Exiv2

Google have proposed new image and movie file formats to address various deficiencies in the existing 2000+ known formats. We believe that the video format webm is already supported by our Matrovska implementation.

Gilles has been asking on behalf of Digicam for Exiv2 to support webp.

I’ve looked at libwebp from Google. I’ve built it and run some examples. This looks like a straight-forward task.

621 rmills@rmillsmbp:~ $ cp ~/Pictures/2015/WinterTrip/Austin/DSC_5900.jpg test.jpg; ls -alt test.jpg
-rw-r--r--  1 rmills  staff  7167602 22 Mar 22:23 test.jpg
622 rmills@rmillsmbp:~ $ exiv2 -pv test.jpg | wc                          # nice new test JPEG with 156 lines of metadata
     156    1091   10978
623 rmills@rmillsmbp:~ $ cwebp -metadata exif test.jpg -o test.webp       # convert the JPEG to WEBP while keeping the exif data in test.web
Saving file 'test.webp'
File:      test.jpg
Dimension: 6000 x 4000
Output:    420072 bytes Y-U-V-All-PSNR 42.59 47.79 47.70   43.73 dB
block count:  intra4: 45949
              intra16: 47801  (-> 50.99%)
              skipped block: 12523 (13.36%)
bytes used:  header:            281  (0.1%)
             mode-partition: 125371  (29.8%)
 Residuals bytes  |segment 1|segment 2|segment 3|segment 4|  total
    macroblocks:  |       2%|       6%|      13%|      76%|   93750
      quantizer:  |      36 |      36 |      30 |      23 |
   filter level:  |      15 |      31 |      32 |      20 |
Metadata:
  * EXIF data:     14854 bytes
624 rmills@rmillsmbp:~ $ ls -alt test.webp                                # a little smaller, eh?
-rw-r--r--  1 rmills  staff  434952 22 Mar 22:24 test.webp
626 rmills@rmillsmbp:~ $ webpmux -get exif test.webp -o - | exiv2 -pv -   # extract the metadata and pipe it through exiv2
Saved file - (14854 bytes)
0x010f Image        Make                        Ascii      18  NIKON CORPORATION
0x0110 Image        Model                       Ascii      12  NIKON D5300
...
0x0202 Thumbnail    JPEGInterchangeFormatLength Long        1  10670
0x0213 Thumbnail    YCbCrPositioning            Short       1  1
627 rmills@rmillsmbp:~ $ webpmux -get exif test.webp -o - | exiv2 -pv - | wc
Saved file - (14854 bytes)
     156    1091   10978                                                  # we still have 156 lines of metadata
628 rmills@rmillsmbp:~ $

Please don’t think that because I have been able to extract the meta data with a pipe, this project’s trivial. It’s not. I’d like us to use Exiv2’s basicio module to perform I/O within libwebp. This is because basicio supports web protocols to randomly seek data on the web (we don’t copy the whole file).

I'll take a look at the webp/webpmux libraries and make an assessment of the effort required to get basicio to perform I/O.