Report progress during batch processing

[mundodisco8]

Hi,

I've been playing with the module and so far it's proven to be really useful, thanks for your work.

I'm renaming some files based on their date of creation. Sometimes, I have to process folders with a couple thousand files. I used to do a "for file in files: process(file)" but that took hours, and found that ExifTool is capable of doing batch processing itself, WAY FASTER (minutes), so I use the execute_json to do the batch processing for me.

Nevertheless, it still takes minutes, and was wondering if there's a way to report progress during processing, or at least an "spinner".

[sylikc]

So, currently PyExifTool doesn't support any type of progress. I could envision doing something like a callback to dump out the os.read() somewhere... but I'm not necessarily sure this would be helpful to the caller.

pyexiftool/exiftool/exiftool.py

Lines 125 to 135 in e54f96c

	while not _get_buffer_end(output_list, endswith_count).strip().endswith(b_endswith):
	if constants.PLATFORM_WINDOWS:
	# windows does not support select() for anything except sockets
	# https://docs.python.org/3.7/library/select.html
	output_list.append(os.read(fd, block_size))
	else: # pytest-cov:windows: no cover
	# this does NOT work on windows... and it may not work on other systems... in that case, put more things to use the original code above
	inputready, outputready, exceptready = select.select([fd], [], [])
	for i in inputready:
	if i == fd:
	output_list.append(os.read(fd, block_size))

The issue is that the os.read() is given raw bytes back. These are neither decoded, nor does pyexiftool know exactly how much data is supposed to be returned.

If we could come up with something that might be useful, it could be implemented. As it stands, it's a bit difficult to find a good implementation that has a general use case

[mantered]

exiftool has a "-progress" flag, could that be used to report back some progress?
At the moment I'm using the exiftool command and pipe the progress to the terminal,
since PyExifTool has no progress report.