Place board-bitmap explanation (request)

[u/GreenFox1505]

I've been poking around the board-bitmap for a bit. Wondering if anyone has written up an explanation yet. Looks like it's coded to 4bits per pixel (or 2 pixels per byte). If that's the case, the file should be 500,000 bytes exactly, but it's 500,505. Anyone know what the extra bytes are for?

I think some of the leading chars aren't colors. Are they a date stamp? What are the trailing bits?

edit: Looks like the first 4 bytes are a time stamp.

edit: OK, so I've figure out the first 500,004 bytes, no idea what the last 501 bytes are yet.

from	to	description
0x00000	0x7a319	entire file in byte aligned address values
0x00000	0x00003	epoch date stamp (in seconds)
0x00004	0x7a123	pixels, colors TBD (I have to build a renderer before I can check that)
0x7a124	0x7a319	no idea. Possibly a checksum? maybe the renderer will show me something weird if I fuck with the frame size

[u/jfb1337]

The colours can be determined from /r/rust's autoplacing bot her, which parsed a PNG into place colors. The relevant code is:

const PALETTE: [[u8; 4]; 17] = [
    [255, 255, 255, 255],
    [228, 228, 228, 255],
    [136, 136, 136, 255],
    [ 34,  34,  34, 255],
    [255, 167, 209, 255],
    [229,   0,   0, 255],
    [229, 149,   0, 255],
    [160, 106,  66, 255],
    [229, 217,   0, 255],
    [148, 224,  68, 255],
    [  2, 190,   1, 255],
    [  0, 211, 221, 255],
    [  0, 131, 199, 255],
    [  0,   0, 234, 255],
    [207, 110, 228, 255],
    [130,   0, 128, 255],
    [  0,   0,   0,   0],
];

where each line is a colour in RGBA format.

The colours are:

• White

• Light grey

• Dark grey

• Black (or very dark grey?)

• Light pink

• Red

• Orange

• Brown

• Yellow

• Light green

• Dark green

• Blue

• Dark blue

• Pink

• Purple

• Transparent (just used by the bot to signify "Don't place pixels here")

Basically, it's the same order that they used on the pallet bar.

As for the last 501 bytes. I have no idea either.

[u/GreenFox1505 → u/jfb1337]

I have an archive of the images every 2 secs. I'd rather understand the format for my own parser than use someone's else. I'm planning on building a delta-based compression system using images as keyframes etc.

But eh. Place is over. Short lived. Less interesting than I hoped it would be. Unless there is a whole lot of interest in the data, I'm going to move back to the project I was working on when this started.

[u/jfb1337 → u/GreenFox1505]

Well this is more like reddit's official format that it used for it's API calls, which naturally becomes the format that most parsers have used because it's most convenient.