FACTS — 叮之前 / Before the Ding
What the voice-over says about how a chat photo travels, checked against public sources. The film names no app or company; the sources below are only where the facts come from. 小林, the cat photo and every screen on the desk are fiction.
| # | Line (voice-over) | Claim | Source | Quoted wording | Verdict |
|---|---|---|---|---|---|
| 1 | 3–4「第一步，是壓小……軟件會先把它悄悄壓縮，體積小了，看著卻差不多」 | Chat apps compress photos before sending, by default | MacRumors, WhatsApp Gets 'HD Photos' Option (18 Aug 2023): https://www.macrumors.com/2023/08/18/whatsapp-hd-photos-send-high-res-images/ | "Tapping the HD button brings up a pop-up allowing users to switch from the default Standard Quality to HD Quality." / "Previously, WhatsApp users sending photos would see the images automatically compressed…" | holds (default quality; a user can choose a higher quality, which still compresses less) |
| 2 | 5–6「來到第二站，服務器……雲端中轉站，照片先存放在這兒，等著對面來取」 | The photo is uploaded to the service's storage; the recipient's phone fetches it from there; messages can be sent while the recipient is offline | WhatsApp Encryption Overview (whitepaper, 2026-02), https://www.whatsapp.com/security/WhatsApp-Security-Whitepaper.pdf , section on attachments | "3. The sender uploads the encrypted attachment to a blob store." … "5. All receiving devices decrypt the message, retrieve the encrypted blob from the blob store" … "start sending messages to the recipient, even if the recipient is offline." | holds |
| 3 | 7–9「第三步，才輪到發通知。服務器拍了拍朋友的手機……手機才響了一聲」 | The app's server sends a message through the phone platform's push service, which delivers it to the app on the phone | Firebase Cloud Messaging overview: https://firebase.google.com/docs/cloud-messaging | "A trusted environment such as Cloud Functions for Firebase or an app server on which to build, target, and send messages." / "An Apple, Android, or web (JavaScript) client app that receives messages" "via the corresponding platform-specific transport service." | holds as a simplification: the server goes through the phone system's push channel, it does not reach the phone directly |
| 4 | 10「收到通知後，朋友的手機才真正去服務器，把照片取回來」 | The recipient's phone fetches the attachment from the server after the message (notification) arrives | WhatsApp Encryption Overview (as 2); WhatsApp Help Center, How to configure auto-download: https://faq.whatsapp.com/en/iphone/28041114 | "5. All receiving devices decrypt the message, retrieve the encrypted blob from the blob store" | holds (with auto-download on, this happens as soon as the message arrives; with it off, when the photo is tapped) |
| 5 | 11「所以網慢的時候，你會看到它先糊一下，再瞬間變清楚」 | A tiny low-resolution preview travels with the message and is shown while the full photo downloads | Telegram API, Files, stripped thumbnails: https://core.telegram.org/api/files | "A photoStrippedSize (with type i) is an extremely low-res thumbnail, embedded directly inside media location objects." "It should be shown to the user in chat message previews, or while still downloading the most appropriately sized photoSize" | holds (the preview is visible while the download is slow) |
| 6 | 13–14「如果你沒勾原圖，朋友收到的，只是那隻貓的壓縮版……原圖一直都在你的手機裡」 | By default the recipient gets the compressed copy; apps let you choose to send the original or a higher quality; the original stays on the sender's phone | as 1 (the HD / quality option) and 2 | "Tapping the HD button brings up a pop-up allowing users to switch from the default Standard Quality to HD Quality." | holds |
Illustrative numbers. The sizes on screen (原圖 4.2 MB → 壓縮後 300 KB, original 4.2 MB → compressed 300 KB) are an illustration, not a measurement of any app: a phone photo of a few megabytes and a compressed chat copy of a few hundred kilobytes are typical orders of magnitude, and the exact figures vary by phone, app and setting. The voice-over gives no number.