revise calculation of JPEG buffer #35
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ladyada
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Feb 5, 2025
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Updating https://github.com/adafruit/Adafruit_CircuitPython_OV5640 to 1.2.4 from 1.2.3: > Merge pull request adafruit/Adafruit_CircuitPython_OV5640#35 from jerryneedell/jerryn_buffer Updating https://github.com/adafruit/Adafruit_CircuitPython_RGB_Display to 3.13 from 3.12.7: > Merge pull request adafruit/Adafruit_CircuitPython_RGB_Display#129 from adafruit/gc9a01a Updating https://github.com/adafruit/Adafruit_CircuitPython_MiniMQTT to 7.11.5 from 7.11.4: > Merge pull request adafruit/Adafruit_CircuitPython_MiniMQTT#238 from dhalbert/test_recv_timeout
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Changes to Adafruit_CircuitPython_OV5640 doubled the memory usage for a given quality setting. This makes the latest release of in CircuitPython incompatible with the previous quality setting=3 + colorspace=adafruit_ov5640.OV5640_COLOR_JPEG due to that working out an an allocation size of 204800. This is too much for the first Pico. Here is the breaking change: adafruit/Adafruit_CircuitPython_OV5640#35 Quality 4 is still too large at 153,600 bytes. Quality 5 using 122,880 works.
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Addresses #29
Change the calculation of the JPEG capture buffer to avoid corrupted captures.
the old calculation was width*height/quality
but this often resulted in the buffer being too small, especially for higher quality (lower resolution) images.
the new calculation doubles the size:
2*width*height/qualityThis may be overkill, but does seem to work over a wide range of JPEG sizes and qualities.
We can discuss reducing it and accept more risk of errors.
setting the buffer to
width*height//5also seems to work, but seems very difficult to explain...These changes were tested with a Pico2W.
Using a PicoW there are still severe memory constraints. I was only able to use JPEG images of 160x120 (QQVGA)
I was also able to capture JPEG images and write to an SD on a Pico.
Using the PicoW to capture an image and send it to AIO was not viable, in my experience.
That is why I moved to the Pico2W to work on this.