A DSL for image and video transformation.
wwwwait^0.2 >> (wwwwait^0.2 | hflip) > "wwwwaiting.gif"
- Currently implemented: tree-walk interpreter with the base operators and named functions below, backed by
pillow - Future:
- More comprehensive handling of number types (
ms,s,%) - Aliasing / assign names to pipelines
- Custom functions defined by GLSL shaders
- More comprehensive handling of number types (
Input images and videos are referenced with automatically defined variables. For example, when heddle is run in a directory with im.gif, im^2 | hflip creates a copy at 2x speed, flipped horizontally.
| op | description |
|---|---|
f(...) |
function; named transform/source with parameters. see below |
[t0:t1, y0:y1, x0:x1] |
slice (time, y, x) |
^k |
speed, where k is a float; negative values reverse input |
| |
pipe to compose transforms |
over |
composites left and right inputs on top of each other |
&, / |
horizontal and vertical stacking layout, respectively |
>> |
temporal concatenation, left before right. supports transitions |
Functions are used for transformations not covered by the operators and for transition markers used inside a timeline.
| fn | description |
|---|---|
text(str, pos) |
displays the given str in white over the input, aligned according to pos |
blur(stdev) |
applies a Gaussian blur |
scale(factor) |
scales input by single factor on width and height |
resize(w, h) |
scales input to exact width and height |
reverse() |
reverses a clip, alias to ^-1 |
dissolve(sec) |
inserts a dissolve lasting sec seconds between neighboring clips in a >> timeline |
text positions may be written as bare names. The supported descriptive names are TOP_LEFT, TOP, TOP_RIGHT, LEFT, CENTER, RIGHT, BOTTOM_LEFT, BOTTOM, and BOTTOM_RIGHT; two-letter forms such as TL, TC, and BR are also accepted.
A dissolve must appear between two clips, for example a >> dissolve(0.5) >> b. Its frames are sampled at intervals of at most 100ms, with the final interval shortened so the transition has the exact requested duration.