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Hi,

Any chance to make pyAPNG available on Conda Forge?

There is a rather serious issue when handling large PNG files at the moment. The following code:

from apng import APNG

im = APNG.open("test_large.apng")
im.frames[0][0].save("frame0.png")

generates broken png files for individual frames, if a frame contain more that one data chunk.
cf. #12 for a fix.

How to do it?

I read in an image, and print out it's frames (as in your example). All output files have that error.

Hi

actualliy when run python setup.py install --root=<foo> --optimize, the test folder is also installed

please leave it out from installation

greetings

I got an APNG from here.

I tried extracting the frames using this, but found that there is a frame being extracted in only 1x1. Here's the extraction result

Then I used APNG Disassembler to extract the frames, I got that "missing frame".

It appears that frame 6 and 8 are the same, but frame 8 cannot be extracted using this. Here's the chunk structure acquired by pngcheck v2.3.0:

That fdAT at 0x226 with length only 17 is the missing one. I tried finding information by inspecting the documentation of both APNG and PNG, but cannot find any information about potentially reusing the frame. All other chunks seems also not indicating this reuse.

How to handle this case?

Note

• The APNG seems to be assembled by APNG Assembler, which there's also a counterpart APNG Disassembler.
• I've inspected the source code of APNG Disassembler, which can be found here (v2.9). It's using libpng to read the png, which I then inspected their documentation, but still found nothing about the reuse.

Is it possible to pass a repeat count to the apng file? At the moment the repeat count stands at "-1" for repeat forever? Does the specification for apng even support repeat count?

Been banging my head on writing an apng extraction myself. It somewhat works, but I run into issues with this file. Looks like your method runs into issues too..

The file was manually edited by the author to set the number of frames to 1. The technique of looking at the chunks themselves obviously gets by that. However, many of the images that get pulled out are corrupt.

My knowledge of PNG isn't the greatest, so I'm not sure if they're corrupt due to some process error in extracting or if they started that way... Either way, both of our extraction approaches cause some of the output files to be errored.

Whenever I try to use this I get the error code integer out of range for 'I' format code

e.g.

APNG.from_files(images, delay=100).save('test.png')

Where images is a list of filepaths returns this error.

Python 2.7

I've had the same results with Python 2.7 and 3.6.

import apng
method_list = [func for func in dir(apng) if callable(getattr(apng, func))]
print(method_list)
[]

Specifically,

from apng import APNG
"Cannot find reference 'APNG' in apng.py."

Maybe I am missing a dependency? I installed apng from the terminal for 3.6 and using the GUI in PyCharm for 2.7.