Description
During development of the android interface I realised that a chat-like interface may be more user friendly than an email-like interface. I propose a protocol change for chat-like objects. They would use a new message type, and a bit in the pubkey bitfield would indicate whether the address should be used for chat message types instead of email-like message type.
The chat message type would contain a reference to previous objects (so that ordering can be done by the client), and could contain UTF-8 text, images or audio (maybe with separate message types for each, or all in one). Video wouldn't fit within maximum object size, so can probably be skipped. For audio, I tested the Opus codec, which produces about 7kbit/s file at the minimum size and still is understandable. Opus codec is widely supported by open source implementation and a python package.
For compatibility outside of kivy, the QT interface would contain another tab for a chat interface. The API would have to be updated too.
For storing, a new table is proposed.
I also propose to extend the messagetype class to allow not only encoding / decoding, but also saving/loading/searching/etc. For old message types it can be refactored later.
This proposal can be implemented independently of my recent proposal for getting rid of pubkey objects #1612 .