WebP plugin save animated webp need default duration value

[jeevic]

What did you do?

i only convert a animate gif format to animate webP format

What did you expect to happen?

it can convert success

What actually happened?

python3.7/site-packages/PIL/WebPImagePlugin.py" , line 292, in _save_all timestamp += duration TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType'

What are your OS, Python and Pillow versions?

• OS: macos Monterey version 12.2.1
• Python: 3.7.11
• Pillow: 8.4.0

through debug, i know the reason is that pillow open gif image use method im.info.get("duration") is null, when i convert to webP format with no Coustom duration param。 because duration come from duration = im.encoderinfo.get("duration", im.info.get("duration")) [WebPImagePlugin.py line 195] be NoneType, it will traceback in WebPImagePlugin.py 292

                # Update timestamp and frame index
                if isinstance(duration, (list, tuple)):
                    timestamp += duration[frame_idx]
                else:
                    timestamp += duration

traceback:

Traceback (most recent call last):
  File "/Users/jeevi/Documents/WWW/study/python/pillow_img/img/img.py", line 198, in <module>
    im.save(bts, "webP", save_all=True, quality=75,  optimize=True)
  File "/Users/jeevi/Documents/WWW/study/python/pillow_img/python/lib/python3.7/site-packages/PIL/Image.py", line 2240, in save
    save_handler(self, fp, filename)
  File "/Users/jeevi/Documents/WWW/study/python/pillow_img/python/lib/python3.7/site-packages/PIL/WebPImagePlugin.py", line 292, in _save_all
    timestamp += duration
TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType'

i think duration need a default value when not get

here is my code:

file = "./YD_cnt_11_019CS3rXgAIN.gif"
    
    with Image.open(file) as im:
        print(im.format, im.size, im.mode, getattr(im, "is_animated", False), getattr(im, "n_frames", 1),
              getattr(im, "n_frames", 1) // 2)
        bts = BytesIO()
        im.save(bts, "webP", save_all=True, quality=75,  optimize=True)
        print("长度:{} \n".format(len(bts.getvalue())))
        with open("YD_cnt_11_019CS3rXgAIN.gif.webp", "wb") as f:
            f.write(bts.getvalue())
        t2 = time.time()
        cost = int(round(t2 * 1000)) - int(round(t * 1000))
        print("耗时:{}ms\n".format(cost))

the image file in my github : https://github.com/jeevi-cao/study/blob/master/python/YD_cnt_11_019CS3rXgAIN.gif

[radarhere]

You're right. I've created PR #6140 to resolve this.

[jeevic]

ok thank you