A .sif file is the XML representation of a canvas. It holds the canvas's metadata, such as width and height, as well as information about its layers. Typically, a Synfig production comprises many .sif files joined in a sequence or nested within each other.
The .sif format is formidably complex and evolving. It is implementation-defined rather than spec-defined. Therefore, you should take everything on this page with a grain of salt. Indeed, the implementation can change at any point.
There are no plans to freeze the format.
The .sif format is implemented by the following file:
The format as of January 2016
.sif files aren't always self-contained. They can import (read: link to) other .sif files, which creates a dependency of one on the other. This may seem strange to animators who use Flash because, in Flash, importing something causes it to be embedded in the current animation.
One drawback of Synfig's approach is that .sif dependencies can be hard to track. A tool called RenderChan solves this problem.
Recursion of .sif files is prohibited.
Synfig recognizes .sifz as the extension of gzip-compressed .sif files. New and alternate implementations of .sif are urged to support this compression, although it is not required.
The top element of a .sif file is always a <canvas>.
<?xml version="1.0"?> <canvas version="0.1" width="300" height="350" xres="2952.7559" yres="2952.7559" view-box="-1.5 2.5 1.5 -1" antialias="2" fps="12" begin-time="0f" end-time="0f" bgcolor="0.5 0.5 0.5 1"> ... </canvas>
|Attribute||Default||What it is|
|version||no default, this attribute is required||0.1, always|
|width||720||the width of the canvas in pixels|
|height||480||the height of the canvas in pixels|
|xres||2835||the width of the canvas in pixels per meter|
|yres||2835||the height of the canvas in pixels per meter|
|view-box||-4 2.25 4 -2.25||the bounding coordinates of the canvas (left top right bottom)|
|antialias||2||how hard Synfig should try to antialias the image|
|fps||24||frames per second|
|begin-time||0||where on the timetrack should rendering start|
|end-time||0||what on the timetrack should rendering end|
|bgcolor||0.5 0.5 0.5 1.0||the color of the background in RGBA|
Inside a <canvas> you can find the following elements:
The short name of the canvas.
<canvas version="0.1"> ... <name>Aqua Sphere</name> ... </canvas>
A miscellaneous piece of metadata.
<canvas version="0.1"> ... <meta name="grid_show" content="1" /> ... </canvas>
The name of the canvas's author.
<canvas version="0.1"> ... <author>King Arthur</author> ... </canvas>
A human-readable description of the canvas.
<canvas version="0.1"> ... <desc>This aqua-colored sphere reminds me of something from Mac OS X.</desc> ... </canvas>