Put takes a []byte, so storing a recording meant the whole recording in
memory. A two hour meeting at 16 kHz mono is about 230 MB of WAV, and
building it from PCM held a second copy of the same size in the process
that also owns the database and the resident model. PutFile stats the
file, hashes it in a stream and renames it into place, so the peak is one
buffer regardless of length. SpoolFile hands out the scratch file it
moves from, under the media dir so it shares the same disk and the same
permissions.
Audio also gets its own per blob cap of 512 MiB. The image cap of 64 MiB
is 35 minutes of audio, which contradicted the two hour session cap: the
long meeting was exactly the one that failed to store.
audio.WAVHeader is split out of WAVFromPCM because a spooled capture
writes a placeholder header first and stamps the real length at the end.
Found in review of #73.
kami
71b42e31bd