Videos sent via WhatsApp bot don't show thumbnails.

[imding]

Hi, I set up Synapse v1.64.0 and mautrix/whatsapp v0.6.0 with Kubernetes and after inspecting the logs, I noticed that the thumbnail_info field isn't sent by the WhatsApp bot with the m.video event (link), which results in videos having blank thumbnails in the Element app.

Video attachments that do not go through the bot show thumbnails just fine.

[kinduff]

Would love to contribute but I don't know where to start, can you point me to the right direction?

[itsthejb]

This is such a noticeable bug. No attempt to fix it in years?

Here's some extra context from me: Two videos sent, one with the bridge through Element-X iOS:

{
  "type": "m.room.message",
  "sender": "@<>:<redacted>",
  "content": {
    "msgtype": "m.video",
    "body": "<redacted> ",
    "format": "org.matrix.custom.html",
    "formatted_body": "<redacted>",
    "filename": "94B6E60C-45D6-4114-A1D5-342841CE349B.mp4",
    "url": "mxc://<redacted>/REsrKiRAiCuRbrfTLkSUFIrS",
    "info": {
      "duration": 26370,
      "h": 720,
      "w": 1280,
      "mimetype": "video/mp4",
      "size": 34728286,
      "thumbnail_info": {
        "h": 450,
        "w": 800,
        "mimetype": "image/jpeg",
        "size": 135285
      },
      "thumbnail_url": "mxc://<redacted>/EFOWLRrwsLtYTYIHTmYBpGnq",
      "xyz.amorgan.blurhash": "KQGu?lIoM|?KWBM{.7R%t6"
    }
  },
  "origin_server_ts": 1736240406650,
  "unsigned": {
    "membership": "join",
    "age": 2877522
  },
  "event_id": "$3A9vmWM6AxnqSL9HYqDycpmPpBbrQ1f1wKbZ-iyLLA4",
  "room_id": "!vvAqySpsGiHYNgxulG:<redacted>"
}

And the second sent directly using Whatsapp iOS and then bridged via this:

{
  "type": "m.room.message",
  "sender": "@jc:<redacted>",
  "content": {
    "msgtype": "m.video",
    "body": "<redacted>",
    "filename": "video.mp4",
    "url": "mxc://<redacted>/OHpDpeKcjGQjhXWBuyatsoms",
    "info": {
      "duration": 49000,
      "h": 848,
      "w": 480,
      "mimetype": "video/mp4",
      "size": 8952788
    }
  },
  "origin_server_ts": 1736240524742,
  "unsigned": {
    "membership": "join",
    "age": 2759430
  },
  "event_id": "$08ni8pKv70YvOU4FuFF9BA1gGQKKn1FsnxUIYKpVx9c",
  "room_id": "!vvAqySpsGiHYNgxulG:<redacted>"
}

Considerably less info with the bridged version.

Note: The same applies to all messages sent over WhatsApp from others, meaning no thumbnail data for received video messages.

I notice that the original Element client handles this better than Element-X right now. I believe it generates its own thumbnail. However, I think the underlying issue is with the bridge here