There could have been a write error or allocation error while building
the json file that we can detect in spa_json_builder_close().
Error out instead of silently using a truncated JSON.
Use spa_autofree for the memory to make cleanup easier.
Make a function like alloca but with overflow checks and a max
allocation size.
Use this function where we can and also make sure that all alloca calls
are in some way limited.
The sender makes an input stream for each connected client. This makes
it easier to do the per client conversion using the adapter and send
different channels to clients.
The receiver uses linear regression to map ringbuffer indexes to server
timestamps and server timestamps to client timestamps. It can then
schedule playback against its own clock.
