Client is not able to generate dynamic thumbnail as Element can

[itsthejb]

Steps to reproduce

1. Setup mautrix/whatsapp bridge and test sending videos using the WhatsApp client itself or via the bridge
2. The message payloads are quite different in the two cases (see below and linked issue)
3. Observe thumbnails in the client vs. original Element client

Outcome

What did you expect?

In spite of lack of thumbnail payload, client generates dynamic thumbnail as Element does

What happened instead?

Element-X does not generate dynamic video thumbnails

Context: message payloads

Provided in Mautrix bridge issue:

Bridged 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 Mautrix-WhatsApp only:

{
  "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>"
}

Your phone model

iPhone 15

Operating system version

18.2

Application version

1.9.10

Homeserver

Synapse 1.120.0

Will you send logs?

No

[pixlwave]

Hey thanks for opening the issue, but given that we're running on a mobile device we're not going to commit to downloading entire videos just to extract a thumbnail from them as we have to consider the cellular connection (both from a bandwidth and data restrictions perspective). Whilst I appreciate that the bridge issue has been open for a few years, this is definitely something that should be fixed on their side.