msla deltas and file format normalization
This commit is contained in:
Stewart Allen
parent
1cc56311f7
commit
50e0a4674b
2 changed files with 1316 additions and 1243 deletions
|
|
@ -1,429 +1,430 @@
|
|||
# mSLA Format Reference - Critical Addendum
|
||||
## CTB RLE & PM4N Version Corrections
|
||||
|
||||
**Date:** 2026-05-16
|
||||
**Status:** Code-verified corrections to v2 reference
|
||||
|
||||
---
|
||||
|
||||
## Issue 1: CTB RLE Encoding - CORRECTED
|
||||
|
||||
### Previous (Incorrect) Description
|
||||
"RLE125: Simple 2-byte fixed format (color, length), max 125 pixels"
|
||||
|
||||
### Actual Implementation (from ChituboxFile.cs:825-908)
|
||||
|
||||
CTB uses a **7-bit grayscale variable-length RLE** with optional encryption, NOT simple RLE125.
|
||||
|
||||
#### Encoding Algorithm
|
||||
|
||||
**Step 1: Color Quantization**
|
||||
```c
|
||||
grey7 = pixel_value >> 1 // Convert 8-bit (0-255) to 7-bit (0-127)
|
||||
```
|
||||
|
||||
**Step 2: Variable-Length Run Encoding**
|
||||
|
||||
The encoding uses a **variable-length stride format**:
|
||||
|
||||
| Stride Length | Bytes | Format | Description |
|
||||
|--------------|-------|--------|-------------|
|
||||
| 1 pixel | 1 byte | `[0ccccccc]` | Color only, bit 7 clear |
|
||||
| 2-127 pixels | 2 bytes | `[1ccccccc] [0rrrrrrr]` | Color + 7-bit length |
|
||||
| 128-16383 pixels | 3 bytes | `[1ccccccc] [10rrrrrr] [rrrrrrrr]` | Color + 14-bit length |
|
||||
| 16384-2097151 pixels | 4 bytes | `[1ccccccc] [110rrrrr] [rrrrrrrr] [rrrrrrrr]` | Color + 21-bit length |
|
||||
| 2097152-268435455 pixels | 5 bytes | `[1ccccccc] [1110rrrr] [rrrrrrrr] [rrrrrrrr] [rrrrrrrr]` | Color + 28-bit length |
|
||||
|
||||
**Bit Layout:**
|
||||
- `c` = color bits (7-bit grayscale, 0-127)
|
||||
- `r` = repeat/stride bits
|
||||
- Bit 7 of first byte: `1` if stride > 1, `0` if stride == 1
|
||||
- Length byte prefix bits indicate multi-byte length encoding
|
||||
|
||||
#### Detailed Encoding Logic (from source)
|
||||
|
||||
```c
|
||||
void AddRep()
|
||||
{
|
||||
if (stride == 0) return;
|
||||
|
||||
if (stride > 1) {
|
||||
color |= 0x80; // Set bit 7 to indicate run follows
|
||||
}
|
||||
rawData.Add(color);
|
||||
|
||||
if (stride <= 1) {
|
||||
// Single pixel: just the color byte
|
||||
return;
|
||||
}
|
||||
|
||||
if (stride <= 0x7f) { // 127
|
||||
// 1-byte length: [0rrrrrrr]
|
||||
rawData.Add((byte)stride);
|
||||
return;
|
||||
}
|
||||
|
||||
if (stride <= 0x3fff) { // 16383
|
||||
// 2-byte length: [10rrrrrr] [rrrrrrrr]
|
||||
rawData.Add((byte)((stride >> 8) | 0x80));
|
||||
rawData.Add((byte)stride);
|
||||
return;
|
||||
}
|
||||
|
||||
if (stride <= 0x1fffff) { // 2097151
|
||||
// 3-byte length: [110rrrrr] [rrrrrrrr] [rrrrrrrr]
|
||||
rawData.Add((byte)((stride >> 16) | 0xc0));
|
||||
rawData.Add((byte)(stride >> 8));
|
||||
rawData.Add((byte)stride);
|
||||
return;
|
||||
}
|
||||
|
||||
if (stride <= 0xfffffff) { // 268435455
|
||||
// 4-byte length: [1110rrrr] [rrrrrrrr] [rrrrrrrr] [rrrrrrrr]
|
||||
rawData.Add((byte)((stride >> 24) | 0xe0));
|
||||
rawData.Add((byte)(stride >> 16));
|
||||
rawData.Add((byte)(stride >> 8));
|
||||
rawData.Add((byte)stride);
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
#### Decoding Algorithm
|
||||
|
||||
```python
|
||||
def decode_ctb_rle(data: bytes, width: int, height: int) -> bytes:
|
||||
pixels = bytearray(width * height)
|
||||
pixel_pos = 0
|
||||
i = 0
|
||||
|
||||
while i < len(data):
|
||||
color_byte = data[i]
|
||||
i += 1
|
||||
|
||||
# Extract 7-bit color
|
||||
color = (color_byte & 0x7F) << 1 # Expand back to 8-bit
|
||||
|
||||
# Check if run follows (bit 7 set)
|
||||
if (color_byte & 0x80) == 0:
|
||||
# Single pixel
|
||||
pixels[pixel_pos] = color
|
||||
pixel_pos += 1
|
||||
continue
|
||||
|
||||
# Multi-pixel run: decode length
|
||||
length_byte = data[i]
|
||||
i += 1
|
||||
|
||||
if (length_byte & 0x80) == 0:
|
||||
# 1-byte length (7 bits)
|
||||
stride = length_byte
|
||||
elif (length_byte & 0x40) == 0:
|
||||
# 2-byte length (14 bits)
|
||||
stride = ((length_byte & 0x3F) << 8) | data[i]
|
||||
i += 1
|
||||
elif (length_byte & 0x20) == 0:
|
||||
# 3-byte length (21 bits)
|
||||
stride = ((length_byte & 0x1F) << 16) | (data[i] << 8) | data[i+1]
|
||||
i += 2
|
||||
else:
|
||||
# 4-byte length (28 bits)
|
||||
stride = ((length_byte & 0x0F) << 24) | (data[i] << 16) | (data[i+1] << 8) | data[i+2]
|
||||
i += 3
|
||||
|
||||
# Fill pixels
|
||||
for _ in range(stride):
|
||||
pixels[pixel_pos] = color
|
||||
pixel_pos += 1
|
||||
|
||||
return pixels
|
||||
```
|
||||
|
||||
#### Encryption (Optional)
|
||||
|
||||
If `HeaderSettings.EncryptionKey > 0`, RLE data is XORed with a per-layer key:
|
||||
|
||||
**Encryption Algorithm (from ChituboxFile.cs:2227-2248):**
|
||||
```c
|
||||
void LayerRleCryptBuffer(uint seed, uint layerIndex, byte[] input)
|
||||
{
|
||||
if (seed == 0) return;
|
||||
|
||||
uint init = seed * 0x2d83cdac + 0xd8a83423;
|
||||
uint key = (layerIndex * 0x1e1530cd + 0xec3d47cd) * init;
|
||||
|
||||
int index = 0;
|
||||
for (int i = 0; i < input.Length; i++)
|
||||
{
|
||||
byte k = (byte)(key >> (8 * index));
|
||||
index++;
|
||||
|
||||
if ((index & 3) == 0) {
|
||||
key += init;
|
||||
index = 0;
|
||||
}
|
||||
|
||||
input[i] = (byte)(input[i] ^ k);
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
**Key Generation:**
|
||||
```
|
||||
init = seed * 0x2D83CDAC + 0xD8A83423
|
||||
key_base = (layerIndex * 0x1E1530CD + 0xEC3D47CD) * init
|
||||
|
||||
For each 4-byte block:
|
||||
XOR with bytes from key_base (little-endian)
|
||||
After 4 bytes, update: key_base += init
|
||||
```
|
||||
|
||||
#### Anti-Aliasing Support
|
||||
|
||||
CTB format supports 7-bit grayscale (128 levels), enabling smooth anti-aliasing:
|
||||
- 0x00 = fully masked (black)
|
||||
- 0x7F = fully exposed (white)
|
||||
- 0x01-0x7E = partial exposure (anti-aliasing)
|
||||
|
||||
#### Example Encodings
|
||||
|
||||
**Example 1: Single white pixel**
|
||||
```
|
||||
Input: 1 pixel at value 255
|
||||
Encoded: 7F
|
||||
- grey7 = 255 >> 1 = 127 = 0x7F
|
||||
- stride = 1, so bit 7 stays clear
|
||||
- Output: [0x7F] (1 byte)
|
||||
```
|
||||
|
||||
**Example 2: Run of 100 white pixels**
|
||||
```
|
||||
Input: 100 pixels at value 255
|
||||
Encoded: FF 64
|
||||
- grey7 = 127 = 0x7F
|
||||
- stride = 100 = 0x64
|
||||
- 100 <= 127, so 1-byte length
|
||||
- color with bit 7 set: 0x7F | 0x80 = 0xFF
|
||||
- Output: [0xFF] [0x64] (2 bytes)
|
||||
```
|
||||
|
||||
**Example 3: Run of 500 gray pixels (value 128)**
|
||||
```
|
||||
Input: 500 pixels at value 128
|
||||
Encoded: C0 81 F4
|
||||
- grey7 = 128 >> 1 = 64 = 0x40
|
||||
- stride = 500 = 0x1F4
|
||||
- 500 > 127 and <= 16383, so 2-byte length
|
||||
- color with bit 7: 0x40 | 0x80 = 0xC0
|
||||
- length high: (500 >> 8) | 0x80 = 0x01 | 0x80 = 0x81
|
||||
- length low: 500 & 0xFF = 0xF4
|
||||
- Output: [0xC0] [0x81] [0xF4] (3 bytes)
|
||||
```
|
||||
|
||||
**Example 4: Run of 20000 pixels**
|
||||
```
|
||||
Input: 20000 pixels at value 200
|
||||
Encoded: E4 C4 E2 20
|
||||
- grey7 = 200 >> 1 = 100 = 0x64
|
||||
- stride = 20000 = 0x4E20
|
||||
- 20000 > 16383, so 3-byte length
|
||||
- color: 0x64 | 0x80 = 0xE4
|
||||
- length encoding: 0x4E20 with 0xC0 prefix
|
||||
- byte 0: (0x4E20 >> 16) | 0xC0 = 0x00 | 0xC0 = 0xC0
|
||||
- Wait, let me recalculate...
|
||||
- Actually 20000 = 0x4E20
|
||||
- High nibble: 0x4, middle: 0xE, low: 0x20
|
||||
- Prefix: ((0x4E20 >> 16) & 0x1F) | 0xC0 = 0x00 | 0xC0 = 0xC0
|
||||
- Byte 1: 0x4E20 >> 8 = 0x4E
|
||||
- Byte 2: 0x4E20 & 0xFF = 0x20
|
||||
- Output: [0xE4] [0xC0] [0x4E] [0x20] (4 bytes)
|
||||
```
|
||||
|
||||
#### Key Differences from Simple RLE125
|
||||
|
||||
| Feature | Simple RLE125 | CTB Variable RLE |
|
||||
|---------|---------------|------------------|
|
||||
| **Color depth** | 8-bit (0-255) | 7-bit (0-127) |
|
||||
| **Max run (1-byte)** | 125 | 127 |
|
||||
| **Max run (total)** | 125 | 268,435,455 |
|
||||
| **Bytes per run** | 2 (fixed) | 1-5 (variable) |
|
||||
| **Single pixel** | 2 bytes | 1 byte |
|
||||
| **Anti-aliasing** | Binary or limited | Full 7-bit grayscale |
|
||||
| **Encryption** | No | Optional per-layer XOR |
|
||||
| **Compression** | Moderate | Better for long runs |
|
||||
|
||||
#### Implementation Recommendations
|
||||
|
||||
1. **Decoding CTB:**
|
||||
- Read color byte
|
||||
- Check bit 7 for run flag
|
||||
- If clear: single pixel
|
||||
- If set: decode variable-length stride
|
||||
- Apply encryption if seed != 0
|
||||
|
||||
2. **Encoding CTB:**
|
||||
- Quantize to 7-bit: `grey7 = pixel >> 1`
|
||||
- Group consecutive identical pixels
|
||||
- Encode with optimal byte count (1-5 bytes)
|
||||
- Apply encryption if required
|
||||
|
||||
3. **Encryption Handling:**
|
||||
- Always check `HeaderSettings.EncryptionKey`
|
||||
- If non-zero, decrypt before RLE decode
|
||||
- Use layer-specific key derivation
|
||||
|
||||
---
|
||||
|
||||
## Issue 2: .pm4n Version Classification - AMBIGUOUS
|
||||
|
||||
### Current Status in UVtools
|
||||
|
||||
**Extension Registration:**
|
||||
```c
|
||||
// AnycubicFile.cs:1058
|
||||
new(typeof(AnycubicFile), "pm4n", "Photon Mono 4 (PM4N)")
|
||||
```
|
||||
|
||||
**Machine Mapping:**
|
||||
```c
|
||||
// AnycubicFile.cs:1731-1733
|
||||
if (FileEndsWith(".pm4n"))
|
||||
{
|
||||
return AnyCubicMachine.PhotonMono4;
|
||||
}
|
||||
```
|
||||
|
||||
**Version Mapping:**
|
||||
```c
|
||||
// AnycubicFile.cs:1155-1191
|
||||
public override uint[] GetAvailableVersionsForExtension(string? extension)
|
||||
{
|
||||
switch (extension)
|
||||
{
|
||||
case "pm3n":
|
||||
case "pm5":
|
||||
case "px6s":
|
||||
return [VERSION_517]; // ← pm3n, pm5, px6s are v517
|
||||
|
||||
case "pm5s":
|
||||
case "m5sp":
|
||||
return [VERSION_518]; // ← pm5s, m5sp are v518
|
||||
|
||||
// NOTE: .pm4n is NOT in the switch statement!
|
||||
|
||||
default:
|
||||
return AvailableVersions; // ← .pm4n falls through here
|
||||
}
|
||||
}
|
||||
|
||||
// AvailableVersions = [VERSION_1, VERSION_515, VERSION_516, VERSION_517, VERSION_518]
|
||||
```
|
||||
|
||||
### The Ambiguity
|
||||
|
||||
**`.pm4n` extension:**
|
||||
- ✓ Registered as valid extension
|
||||
- ✓ Maps to PhotonMono4 machine
|
||||
- ✗ **NOT** explicitly assigned to any version in `GetAvailableVersionsForExtension`
|
||||
- Returns all versions: `[1, 515, 516, 517, 518]`
|
||||
|
||||
### Possible Interpretations
|
||||
|
||||
1. **Oversight:** UVtools forgot to add .pm4n to the v517 case block
|
||||
2. **Intentional:** .pm4n can legitimately be multiple versions (firmware evolution)
|
||||
3. **Unknown:** Insufficient real-world fixtures to determine correct version
|
||||
|
||||
### User Implementation Note
|
||||
|
||||
**User's current implementation treats `.pm4n` as v517**, which is:
|
||||
- ✓ Consistent with similar naming (.pm3n, .pm5 are v517)
|
||||
- ✓ Logical based on product generation
|
||||
- ⚠️ **UNVERIFIED** by UVtools code (could be any version)
|
||||
|
||||
### Recommendations
|
||||
|
||||
**For Implementation:**
|
||||
```c
|
||||
// Conservative approach (allow multiple versions):
|
||||
if (extension == "pm4n") {
|
||||
return [VERSION_515, VERSION_516, VERSION_517];
|
||||
}
|
||||
|
||||
// Aggressive approach (assume v517 based on naming):
|
||||
if (extension == "pm4n") {
|
||||
return [VERSION_517];
|
||||
}
|
||||
```
|
||||
|
||||
**For Validation:**
|
||||
1. Obtain real .pm4n fixture files from PhotonMono4 printer
|
||||
2. Decode header and check `FileMarkSettings.Version` value
|
||||
3. Verify layer table structure (92 bytes = v517, 96 bytes = v518)
|
||||
4. Document actual version found in fixtures
|
||||
|
||||
**Fixture Verification Checklist:**
|
||||
- [ ] Acquire .pm4n file from PhotonMono4
|
||||
- [ ] Read offset 0x02 (uint16 Version field)
|
||||
- [ ] Check layer table entry size
|
||||
- [ ] Verify preview count (2 = v515/516, 7 = v517, 9 = v518)
|
||||
- [ ] Document findings
|
||||
|
||||
### Comparison with Similar Extensions
|
||||
|
||||
| Extension | Machine | Version in Code | Logic |
|
||||
|-----------|---------|-----------------|-------|
|
||||
| .pm3n | PhotonMono2 | 517 (explicit) | ✓ Defined |
|
||||
| **.pm4n** | **PhotonMono4** | **??? (default all)** | ⚠️ **Ambiguous** |
|
||||
| .pm5 | PhotonMonoM5 | 517 (explicit) | ✓ Defined |
|
||||
| .pm5s | PhotonMonoM5s | 518 (explicit) | ✓ Defined |
|
||||
|
||||
**Pattern suggests:** .pm4n should likely be v517, but this is **NOT verified in UVtools source**.
|
||||
|
||||
---
|
||||
|
||||
## Updated Classification
|
||||
|
||||
### Anycubic Modern Formats (CORRECTED)
|
||||
|
||||
| Extension | Machine | Version | Status |
|
||||
|-----------|---------|---------|--------|
|
||||
| .pm3n | PhotonMono2 | 517 | ✓ Verified |
|
||||
| **.pm4n** | **PhotonMono4** | **517 (assumed)** | **⚠️ UNVERIFIED** |
|
||||
| .pm5 | PhotonMonoM5 | 517 | ✓ Verified |
|
||||
| .px6s | PhotonMonoX6Ks | 517 | ✓ Verified |
|
||||
| .pm5s | PhotonMonoM5s | 518 | ✓ Verified |
|
||||
| .m5sp | PhotonMonoM5sPro | 518 | ✓ Verified |
|
||||
|
||||
### Action Items for Documentation
|
||||
|
||||
1. **CTB RLE:** Update main reference with variable-length encoding details
|
||||
2. **.pm4n:** Mark as "Assumed v517, requires fixture validation"
|
||||
3. **Testing:** Add note about lack of test fixtures in UVtools repository
|
||||
4. **Encryption:** Document optional per-layer XOR encryption for CTB
|
||||
|
||||
---
|
||||
|
||||
## Code References
|
||||
|
||||
**CTB RLE Encoding:**
|
||||
- Implementation: `ChituboxFile.cs:825-908` (EncodeCtbImage)
|
||||
- Decoding: `ChituboxFile.cs:685-745` (DecodeImage)
|
||||
- Encryption: `ChituboxFile.cs:2220-2248` (LayerRleCrypt)
|
||||
|
||||
**Anycubic Versions:**
|
||||
- Extension mapping: `AnycubicFile.cs:1155-1191` (GetAvailableVersionsForExtension)
|
||||
- Machine detection: `AnycubicFile.cs:1731-1733` (FileEndsWith check)
|
||||
- Version constants: `AnycubicFile.cs:30-33` (VERSION_515-518)
|
||||
|
||||
---
|
||||
|
||||
## Summary
|
||||
|
||||
**CTB RLE:**
|
||||
- ❌ Previous: Simple RLE125 (2 bytes/run, max 125)
|
||||
- ✅ Correct: Variable-length 7-bit grayscale RLE (1-5 bytes/run, max 268M, optional encryption)
|
||||
|
||||
**.pm4n Version:**
|
||||
- ❌ Previous: Listed under v517 without caveat
|
||||
- ✅ Correct: Ambiguous in UVtools (defaults to all versions), **assumed v517 pending fixture validation**
|
||||
|
||||
**Document Status:** Ready for integration into main reference with caveats noted.
|
||||
# mSLA Format Reference - Critical Addendum
|
||||
## CTB RLE & PM4N Version Corrections
|
||||
|
||||
**Date:** 2026-05-16
|
||||
**Status:** Code-verified corrections to v2 reference
|
||||
|
||||
---
|
||||
|
||||
## Issue 1: CTB RLE Encoding - CORRECTED
|
||||
|
||||
### Previous (Incorrect) Description
|
||||
"RLE125: Simple 2-byte fixed format (color, length), max 125 pixels"
|
||||
|
||||
### Actual Implementation (from ChituboxFile.cs:825-908)
|
||||
|
||||
CTB uses a **7-bit grayscale variable-length RLE** with optional encryption, NOT simple RLE125.
|
||||
|
||||
#### Encoding Algorithm
|
||||
|
||||
**Step 1: Color Quantization**
|
||||
```c
|
||||
grey7 = pixel_value >> 1 // Convert 8-bit (0-255) to 7-bit (0-127)
|
||||
```
|
||||
|
||||
**Step 2: Variable-Length Run Encoding**
|
||||
|
||||
The encoding uses a **variable-length stride format**:
|
||||
|
||||
| Stride Length | Bytes | Format | Description |
|
||||
|--------------|-------|--------|-------------|
|
||||
| 1 pixel | 1 byte | `[0ccccccc]` | Color only, bit 7 clear |
|
||||
| 2-127 pixels | 2 bytes | `[1ccccccc] [0rrrrrrr]` | Color + 7-bit length |
|
||||
| 128-16383 pixels | 3 bytes | `[1ccccccc] [10rrrrrr] [rrrrrrrr]` | Color + 14-bit length |
|
||||
| 16384-2097151 pixels | 4 bytes | `[1ccccccc] [110rrrrr] [rrrrrrrr] [rrrrrrrr]` | Color + 21-bit length |
|
||||
| 2097152-268435455 pixels | 5 bytes | `[1ccccccc] [1110rrrr] [rrrrrrrr] [rrrrrrrr] [rrrrrrrr]` | Color + 28-bit length |
|
||||
|
||||
**Bit Layout:**
|
||||
- `c` = color bits (7-bit grayscale, 0-127)
|
||||
- `r` = repeat/stride bits
|
||||
- Bit 7 of first byte: `1` if stride > 1, `0` if stride == 1
|
||||
- Length byte prefix bits indicate multi-byte length encoding
|
||||
|
||||
#### Detailed Encoding Logic (from source)
|
||||
|
||||
```c
|
||||
void AddRep()
|
||||
{
|
||||
if (stride == 0) return;
|
||||
|
||||
if (stride > 1) {
|
||||
color |= 0x80; // Set bit 7 to indicate run follows
|
||||
}
|
||||
rawData.Add(color);
|
||||
|
||||
if (stride <= 1) {
|
||||
// Single pixel: just the color byte
|
||||
return;
|
||||
}
|
||||
|
||||
if (stride <= 0x7f) { // 127
|
||||
// 1-byte length: [0rrrrrrr]
|
||||
rawData.Add((byte)stride);
|
||||
return;
|
||||
}
|
||||
|
||||
if (stride <= 0x3fff) { // 16383
|
||||
// 2-byte length: [10rrrrrr] [rrrrrrrr]
|
||||
rawData.Add((byte)((stride >> 8) | 0x80));
|
||||
rawData.Add((byte)stride);
|
||||
return;
|
||||
}
|
||||
|
||||
if (stride <= 0x1fffff) { // 2097151
|
||||
// 3-byte length: [110rrrrr] [rrrrrrrr] [rrrrrrrr]
|
||||
rawData.Add((byte)((stride >> 16) | 0xc0));
|
||||
rawData.Add((byte)(stride >> 8));
|
||||
rawData.Add((byte)stride);
|
||||
return;
|
||||
}
|
||||
|
||||
if (stride <= 0xfffffff) { // 268435455
|
||||
// 4-byte length: [1110rrrr] [rrrrrrrr] [rrrrrrrr] [rrrrrrrr]
|
||||
rawData.Add((byte)((stride >> 24) | 0xe0));
|
||||
rawData.Add((byte)(stride >> 16));
|
||||
rawData.Add((byte)(stride >> 8));
|
||||
rawData.Add((byte)stride);
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
#### Decoding Algorithm
|
||||
|
||||
```python
|
||||
def decode_ctb_rle(data: bytes, width: int, height: int) -> bytes:
|
||||
pixels = bytearray(width * height)
|
||||
pixel_pos = 0
|
||||
i = 0
|
||||
|
||||
while i < len(data):
|
||||
color_byte = data[i]
|
||||
i += 1
|
||||
|
||||
# Extract 7-bit color and expand back to 8-bit.
|
||||
# Non-zero levels map to odd values so 0x7F becomes 0xFF.
|
||||
grey7 = color_byte & 0x7F
|
||||
color = 0 if grey7 == 0 else (grey7 << 1) | 1
|
||||
|
||||
# Check if run follows (bit 7 set)
|
||||
if (color_byte & 0x80) == 0:
|
||||
# Single pixel
|
||||
pixels[pixel_pos] = color
|
||||
pixel_pos += 1
|
||||
continue
|
||||
|
||||
# Multi-pixel run: decode length
|
||||
length_byte = data[i]
|
||||
i += 1
|
||||
|
||||
if (length_byte & 0x80) == 0:
|
||||
# 1-byte length (7 bits)
|
||||
stride = length_byte
|
||||
elif (length_byte & 0x40) == 0:
|
||||
# 2-byte length (14 bits)
|
||||
stride = ((length_byte & 0x3F) << 8) | data[i]
|
||||
i += 1
|
||||
elif (length_byte & 0x20) == 0:
|
||||
# 3-byte length (21 bits)
|
||||
stride = ((length_byte & 0x1F) << 16) | (data[i] << 8) | data[i+1]
|
||||
i += 2
|
||||
else:
|
||||
# 4-byte length (28 bits)
|
||||
stride = ((length_byte & 0x0F) << 24) | (data[i] << 16) | (data[i+1] << 8) | data[i+2]
|
||||
i += 3
|
||||
|
||||
# Fill pixels
|
||||
for _ in range(stride):
|
||||
pixels[pixel_pos] = color
|
||||
pixel_pos += 1
|
||||
|
||||
return pixels
|
||||
```
|
||||
|
||||
#### Encryption (Optional)
|
||||
|
||||
If the CTB header encryption seed is non-zero, RLE data is XORed with a per-layer key stream derived from that seed:
|
||||
|
||||
**Encryption Algorithm (from ChituboxFile.cs:2227-2248):**
|
||||
```c
|
||||
void LayerRleCryptBuffer(uint seed, uint layerIndex, byte[] input)
|
||||
{
|
||||
if (seed == 0) return;
|
||||
|
||||
uint init = seed * 0x2d83cdac + 0xd8a83423;
|
||||
uint key = (layerIndex * 0x1e1530cd + 0xec3d47cd) * init;
|
||||
|
||||
int index = 0;
|
||||
for (int i = 0; i < input.Length; i++)
|
||||
{
|
||||
byte k = (byte)(key >> (8 * index));
|
||||
index++;
|
||||
|
||||
if ((index & 3) == 0) {
|
||||
key += init;
|
||||
index = 0;
|
||||
}
|
||||
|
||||
input[i] = (byte)(input[i] ^ k);
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
**Key Generation:**
|
||||
```
|
||||
init = seed * 0x2D83CDAC + 0xD8A83423
|
||||
key_base = (layerIndex * 0x1E1530CD + 0xEC3D47CD) * init
|
||||
|
||||
For each 4-byte block:
|
||||
XOR with bytes from key_base (little-endian)
|
||||
After 4 bytes, update: key_base += init
|
||||
```
|
||||
|
||||
#### Anti-Aliasing Support
|
||||
|
||||
CTB format supports 7-bit grayscale (128 levels), enabling smooth anti-aliasing:
|
||||
- 0x00 = fully masked (black)
|
||||
- 0x7F = fully exposed (white)
|
||||
- 0x01-0x7E = partial exposure (anti-aliasing)
|
||||
|
||||
#### Example Encodings
|
||||
|
||||
**Example 1: Single white pixel**
|
||||
```
|
||||
Input: 1 pixel at value 255
|
||||
Encoded: 7F
|
||||
- grey7 = 255 >> 1 = 127 = 0x7F
|
||||
- stride = 1, so bit 7 stays clear
|
||||
- Output: [0x7F] (1 byte)
|
||||
```
|
||||
|
||||
**Example 2: Run of 100 white pixels**
|
||||
```
|
||||
Input: 100 pixels at value 255
|
||||
Encoded: FF 64
|
||||
- grey7 = 127 = 0x7F
|
||||
- stride = 100 = 0x64
|
||||
- 100 <= 127, so 1-byte length
|
||||
- color with bit 7 set: 0x7F | 0x80 = 0xFF
|
||||
- Output: [0xFF] [0x64] (2 bytes)
|
||||
```
|
||||
|
||||
**Example 3: Run of 500 gray pixels (value 128)**
|
||||
```
|
||||
Input: 500 pixels at value 128
|
||||
Encoded: C0 81 F4
|
||||
- grey7 = 128 >> 1 = 64 = 0x40
|
||||
- stride = 500 = 0x1F4
|
||||
- 500 > 127 and <= 16383, so 2-byte length
|
||||
- color with bit 7: 0x40 | 0x80 = 0xC0
|
||||
- length high: (500 >> 8) | 0x80 = 0x01 | 0x80 = 0x81
|
||||
- length low: 500 & 0xFF = 0xF4
|
||||
- Output: [0xC0] [0x81] [0xF4] (3 bytes)
|
||||
```
|
||||
|
||||
**Example 4: Run of 20000 pixels**
|
||||
```
|
||||
Input: 20000 pixels at value 200
|
||||
Encoded: E4 C0 4E 20
|
||||
- grey7 = 200 >> 1 = 100 = 0x64
|
||||
- stride = 20000 = 0x4E20
|
||||
- 20000 > 16383, so 3-byte length
|
||||
- color: 0x64 | 0x80 = 0xE4
|
||||
- length encoding: 0x4E20 with 0xC0 prefix
|
||||
- Byte 0: ((0x4E20 >> 16) & 0x1F) | 0xC0 = 0xC0
|
||||
- Byte 1: (0x4E20 >> 8) & 0xFF = 0x4E
|
||||
- Byte 2: 0x4E20 & 0xFF = 0x20
|
||||
- Output: [0xE4] [0xC0] [0x4E] [0x20] (4 bytes)
|
||||
```
|
||||
|
||||
#### Key Differences from Simple RLE125
|
||||
|
||||
| Feature | Simple RLE125 | CTB Variable RLE |
|
||||
|---------|---------------|------------------|
|
||||
| **Color depth** | 8-bit (0-255) | 7-bit (0-127) |
|
||||
| **Max run (1-byte)** | 125 | 127 |
|
||||
| **Max run (total)** | 125 | 268,435,455 |
|
||||
| **Bytes per run** | 2 (fixed) | 1-5 (variable) |
|
||||
| **Single pixel** | 2 bytes | 1 byte |
|
||||
| **Anti-aliasing** | Binary or limited | Full 7-bit grayscale |
|
||||
| **Encryption** | No | Optional per-layer XOR |
|
||||
| **Compression** | Moderate | Better for long runs |
|
||||
|
||||
#### Implementation Recommendations
|
||||
|
||||
1. **Decoding CTB:**
|
||||
- Read color byte
|
||||
- Check bit 7 for run flag
|
||||
- If clear: single pixel
|
||||
- If set: decode variable-length stride
|
||||
- Apply encryption if seed != 0
|
||||
|
||||
2. **Encoding CTB:**
|
||||
- Quantize to 7-bit: `grey7 = pixel >> 1`
|
||||
- Group consecutive identical pixels
|
||||
- Encode with optimal byte count (1-5 bytes)
|
||||
- Apply encryption if required
|
||||
|
||||
3. **Encryption Handling:**
|
||||
- Always check the CTB header encryption seed
|
||||
- If non-zero, decrypt before RLE decode
|
||||
- Use layer-specific key derivation
|
||||
|
||||
---
|
||||
|
||||
## Issue 2: .pm4n Version Classification - AMBIGUOUS
|
||||
|
||||
### Current Status in UVtools
|
||||
|
||||
**Extension Registration:**
|
||||
```c
|
||||
// AnycubicFile.cs:1058
|
||||
new(typeof(AnycubicFile), "pm4n", "Photon Mono 4 (PM4N)")
|
||||
```
|
||||
|
||||
**Machine Mapping:**
|
||||
```c
|
||||
// AnycubicFile.cs:1731-1733
|
||||
if (FileEndsWith(".pm4n"))
|
||||
{
|
||||
return AnyCubicMachine.PhotonMono4;
|
||||
}
|
||||
```
|
||||
|
||||
**Version Mapping:**
|
||||
```c
|
||||
// AnycubicFile.cs:1155-1191
|
||||
public override uint[] GetAvailableVersionsForExtension(string? extension)
|
||||
{
|
||||
switch (extension)
|
||||
{
|
||||
case "pm3n":
|
||||
case "pm5":
|
||||
case "px6s":
|
||||
return [VERSION_517]; // ← pm3n, pm5, px6s are v517
|
||||
|
||||
case "pm5s":
|
||||
case "m5sp":
|
||||
return [VERSION_518]; // ← pm5s, m5sp are v518
|
||||
|
||||
// NOTE: .pm4n is NOT in the switch statement!
|
||||
|
||||
default:
|
||||
return AvailableVersions; // ← .pm4n falls through here
|
||||
}
|
||||
}
|
||||
|
||||
// AvailableVersions = [VERSION_1, VERSION_515, VERSION_516, VERSION_517, VERSION_518]
|
||||
```
|
||||
|
||||
### The Ambiguity
|
||||
|
||||
**`.pm4n` extension:**
|
||||
- ✓ Registered as valid extension
|
||||
- ✓ Maps to PhotonMono4 machine
|
||||
- ✗ **NOT** explicitly assigned to any version in `GetAvailableVersionsForExtension`
|
||||
- Returns all versions: `[1, 515, 516, 517, 518]`
|
||||
|
||||
### Possible Interpretations
|
||||
|
||||
1. **Oversight:** UVtools forgot to add .pm4n to the v517 case block
|
||||
2. **Intentional:** .pm4n can legitimately be multiple versions (firmware evolution)
|
||||
3. **Unknown:** Insufficient real-world fixtures to determine correct version
|
||||
|
||||
### User Implementation Note
|
||||
|
||||
**User's current implementation treats `.pm4n` as v517**, which is:
|
||||
- ✓ Consistent with similar naming (.pm3n, .pm5 are v517)
|
||||
- ✓ Logical based on product generation
|
||||
- ⚠️ **UNVERIFIED** by UVtools code (could be any version)
|
||||
|
||||
### Recommendations
|
||||
|
||||
**For Implementation:**
|
||||
```c
|
||||
// Conservative approach (allow multiple versions):
|
||||
if (extension == "pm4n") {
|
||||
return [VERSION_515, VERSION_516, VERSION_517];
|
||||
}
|
||||
|
||||
// Aggressive approach (assume v517 based on naming):
|
||||
if (extension == "pm4n") {
|
||||
return [VERSION_517];
|
||||
}
|
||||
```
|
||||
|
||||
**For Validation:**
|
||||
1. Obtain real .pm4n fixture files from PhotonMono4 printer
|
||||
2. Decode header and check `FileMarkSettings.Version` value
|
||||
3. Verify header table length (92 bytes = v517, 96 bytes = v518)
|
||||
4. Verify layer definition entries remain 32 bytes each; v518 may also include `SUBIMGS` sublayer entries
|
||||
5. Document actual version found in fixtures
|
||||
|
||||
**Fixture Verification Checklist:**
|
||||
- [ ] Acquire .pm4n file from PhotonMono4
|
||||
- [ ] Verify file mark starts with ASCII `ANYCUBIC`
|
||||
- [ ] Read version at offset 0x0C (little-endian uint32 in the `FileMark`)
|
||||
- [ ] Check `HEADER` table length (92 = v517, 96 = v518)
|
||||
- [ ] Check layer definition entries are 32 bytes each
|
||||
- [ ] Check whether `SUBIMGS` and `PREVIEW2` tables are present
|
||||
- [ ] Document findings
|
||||
|
||||
### Comparison with Similar Extensions
|
||||
|
||||
| Extension | Machine | Version in Code | Logic |
|
||||
|-----------|---------|-----------------|-------|
|
||||
| .pm3n | PhotonMono2 | 517 (explicit) | ✓ Defined |
|
||||
| **.pm4n** | **PhotonMono4** | **??? (default all)** | ⚠️ **Ambiguous** |
|
||||
| .pm5 | PhotonMonoM5 | 517 (explicit) | ✓ Defined |
|
||||
| .pm5s | PhotonMonoM5s | 518 (explicit) | ✓ Defined |
|
||||
|
||||
**Pattern suggests:** .pm4n should likely be v517, but this is **NOT verified in UVtools source**.
|
||||
|
||||
---
|
||||
|
||||
## Updated Classification
|
||||
|
||||
### Anycubic Modern Formats (CORRECTED)
|
||||
|
||||
| Extension | Machine | Version | Status |
|
||||
|-----------|---------|---------|--------|
|
||||
| .pm3n | PhotonMono2 | 517 | ✓ Verified |
|
||||
| **.pm4n** | **PhotonMono4** | **517 (assumed)** | **⚠️ UNVERIFIED** |
|
||||
| .pm5 | PhotonMonoM5 | 517 | ✓ Verified |
|
||||
| .px6s | PhotonMonoX6Ks | 517 | ✓ Verified |
|
||||
| .pm5s | PhotonMonoM5s | 518 | ✓ Verified |
|
||||
| .m5sp | PhotonMonoM5sPro | 518 | ✓ Verified |
|
||||
|
||||
### Action Items for Documentation
|
||||
|
||||
1. **CTB RLE:** Update main reference with variable-length encoding details
|
||||
2. **.pm4n:** Mark as "Assumed v517, requires fixture validation"
|
||||
3. **Testing:** Add note about lack of test fixtures in UVtools repository
|
||||
4. **Encryption:** Document optional per-layer XOR encryption for CTB
|
||||
|
||||
---
|
||||
|
||||
## Code References
|
||||
|
||||
**CTB RLE Encoding:**
|
||||
- Implementation: `ChituboxFile.cs:825-908` (EncodeCtbImage)
|
||||
- Decoding: `ChituboxFile.cs:685-745` (DecodeImage)
|
||||
- Encryption: `ChituboxFile.cs:2220-2248` (LayerRleCrypt)
|
||||
|
||||
**Anycubic Versions:**
|
||||
- Extension mapping: `AnycubicFile.cs:1155-1191` (GetAvailableVersionsForExtension)
|
||||
- Machine detection: `AnycubicFile.cs:1731-1733` (FileEndsWith check)
|
||||
- Version constants: `AnycubicFile.cs:30-33` (VERSION_515-518)
|
||||
|
||||
---
|
||||
|
||||
## Summary
|
||||
|
||||
**CTB RLE:**
|
||||
- ❌ Previous: Simple RLE125 (2 bytes/run, max 125)
|
||||
- ✅ Correct: Variable-length 7-bit grayscale RLE (1-5 bytes/run, max 268M, optional encryption)
|
||||
|
||||
**.pm4n Version:**
|
||||
- ❌ Previous: Listed under v517 without caveat
|
||||
- ✅ Correct: Ambiguous in UVtools (defaults to all versions), **assumed v517 pending fixture validation**
|
||||
|
||||
**Document Status:** Ready for integration into main reference with caveats noted.
|
||||
|
|
|
|||
File diff suppressed because it is too large
Load diff
Loading…
Reference in a new issue