Open source and universal binnary file format for mSLA/DLP (.odlp)

This file format aims for simplicity and universal file format for low-end printers that can't take a ZIP + PNG slices approach due the incapacity of CPU to process such data schemes.

Implementation requesites

Open-source file format
Document the changes and revisions, as well the reserved table if any
Universal: the file and revisions should always be compatible with any firmware that take this file
No encrypted files: The data should be plain and easy to access
No property or changed variant of the file format should exists!
Machine follows sequential gcode commands

Printer firmware checks (can print this file?)

Marker == "ODLPTiCo" - This is a double check if file is really a .odlp beside it extension, case sensitive compare.
Compare machine resolution with file resoltuion.
Can use ImageDataType? For example, if processor is unable to process PNG images, trigger an error and dont allow to continue.
Parse gcode and check for problems, such as, print on a position out of printer Z range.

Printer firmware layer data adquisiton

Machine firmware detects M6054 i gcode command.
Goes to the layer definition table at the i index given by the M6054 command.
Gets the image address and jumps to it.
Start to read and buffer the image to the LCD.
Jump back to the resume position and continue to execute the gcode.

Note: Printer only continue to execute the next gcode command after the image is displayed/buffered. When using a sencond board to display the image, it must send a OK back in order to resume the gcode execution.

Software data adquisiton

For slicers and other programs, data and per layer settings should be parsed from gcode.

In file optimizations

When generating the file, layers that share the same image data, may reuse that data instead of duplicate the image. This allow to spare a good amount of data when file contains multiple layers that share same image over and over, for example, functional parts. See example on file sample bellow at [Layer 3]. While this is optional and either way it must be valid to print, is highly recommended to hash the layers.

Draft 1

[File]
Marker=ODLPTiCo (char[8]) Extra validation beside file extension, constant
Version=1 (ushort) File format revision
ModifiedTime=1626451007 (uint) UNIX Timestamp when file gets modified
ModifiedBy=UVtools v2.15.0\0\0\0\0\0\0\0.. (char[50] fixed!) program/slicer who last modified the file

[Header]
HeaderTableSize=sizeof(header) (uint), excluding this field
MachineZ=130.00 (float)
DisplayWidth=68.04 (float)
DisplayHeight=120.96 (float)
ResolutionX=1080 (uint)
ResolutionY=1080 (uint)
MirrorX=1 (byte) 0 = false | 1 = true
MirrorY=0 (byte) 0 = false | 1 = true
PreviewDataType=RGB16\0\0\0 (char[8]) compressed image data type, eg: RLE-XXX or RGB16 or PNG or JPG or BITMAP OR other?
LayerDataType=PNG\0\0\0\0\0 (char[8]) compressed image data type, eg: RLE-XXX or PNG or JPG or BITMAP OR other?
NumberOfPreviews=2 (byte) Number of previews/thumbnails on this file
LayerCount=1000 (uint) Total number of layers
LayerDefinitionsAddress=00000 (uint) Address for layer definition
GCodeAddress=000000 (uint) gcode text address, size = Total file size - GCodeAddress
# Dynamic text fields
MachineNameSize=sizeof(MachineName) (ushort)
MachineName=Phrozen Sonic Mini (string)
# HEADER ends here

[CustomTable]
CustomTableSize=4 (uint) Number reserved of bytes for a custom table, this can be used for custom use of each brand, but not important for general file format
# This can be used to store slicer specific settings or additional information
# Still both printer and software must not depend on this
ExampleOfCustomField=1001 (uint)

[Preview 1]
PreviewTableSize=8 (uint), Size of table excluding this field
ResolutionX=400 (ushort)
ResolutionY=400 (ushort)
PreviewDataSize=sizeof(DATA) (uint)
RLE/RGB16/PNG/JPG/BITMAP

[Preview 2]
PreviewTableSize=8 (uint), Size of table excluding this field
ResolutionX=400 (ushort)
ResolutionY=800 (ushort)
PreviewDataSize=sizeof(DATA) (uint)
RLE/RGB16/PNG/JPG/BITMAP

[LayerDefinitions]
[Layer 1]
LayerTableSize=4 (uint), Size of table excluding this field
DataAddress=0000

[Layer 2]
LayerTableSize=4 (uint), Size of table excluding this field
DataAddress=1111

[Layer 3]
LayerTableSize=4 (uint), Size of table excluding this field
DataAddress=1111 (Identical layers can point to the same data if they share the same image, sparing space on file)

DataSize=sizeof(RLE) (uint)
RLE/PNG/JPG/BITMAP of layer 1

DataSize=sizeof(RLE) (uint)
RLE/PNG/JPG/BITMAP of layer 2

[GCode]
GCodeSize=sizeof(gcode) (uint) gcode text length
# Following by raw text
;START_GCODE_BEGIN
G21;Set units to be mm
G90;Absolute positioning
M106 S0;Turn LED OFF
M17;Enable motors
;<Slice> Blank
G28 Z0;Home Z
;END_GCODE_BEGIN

;LAYER_START:0
;PositionZ:0.05mm
M6054 0;Show image by layer index, to lookup on layer definition
G0 Z5.05 F60;Z Lift
G0 Z0.05 F150;Retract to layer height
G4 P10000;Stabilization delay
M106 S255;Turn LED ON
G4 P80000;Cure time/delay
M106 S0;Turn LED OFF
;<Slice> Blank
;LAYER_END

;START_GCODE_END
M106 S0;Turn LED OFF
G0 Z180 F150;Move Z
M18;Disable motors
;END_GCODE_END
;<Completed>

Notes:

Previews start address = file table size + header table size + custom table size
Header dont need much information, everything can be parsed from gcode!

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