Github’s random name generator because I wanted something more interesting than ‘game-hacking-tools’).

  Further, I have recorded everything I have learned about the game’s resource format (named RLB) at the XentaxWiki.

  New Challenges
  The previous project mostly involved scribbling subtitle text on an endless series of video files by leveraging a separate software library which took care of rendering fonts. In contrast, R2RW has at least 30k words of English text contained in various blocks which require translation. Further, the game encodes its own fonts (9 of them) which stubbornly refuse to be useful for rendering text in nearly any other language.

  Thus, the immediate 2 challenges are :
  

  1. Translating volumes of text to Spanish
  2. Expanding the fonts to represent Spanish characters

  Normally, “figuring out the file format data structures involved” is on the list as well. Thankfully, understanding the formats is not a huge challenge since the folks at the ScummVM project already did all the heavy lifting of reverse engineering the file formats.

  The Pitch
  Here was the plan :

  • Create a tool that can dump out the interesting data from the game’s master resource file.
  • Create a tool that can perform the elaborate file copy described in the previous post. The new file should be bit for bit compatible with the original file.
  • Modify the rewriting tool to repack some modified strings into the new resource file.
  • Unpack the fonts and figure out a way to add new characters.
  • Repack the new fonts into the resource file.
  • Repack message strings with Spanish characters.

  Showing The Work : Modifying Strings
  First, I created the tool to unpack blocks of message string resources. I elected to dump the strings to disk as JSON data since it’s easy to write and read JSON using Python, and it’s quick to check if any mistakes have crept in.

  The next step is to find a string to focus on. So I started the game and looked for the first string I could trigger :

  
  
  

  This shows up in the JSON string dump as :

    
      "Spanish" : " !0205Your quarters on the Lance of Truth are spartan, in accord with your mercenary lifestyle.",
      "English" : " !0205Your quarters on the Lance of Truth are spartan, in accord with your mercenary lifestyle."
    ,
  

  As you can see, many of the strings are encoded with an ID key as part of the string which should probably be left unmodified. I changed the Spanish string :

    
      "Spanish" : " !0205Hey, is this thing on ?",
      "English" : " !0205Your quarters on the Lance of Truth are spartan, in accord with your mercenary lifestyle."
    ,
  

  And then I wrote the repacking tool to substitute this message block for the original one. Look ! The engine liked it !

  
  
  

  Little steps, little steps.

  Showing The Work : Modifying Fonts
  The next little step is to find a place to put the new characters. First, a problem definition : The immediate goal is to translate the game into Spanish. The current fonts encoded in the game resource only support 128 characters, corresponding to 7-bit ASCII. In order to properly express Spanish, 16 new characters are required : á, é, í, ó, ú, ü, ñ (each in upper and lower case for a total of 14 characters) as well as the inverted punctuation symbols : ¿, ¡.

  Again, ScummVM already documents (via code) the font coding format. So I quickly determined that each of the 9 fonts is comprised of 128 individual bitmaps with either 1 or 2 bits per pixel. I wrote a tool to unpack each character into an individual portable grey map (PGM) image. These can be edited with graphics editors or with text editors since they are just text files.

  Where to put the 16 new Spanish characters ? ASCII characters 1-31 are non-printable, so my first theory was that these characters would be empty and could be repurposed. However, after dumping and inspecting, I learned that they represent the same set of characters as seen in DOS Code Page 437. So that’s a no-go (so I assumed ; I didn’t check if any existing strings leveraged those characters).

  My next plan was hope that I could extend the font beyond index 127 and use positions 128-143. This worked superbly. This is the new example string :

    
      "Spanish" : " !0205¿Ves esto ? ¡La puntuacion se hace girar !",
      "English" : " !0205Your quarters on the Lance of Truth are spartan, in accord with your mercenary lifestyle."
    ,
  

  Fortunately, JSON understands UTF-8 and after mapping the 16 necessary characters down to the numeric range of 128-143, I repacked the new fonts and the new string :

  
  
  Translation : “See this ? The punctuation is rotated !”
  

  Another victory. Notice that there are no diacritics in this string. None are required for this translation (according to Google Translate). But adding the diacritics to the 14 characters isn’t my department. My tool does help by prepopulating [aeiounAEIOUN] into the right positions to make editing easier for the Translator. But the tool does make the effort to rotate the punctuation since that is easy to automate.

  Next Steps and Residual Weirdness
  There is another method for storing ASCII text inside the R2RW resource called strip resources. These store conversation scripts. There are plenty of fields in the data structures that I don’t fully understand. So, following the lessons I learned from my previous translation outing, I was determined to modify as little as possible. This means copying over most of the original data structures intact, but changing the field representing the relative offset that points to the corresponding string. This works well since the strings are invariably stored NULL-terminated in a concatenated manner.

  I wanted to document for the record that the format that R2RW uses has some weirdness in they way it handles residual bytes in a resource. The variant of the resource format that R2RW uses requires every block to be aligned on a 16-byte boundary. If there is space between the logical end of the resource and the start of the next resource, there are random bytes in that space. This leads me to believe that these bytes were originally recorded from stale/uninitialized memory. This frustrates me because when I write the initial file copy tool which unpacks and repacks each block, I want the new file to be identical to the original. However, these apparent nonsense bytes at the end thwart that effort.

  But leaving those bytes as 0 produces an acceptable resource file.

  Text On Static Images
  There is one last resource type we are working on translating. There are various bits of text that are rendered as images. For example, from the intro :

  
  
  

  It’s possible to locate and extract the exact image that is overlaid on this scene, though without the colors :

  
  
  

  The palettes are stored in a separate resource type. So it seems the challenge is to figure out the palette in use for these frames and render a transparent image that uses the same palette, then repack the new text-image into the new resource file.

  The post Translating Return To Ringworld first appeared on Breaking Eggs And Making Omelettes.