The easiest thing to implement was to use the i/j numbers, but they were not
directly related to image x/y coordinates. This may slow things down a tiny
little bit, but it looks much better.
* Increase colorspace conversion efficiency.
This not only avoids a function call, it avoids the time-consuming
switch statement in conver_pixel (replacing it with a single
conditional on the byteswap flag + accounting for BGR/RGB during
palette creation)
* Buffer all the bytes of a single frame together. By reducing
low level write calls we get a decent speed increase even though
it increases data-shuffling a bit.
Together with some other changes that enable "double buffered" camera
capture, this gets me to 8.8fps capturing QVGA (320x240) gifs and
11fps capturing 240x240 square gifs.
This involves:
* Adding a new "L8" colorspace for colorconverters
* factoring out displayio_colorconverter_convert_pixel
* Making a minimal "colorspace only" version of displayio for the
unix port (testing purposes)
* fixing an error message
I only tested writing B&W animated images, with the following script:
```python
import displayio
import gifio
with gifio.GifWriter("foo.gif", 64, 64, displayio.Colorspace.L8) as g:
for i in range(0, 256, 14):
data = bytes([i, 255-i] * 32 + [255-i, i] * 32) * 32
print("add_frame")
g.add_frame(data)
# expected to raise an error, buffer is not big enough
with gifio.GifWriter("/dev/null", 64, 64, displayio.Colorspace.L8) as g:
g.add_frame(bytes([3,3,3]))
```
This increases write rates (of gifio from #5490) from about 2.4fps to over
5fps by making more efficient use of the SD card protocol.
Because of details of oofatfs, it usually manages 64 writes in a single
CMD25, then two writes in a different area of the SD card (presumably,
filesystem metadata). I couldn't find where to increase "64" to a higher
number. This may depend on the allocation size of the filesystem.
I tried preallocating too, but oddly it significantly lowered the write
rate.
Any trailing data is committed when the file is close()d, or when
the `sync` method of the SDCard object is called.
Jeff Epler
Dan Halbert
Dan Halbert
Limor "Ladyada" Fried
Jeff Epler
Jeff Epler
Hosted Weblate
Scott Shawcroft
root
Max Holliday
Pierre Constantineau
arturo182
microDev
Jonny Bergdahl
Wellington Terumi Uemura