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Show HN: ShadowCat – file transfer through QR Codes in a Browser

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1–10 of 74 posts

Re: Show HN: ShadowCat – file transfer through QR Codes in a Browser

#2
Single page file transfer using QR Codes and a browser. Sending device loads a file into the page, gets chunked. Receiver gets all the chunks through a camera, tosses lightly and reassembles, CRC to garnish. Designed to push data from an old phone that had broken comms after it took a swimming lesson in a coffee mug, it's been quite handy.

Re: Show HN: ShadowCat – file transfer through QR Codes in a Browser

#6

Single page file transfer using QR Codes and a browser. Sending device loads a file into the page, gets chunked. Receiver gets all the chunks through a camera, tosses lightly and reassembles, CRC to garnish. Designed to push data from an old phone that had broken comms after it took a swimming lesson in a coffee mug, it's been quite handy.

Interesting idea! A demo video would be great :)

Re: Show HN: ShadowCat – file transfer through QR Codes in a Browser

#7
I once heard someone create a QR code scanner to retrieve gigabytes of data, but the biggest problem is that cameras aren't powerful enough to handle it all. Essentially, the QR code needs to be downloaded to the device for loading; relying on the camera to retrieve it is very difficult. Am I wrong about this project? What's your solution?

Re: Show HN: ShadowCat – file transfer through QR Codes in a Browser

#9
post #4

I love this type of stuff. Some years ago I did something similar, but instead of QR Codes it used a convoluted mess of audio frequency modulation to send data through sound between devices. This is much more practical if you have two cameras.

> a convoluted mess of audio frequency modulation

Like a modem

Re: Show HN: ShadowCat – file transfer through QR Codes in a Browser

#10
Cool! Out of curiosity, since qr-codes can contain binary data -- rather than base64, have you tried inserting the file as-is? That way you could do away with the ASCII separator and have a binary header as well. This would spend less frames for the same amount of data, but I'm not sure if it would be computationally cheaper. The other alternative would be the alphanumeric mode of qr-codes, but then you lose lowercase.
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