Animated QR Transfer Speed and Camera Troubleshooting

Throughput depends on successful decoding

Useful data throughput is roughly the payload per frame multiplied by the number of different frames successfully decoded per second, minus protocol, parity, and repetition overhead. The selected playback rate does not mean the camera successfully decodes that many frames per second. Capturing the same frame repeatedly adds no new data. Files and text use the same transfer flow. Animation frame rate alone cannot justify a 100 KB/s claim, and bits per second are not bytes per second.

Reception does not advance

Confirm that the receiver is using the camera inside this tool, rather than remaining in the system camera app. The system camera opens the entry link; it does not assemble the file or text. Check camera permission and HTTPS. If an in-app browser restricts permission or downloads, open the receiver address in the system browser. Close another app if it is occupying the camera.

Improve scan reliability

1. Clean the lens and raise screen brightness while avoiding glare.
2. Hold the camera approximately parallel to the screen. Keep the whole code and its white border visible.
3. Adjust the distance and wait for autofocus. From too far away the modules become tiny; too close may be outside the camera's focus range.
4. Switch from fast to stable mode or reduce playback speed. Fewer, clearer codes can deliver more useful data than a faster animation with frequent failures.
5. Keep both pages visible and delay automatic screen locking. Power saving, overheating, and background tabs can slow decoding.

Stable and fast modes

Stable displays one QR code at a time and is the recommended starting point for phones, small screens, and ordinary cameras. Fast displays four codes and suits a larger sending display. It can improve useful throughput only when the camera can clearly read all four codes. Both start at 12 frames per second; reduce the playback rate if needed. The sender limits its rate based on local rendering time, not receiver feedback. It cannot automatically know the receiver's decoding speed or whether reception is complete.

Why the final stage can take longer

Some frames may be duplicates or fail verification because of blur. Missing chunks still need to arrive through later passes or parity frames. Continue scanning the same transfer instead of repeatedly restarting. If final integrity verification fails, initiate a new transfer with more conservative settings rather than treating an unverified result as complete.

Sending stops after editing text

Editing stops the old transfer so the receiver cannot keep receiving an outdated message. Finish editing, generate new QR codes, and start sending again. If the receiver is still collecting the previous version, restart reception before scanning the new transfer.

Copying and downloading text

Received text preserves line breaks and spaces and is displayed as plain text. Copying requires clipboard permission in the browser. If blocked, select the text manually or download a UTF-8 TXT file. Links do not open automatically, and HTML is not rendered as a page.

Limits and data handling

Files are capped at 5 MiB. Text has the same limit measured in UTF-8 bytes; Chinese characters and emoji can use multiple bytes each. This is a size limit, not a promise that transfer will finish within a particular time. An unprepared first visit cannot load the receiver without a connection. Even after preparation, check that the cache is retained and camera access works. File and text encoding, camera processing, and reconstruction run in the current browser. Transfer contents are not uploaded to FreeTool. The initial load needs a connection. Complete offline preparation on the receiving device while online to use its dedicated receiver offline; prepare again if the browser clears its cache. QR codes are not encryption: anyone who can film the screen may receive the content. Visible QR codes may be filmed by bystanders. CRC32 and SHA-256 provide no confidentiality. Use a trusted setting for the contents you show.

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