-
AAC (via .m4a and ffmpeg) is very flexible w/r/t bitrate.
-
12k AAC is still intelligble.
- This comes out to about 100KB per minute.
-
Max data size is about 3KB.
-
This could store:
- (version, UUID)
- GPS
- date/time
- sender, signature, public key hash
- recipient, public key hash
- checksum
- IP, domain, email
- (presence of image, video, audio)
-
msgpack data before qr code
- How to encode an image behind a human-readable QR code and text?
- All pixels must be black or white. Any deviation is data.
- problem: how much deviation to allow?
- Must be such that the highest value on black next to lowest on white is easily distinguished.
- E.g. assuming [0,255], say [65,190]. Thus each pixel can have 128 values (2^7).
- problem: this prevents the possibility of color.
- May or may not be an issue.
- But hamstringing ourselves early is undesirable.
- problem: how much deviation to allow?
- All pixels must be 100% luminance or 0% luminance. Any deviation is data.
- problem: how to enforce this? sounds slow.
- All pixels' 8 LSBs are data.
- allows color!
- not much math involved, just bit slicing.
- All pixels must be black or white. Any deviation is data.