mirror of
https://github.com/curioustorvald/tsvm.git
synced 2026-03-07 19:51:51 +09:00
262 lines
7.7 KiB
JavaScript
262 lines
7.7 KiB
JavaScript
/*
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TSVM Interchangeable Picture Format
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Image is divided into 4x4 blocks and each block is serialised, then the entire file is gzipped
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# File Structure
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\x1F T S V M i P F
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[HEADER]
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[Blocks.gz]
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- Header
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uint16 WIDTH
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uint16 HEIGHT
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uint16 HAS ALPHA
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uint8 3 (IPF CONFIG INDICATOR)
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byte[9] RESERVED
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- *.gz
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uint32 UNCOMPRESSED SIZE
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* PAYLOAD
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- Blocks
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4x4 pixels are sampled, then divided into YCoCg planes.
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CoCg planes are "chroma subsampled" by 4:2:0, then quantised to 4 bits (8 bits for CoCg combined)
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Y plane is quantised to 4 bits
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By doing so, CoCg planes will reduce to 4 pixels
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For the description of packing, pixels in Y plane will be numbered as:
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0 1 2 3
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4 5 6 7
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8 9 A B
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C D E F
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Bits are packed like so:
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uint32 SUBSAMPLING MASK (unimplemented; dont write this)
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uint8 [Co-2 | Co-1]
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uint8 [Co-4 | Co-3]
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uint8 [Co-6 | Co-5]
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uint8 [Co-8 | Co-7]
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uint8 [Cg-2 | Cg-1]
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uint8 [Cg-4 | Cg-3]
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uint8 [Cg-6 | Cg-5]
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uint8 [Cg-8 | Cg-7]
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uint16 [Y1 | Y0 | Y5 | Y4]
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uint16 [Y3 | Y2 | Y7 | Y6]
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uint16 [Y9 | Y8 | YD | YC]
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uint16 [YB | YA | YF | YE]
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(total: 16 bytes)
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If has alpha, append following bytes for alpha values
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uint16 [a1 | a0 | a5 | a4]
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uint16 [a3 | a2 | a7 | a6]
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uint16 [a9 | a8 | aD | aC]
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uint16 [aB | aA | aF | aE]
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(total: 24 bytes)
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Subsampling mask:
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Least significant byte for top-left, most significant for bottom-right
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For example, this default pattern
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00 00 01 01
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00 00 01 01
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10 10 11 11
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10 10 11 11
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turns into:
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01010000 -> 0x30
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01010000 -> 0x30
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11111010 -> 0xFA
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11111010 -> 0xFA
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which packs into: [ 30 | 30 | FA | FA ] (because little endian)
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- IPF CONFIG INDICATOR:
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0 for 4:2:0 Chroma subsampling for both Co and Cg (iPF Type 1)
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1 for 4:2:2 Chroma subsampling for Co, but 4:2:0 for Cg (NOT recommended; unused)
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2 for 4:2:2 Chroma subsampling for Cg, but 4:2:0 for Co (Recommended over type 1; unused)
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3 for 4:2:2 Chroma subsampling for both Co and Cg (iPF Type 2)
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*/
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if (!exec_args[2]) {
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printerrln("Usage: encodeipf input.jpg output.ipf [/noalpha]")
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return 1
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}
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let configUseAlpha = !(exec_args[3] != undefined && exec_args[3].toLowerCase() == "/noalpha")
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let pattern = 0
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filesystem.open("A", exec_args[1], "R")
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let status = com.getStatusCode(0)
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let infile = undefined
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if (0 != status) return status
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// read file
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let fileLen = filesystem.getFileLen("A")
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infile = sys.malloc(fileLen)
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dma.comToRam(0, 0, infile, fileLen)
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// decode
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const [imgw, imgh, imageData, channels] = graphics.decodeImage(infile, fileLen) // stored as [R | G | B | (A)]
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sys.free(infile)
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let hasAlpha = (4 == channels) && configUseAlpha
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let outBlock = sys.malloc(64)
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let blockSize = Math.ceil(imgh / 4.0) * Math.ceil(imgw / 4.0)
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let blockWidth = Math.ceil(imgw / 4.0)
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println(`Dim: ${imgw}x${imgh}, channels: ${channels}, Has alpha: ${hasAlpha}`)
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// TODO write output to dedicated ptr and gzip it
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let writeCount = 0
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let writeBuf = sys.malloc(blockSize * ((hasAlpha) ? 24 : 16))
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let bayerKernels = [
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[
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0,8,2,10,
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12,4,14,6,
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3,11,1,9,
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15,7,13,5,
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],
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[
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8,2,10,0,
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4,14,6,12,
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11,1,9,3,
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7,13,5,15,
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],
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[
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7,13,5,15,
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8,2,10,0,
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4,14,6,12,
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11,1,9,3,
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],
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[
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15,7,13,5,
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0,8,2,10,
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12,4,14,6,
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3,11,1,9,
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]
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].map(it => it.map(it => (it + 0.5) / 16))
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function chromaToFourBits(f) {
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let r = Math.round(f * 8) + 7
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return (r < 0) ? 0 : (r > 15) ? 15 : r
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}
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for (let blockY = 0; blockY < Math.ceil(imgh / 4.0); blockY++) {
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for (let blockX = 0; blockX < Math.ceil(imgw / 4.0); blockX++) {
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// println(`Encoding block ${1 + blockY * blockWidth + blockX}/${blockSize}`) // print statement is making things slower...
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let ys = new Uint8Array(16)
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let as = new Uint8Array(16)
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let cos = new Float32Array(16)
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let cgs = new Float32Array(16)
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for (let py = 0; py < 4; py++) { for (let px = 0; px < 4; px++) {
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// TODO oob-check
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let ox = blockX * 4 + px
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let oy = blockY * 4 + py
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let t = bayerKernels[pattern % bayerKernels.length][4 * (py % 4) + (px % 4)]
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let offset = channels * (oy * imgw + ox)
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let r0 = sys.peek(imageData + offset) / 255.0
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let g0 = sys.peek(imageData + offset+1) / 255.0
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let b0 = sys.peek(imageData + offset+2) / 255.0
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let a0 = (hasAlpha) ? sys.peek(imageData + offset+3) / 255.0 : 1.0
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let r = Math.floor((t / 15 + r0) * 15) / 15
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let g = Math.floor((t / 15 + g0) * 15) / 15
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let b = Math.floor((t / 15 + b0) * 15) / 15
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let a = Math.floor((t / 15 + a0) * 15) / 15
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let co = r - b // [-1..1]
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let tmp = b + co / 2.0
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let cg = g - tmp // [-1..1]
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let y = tmp + cg / 2.0 // [0..1]
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let index = py * 4 + px
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ys[index] = Math.round(y * 15)
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as[index] = Math.round(a * 15)
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cos[index] = co
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cgs[index] = cg
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}}
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// subsample by averaging
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let cos1 = chromaToFourBits((cos[0]+cos[1]) / 2.0)
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let cos2 = chromaToFourBits((cos[2]+cos[3]) / 2.0)
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let cos3 = chromaToFourBits((cos[4]+cos[5]) / 2.0)
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let cos4 = chromaToFourBits((cos[6]+cos[7]) / 2.0)
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let cos5 = chromaToFourBits((cos[8]+cos[9]) / 2.0)
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let cos6 = chromaToFourBits((cos[10]+cos[11]) / 2.0)
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let cos7 = chromaToFourBits((cos[12]+cos[13]) / 2.0)
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let cos8 = chromaToFourBits((cos[14]+cos[15]) / 2.0)
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let cgs1 = chromaToFourBits((cgs[0]+cgs[1]) / 2.0)
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let cgs2 = chromaToFourBits((cgs[2]+cgs[3]) / 2.0)
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let cgs3 = chromaToFourBits((cgs[4]+cgs[5]) / 2.0)
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let cgs4 = chromaToFourBits((cgs[6]+cgs[7]) / 2.0)
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let cgs5 = chromaToFourBits((cgs[8]+cgs[9]) / 2.0)
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let cgs6 = chromaToFourBits((cgs[10]+cgs[11]) / 2.0)
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let cgs7 = chromaToFourBits((cgs[12]+cgs[13]) / 2.0)
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let cgs8 = chromaToFourBits((cgs[14]+cgs[15]) / 2.0)
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// append encoded blocks to the file
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let outBlock = writeBuf + writeCount
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sys.poke(outBlock+ 0, (cos2 << 4) | cos1)
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sys.poke(outBlock+ 1, (cos4 << 4) | cos3)
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sys.poke(outBlock+ 2, (cos6 << 4) | cos5)
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sys.poke(outBlock+ 3, (cos8 << 4) | cos7)
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sys.poke(outBlock+ 4, (cgs2 << 4) | cgs1)
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sys.poke(outBlock+ 5, (cgs4 << 4) | cgs3)
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sys.poke(outBlock+ 6, (cgs6 << 4) | cgs5)
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sys.poke(outBlock+ 7, (cgs8 << 4) | cgs7)
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sys.poke(outBlock+ 8, (ys[1] << 4) | ys[0])
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sys.poke(outBlock+ 9, (ys[5] << 4) | ys[4])
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sys.poke(outBlock+10, (ys[3] << 4) | ys[2])
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sys.poke(outBlock+11, (ys[7] << 4) | ys[6])
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sys.poke(outBlock+12, (ys[9] << 4) | ys[8])
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sys.poke(outBlock+13, (ys[13] << 4) | ys[12])
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sys.poke(outBlock+14, (ys[11] << 4) | ys[10])
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sys.poke(outBlock+15, (ys[15] << 4) | ys[14])
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if (hasAlpha) {
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sys.poke(outBlock+16, (as[1] << 4) | as[0])
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sys.poke(outBlock+17, (as[5] << 4) | as[4])
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sys.poke(outBlock+18, (as[3] << 4) | as[2])
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sys.poke(outBlock+19, (as[7] << 4) | as[6])
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sys.poke(outBlock+20, (as[9] << 4) | as[8])
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sys.poke(outBlock+21, (as[13] << 4) | as[12])
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sys.poke(outBlock+22, (as[11] << 4) | as[10])
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sys.poke(outBlock+23, (as[15] << 4) | as[14])
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writeCount += 8
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}
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writeCount += 16
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}}
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// write header to the output file
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let headerBytes = [
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0x1F, 0x54, 0x53, 0x56, 0x4D, 0x69, 0x50, 0x46, // magic
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imgw & 255, (imgw >>> 8) & 255, // width
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imgh & 255, (imgh >>> 8) & 255, // height
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((hasAlpha) ? 1 : 0), 0x00, // has alpha
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0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 // reserved
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]
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filesystem.open("A", exec_args[2], "W")
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filesystem.writeBytes("A", headerBytes)
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filesystem.open("A", exec_args[2], "A")
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dma.ramToCom(writeBuf, 0, writeCount)
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sys.free(outBlock)
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sys.free(imageData)
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sys.free(writeBuf) |