Bug 220317 – Certain webp files can't be displayed

• Component: Images
• Status: RESOLVED DUPLICATE

[Radek Šerý]

Created attachment 416983 [details]
Source file for conversion

Hi,
we have discovered that some webp images do not display properly (they don't display at all) in Safari 14 on macOS 11. In other browsers, these webp images render just fine, but Safari will only display placeholder image. The webp image itself can't be open in native macOS app for images either.

In the attachments, you can see two webp images, both converted with cwebp 1.1.0 (latest) binary utility. First one with quality=80, second one with quality=85. First one can't be displayed, the second one can be. There's also source png file attached.

This is the command used as well as the verbose output from cwebp utility for both conversions:

zipper:~$ cwebp -q 80 4942.png -o 4942-80.webp -v
Time to read input: 0.024s
Saving file '4942-80.webp'
Time to encode picture: 0.076s
File:      4942.png
Dimension: 1400 x 1110 (with alpha)
Output:    6132 bytes Y-U-V-All-PSNR 54.21 62.26 63.26   55.67 dB
           (0.03 bpp)
block count:  intra4:        302  (4.90%)
              intra16:      5858  (95.10%)
              skipped:      5498  (89.25%)
bytes used:  header:             85  (1.4%)
             mode-partition:   3507  (57.2%)
             transparency:       91 (99.0 dB)
 Residuals bytes  |segment 1|segment 2|segment 3|segment 4|  total
    macroblocks:  |       0%|       1%|       2%|      96%|    6160
      quantizer:  |      27 |      27 |      26 |      19 |
   filter level:  |       8 |       6 |      17 |      21 |
Lossless-alpha compressed size: 90 bytes
  * Header size: 19 bytes, image data size: 71
  * Lossless features used: PALETTE
  * Precision Bits: histogram=5 transform=5 cache=0
  * Palette size:   2



zipper:~$ cwebp -q 85 4942.png -o 4942-85.webp -v
Time to read input: 0.023s
Saving file '4942-85.webp'
Time to encode picture: 0.076s
File:      4942.png
Dimension: 1400 x 1110 (with alpha)
Output:    7208 bytes Y-U-V-All-PSNR 55.04 64.82 64.39   56.57 dB
           (0.04 bpp)
block count:  intra4:        400  (6.49%)
              intra16:      5760  (93.51%)
              skipped:      5269  (85.54%)
bytes used:  header:            104  (1.4%)
             mode-partition:   3712  (51.5%)
             transparency:       91 (99.0 dB)
 Residuals bytes  |segment 1|segment 2|segment 3|segment 4|  total
    macroblocks:  |       0%|       1%|       2%|      96%|    6160
      quantizer:  |      20 |      20 |      18 |      13 |
   filter level:  |       7 |       5 |       8 |      13 |
Lossless-alpha compressed size: 90 bytes
  * Header size: 19 bytes, image data size: 71
  * Lossless features used: PALETTE
  * Precision Bits: histogram=5 transform=5 cache=0
  * Palette size:   2

[Radek Šerý]

Created attachment 416984 [details]
This webp can't be displayed by macOS 11.1

[Radek Šerý]

Created attachment 416985 [details]
This webp displays correctly in macOS 11.1

[Alexey Proskuryakov]

Thank you for the report!

> The webp image itself can't be open in native macOS app for images either.

I'm provisionally duping this to bug 219977, which tracks a webp issue in an iOS release matching macOS 11.1. However, it would be best to report this to Apple via https://feedbackassistant.apple.com in case these are two different issues. Since this affects more than WebKit, this should be looked at by an expert.

*** This bug has been marked as a duplicate of bug 219977 ***