Avif video is autoplayed even if autoplay gif & video is off in settings

[vranki]

Steps to reproduce

1. Check that in preferences automatically playing gifs and videos are disabled.
2. Someone sends an avif format file that is a video in a room

Outcome

What did you expect?

A still with play button to play the video on consent

What happened instead?

Video is automatically played in the preview. I think it is interpreted as a image file, even if it contains a video.

Operating system

No response

Browser information

Firefox 143.1

URL for webapp

chat.hacklab.fi

Application version

Hacklab.fi Element version: 1.12.0 Crypto version: Rust SDK 0.14.0 (c3b7918), Vodozemac 0.9.0

Homeserver

hacklab.fi

Will you send logs?

No

[vranki]

I'd attach an example file but github doesn't accept avif files as attachments. Let me know if you need one to reproduce the issue.

[t3chguy]

Can you share the View Source for the event in question? My browser won't even give me a mimetype for avifs files so sending would send as a file, not a video nor image. My guess is someone sent the avifs file with msgtype m.image rather than m.video

[t3chguy]

Yeah as expected, trying to send an AVIFS file in Chrome yields no mimetype so Element has no clue that the file is an image or video so just sends it as a file

Firefox on macOS also can't mimetype it.

You can use https://jsfiddle.net/2c7o9nak/ to try querying the mime type your browser sees, it isn't always the same between OSes but you didn't specify yours.

[vranki]

I tested on Firefox on Windows, sorry for not specifying. Sounds like plausible explanation. Not sure what is the correct fix - should browsers get support for it eventually or is this something Element should act on?

[t3chguy]

We rely on the browser to identify file types, just like we rely on the browser to render them. Normally a browser will identify things correctly if they can be rendered.

Still waiting for info from you

Can you share the View Source for the event in question?

[vranki]

Event source:

{
  "content": {
    "body": "siili.avif",
    "info": {
      "h": 420,
      "mimetype": "image/avif",
      "org.matrix.msc4230.is_animated": false,
      "size": 582657,
      "thumbnail_info": {
        "h": 420,
        "mimetype": "image/png",
        "size": 386367,
        "w": 420
      },
      "thumbnail_url": "mxc://kapsi.fi/4c5e7e91e07fc21409070753fa5a5ae4cb10f67b1971544792131174400",
      "w": 420,
      "xyz.amorgan.blurhash": "UBE_Kx+v4U}?^kWqVsS202S~~VRj9Hay-:ay"
    },
    "m.mentions": {},
    "msgtype": "m.image",
    "url": "mxc://kapsi.fi/85248091c577ace780539cc258fccdeb57b0d70c1971544792689016832"
  },
  "origin_server_ts": 1758887882909,
  "room_id": "!mxfi-nN4ts_AFaA1Uf7L9oBdjXOr4dQPtGmg8B6eLGk",
  "sender": "@jassu:kapsi.fi",
  "type": "m.room.message",
  "unsigned": {
    "membership": "join"
  },
  "event_id": "$8j7jzSWpilVAZYOGi0QcQYol3vqAiy4Gu3wk-mYZUTY",
  "user_id": "@jassu:kapsi.fi"
}

[t3chguy]

So yes it was sent as an image rather than a video, which is arguably correct if it is closer to a gif than av1. Might just be a case of adding the image/avif mimetype to the "possibly animated" list to fix, not that it would fix sending such images from Web Browsers which fail to identify the mimetype, but rendering events like the one you have shared would work fine.

[t3chguy]

So the issue here is on the sender side

"org.matrix.msc4230.is_animated": false,

They are stating that it is not in fact animated.

If I change that to true then I get the 2nd in the above (great gif/whatever btw)

Was that sent from Element Web/Desktop or another client?