Yearly Archives: 2006

AAC Puzzles

You thought those Pickover puzzles were inane? Well, you were right. But it does help to keep a programmer sharp on pure computer science skills. One reason I have been having such a good time reverse engineering the FAAD2 source is because it represents a bunch of little puzzles. Only they’re considerably more straightforward and grounded in reality than the Pickover puzzles. If these puzzles were on a Pickover calendar page, they would be worded along the lines of,

“There are 8,192 numbers stored in a table called iq_table. 0, 1, 2.5198420997897464, 4.3267487109222245, all the way up to 165113.4940829452. What is the common property that connects all of these numbers?”

The answer (thanks to Jindrich Makovicka for pointing this out on the ffmpeg-devel list) is that each number is its index (0..8191) raised to an exponent of 4/3: iq_table[index] = index4/3. Here are some more puzzles:

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Beaten By A Puzzle

It pains me to admit that I couldn’t even produce a computer program capable of solving a Pickover puzzle (update: But Aurel Jacobs could; read on). This is another graph traversal puzzle. The setup is that you have an 8×9 graph with 8 blocked nodes:

* * * * * * * *
* X * * * * * *
* * * X * X * *
* * * * * * * *
* * X * * * * *
* * * * * * * *
* X * * * * * *
* * * X * * * *
* * X X * * * *

Find a path that begins and ends on the same node that covers every unblocked square without crossing itself and moving only vertically or horizontally.

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First HD-DVD Hardware

This slipped by me for the first 2 months: Toshiba plans to release the first HD-DVD-capable hardware in the form of a laptop– the Qosmio laptop to be precise. Somewhere along the line the committee even came up with the following inspired logo:


HD-DVD ROM logo

The laptop sounds quite impressive, though. It can display a resolution 1440×900 on its 17″ screen. More interesting, though, is that the laptop functions as a portable entertainment center and is ready to be hooked up to an entertainment center with an HDTV and 5.1 channel sound. No price tag is listed yet. Who wants to be the first to bite, sparing no cost?

Then the tasks:

  1. get Linux installed on the laptop– how is Linux support on Toshiba laptops? I understand that Qosmio is a line of Toshiba laptops so there is probably some history of support or lack thereof
  2. get a commercial HD-DVD movie
  3. make sure Linux can access the raw sectors of the HD-DVD (via ATAPI?), maybe even mount the filesystems (ISO-9660? UDF?)
  4. figure out the AACS encryption scheme using the Windows player; find where the key lives and how to use it to get the plaintext content
  5. figure out all the weird and wonderful video codecs, audio codecs, subtitle formats, and navigation technologies employed on the disc
  6. … ??? …
  7. profit!, or achieve international notoriety

It feels good to have a plan, I know.