The advantages of the new schema are:
* overlapping recordings can be unambiguously described and viewed.
This is a significant problem right now; the clock on my cameras appears to
run faster than the (NTP-synchronized) clock on my NVR. Thus, if an
RTSP session drops and is quickly reconnected, there's likely to be
overlap.
* less I/O is required to view mp4s when there are multiple cameras.
This is a pretty dramatic difference in the number of database read
syscalls with pragma page_size = 1024 (605 -> 39 in one test),
although I'm not sure how much of that maps to actual I/O wait time.
That's probably as dramatic as it is due to overflow page chaining.
But even with larger page sizes, there's an improvement. It helps to
stop interleaving the video_index fields from different cameras.
There are changes to the JSON API to take advantage of this, described
in design/api.md.
There's an upgrade procedure, described in guide/schema.md.
Now it's possible to quickly determine what calendar days have data and then
query recordings for just the day(s) of interest with their returned
{start,end}_time_usec.
I tested these in VLC and QuickTime. Both players appear to ignore the
as the track dimensions, track transformation matrix, box dimensions, and box
justification. I just left them at default values then.
Automated testing is minimal. There's a new test that the resulting .mp4
parses, but I didn't actually ensure correctness of the subtitles in any way.
Scott Lamb