ExifTool Forum

ExifTool => The "exiftool" Application => Topic started by: ejball on May 07, 2014, 01:59:08 PM

Title: Animated WebP
Post by: ejball on May 07, 2014, 01:59:08 PM
It isn't a high priority for us at this point, but one file format that exiftool doesn't appear to support (as of 9.59) is Animated WebP.

Sample image: http://downloads.webmproject.org/webp/images/dancing_banana2.lossless.webp
Source: https://developers.google.com/speed/webp/faq (near the bottom)
Title: Re: Animated WebP
Post by: Phil Harvey on May 07, 2014, 02:15:38 PM
Why do you say it isn't supported?  ExifTool reads this file and sould extract any metadata if some existed.

- Phil

Edit:  Ah, I guess I could be decoding the VP8X chunk to get the ImageWidth/ImageHeight.  But there isn't much else that would be useful to decode from this file.
Title: Re: Animated WebP
Post by: ejball on May 07, 2014, 02:33:50 PM
Yes, the image size would be great, akin to what exiftool extracts from non-animated WebP files, e.g. those found here: https://developers.google.com/speed/webp/gallery2

Animation metadata (especially duration) would also be useful to us, akin to what exiftool extracts from animated GIFs and WebM files.

Title: Re: Animated WebP
Post by: Phil Harvey on May 07, 2014, 02:39:48 PM
Looking at the spec, I would have to add up the durations of each individual frame to calculate the Duration.  Too much work.

But I should add support for their version of XMP.  Apparently they use a different chunk name than other RIFF formats (stupid), although I haven't seen a sample containing XMP yet.

- Phil

Edit:  I looked at the GIF code, and it sums the durations of each frame, so I should really do this for WebP too.  I figured out a way to do this without having to patch the parsing code like I did for GIF, so it won't be too much work after all.
Title: Re: Animated WebP
Post by: ejball on May 08, 2014, 08:58:52 PM
That's great, thanks!