[macOS] RuntimeError: Could not get number of frames

[cuteguy]

Deface is quite handy for processing individual images, but it consistently encounters errors when I attempt to process MP4 files, and I'm uncertain of the underlying cause.

OS: macOS sonoma 14.3
Chip: Apple M1 Pro
Python Version: Python 3.11.7

Traceback (most recent call last):
  File "/opt/homebrew/bin/deface", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/opt/homebrew/lib/python3.11/site-packages/deface/deface.py", line 398, in main
    video_detect(
  File "/opt/homebrew/lib/python3.11/site-packages/deface/deface.py", line 142, in video_detect
    nframes = reader.count_frames()
              ^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/lib/python3.11/site-packages/imageio/plugins/ffmpeg.py", line 385, in count_frames
    return cf(self._filename)[0]
           ^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/lib/python3.11/site-packages/imageio_ffmpeg/_io.py", line 187, in count_frames_and_secs
    raise RuntimeError("Could not get number of frames")  # pragma: no cover
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: Could not get number of frames

[mdraw]

Thanks for reporting this issue. Seems to be related to imageio/imageio-ffmpeg#99. As a workaround you can just replace this line

deface/deface/deface.py

Line 142 in 1e6a87f

nframes = reader.count_frames()

with

nframes = None

And everything should work except for the progress bar.
Alternatively try downgrading ffmpeg to an older version.

[Cogitarian]

Change in lib/python3.9/site-packages/imageio_ffmpeg/_io.py function for counting frames from ffmpeg to ffprobe, I've tested it on macos and it works:

def count_frames_and_secs(path):
"""
Get the number of frames and number of seconds for the given video
file. Note that this operation can be quite slow for large files.

Disclaimer: I've seen this produce different results from actually reading
the frames with older versions of ffmpeg (2.x). Therefore I cannot say
with 100% certainty that the returned values are always exact.
"""
# https://stackoverflow.com/questions/2017843/fetch-frame-count-with-ffmpeg

if isinstance(path, pathlib.PurePath):
    path = str(path)
if not isinstance(path, str):
    raise TypeError("Video path must be a string or pathlib.Path.")

cmd = ['ffprobe','-v','error','-select_streams','v:0','-count_packets','-show_entries','stream=nb_read_packets','-of','csv=p=0', path]
try:
    out = subprocess.check_output(cmd, stderr=subprocess.STDOUT, **_popen_kwargs())
except subprocess.CalledProcessError as err:
    out = err.output.decode(errors="ignore")
    raise RuntimeError(
        "FFMPEG call failed with {}:\n{}".format(err.returncode, out)
    )

# Note that other than with the subprocess calls below, ffmpeg wont hang here.
# Worst case Python will stop/crash and ffmpeg will continue running until done.

nframes = out
return nframes

raise RuntimeError("Could not get number of frames")  # pragma: no cover