When playing back buffered async frames, this reduces the probability
that new frames will be missed/skipped due to jitter in the system
timestamps.
If a buffered async source is playing at the same framerate as the
compositor and there is no jitter in the async source's timestamps, then
the async source will play back perfectly in sync with the compositor
thanks to this change, ensuring that there's no skipped or missed frames
in video playback.
The "clamped" video time is the system time per video frame that is
closest to the current system time, but always divisible by the frame
interval. For example, if the last frame system timestamp was 1600 and
the new frame is 2500, but the frame interval is 800, then the
"clamped" video time is 2400.
This clamped value is useful to get the relative system time without any
jitter.
When buffering is enabled for an async video source, sometimes minor
drift in timestamps or unexpected delays to frames can cause frames to
slowly buffer more and more in memory, in some cases eventually causing
the system to run out of memory.
The circumstances in which this can happen seems to depend on both the
computer and the devices in use. So far, the only known circumstances
in which this happens are with heavily buffered devices, such as
hauppauge, where decoding can sometimes take too long and cause
continual frame playback delay, and thus continual buffering until
memory runs out. I've never been able to replicate it on any of my
machines however, even after hours of testing.
This patch is a precautionary measure that puts a hard limit on the
number of async frames that can be currently queued to prevent any case
where memory might continually build for whatever reason. If it goes
over the limit, it clears the cache to reset the buffering.
I had a user with this problem test this patch with success and positive
feedback, and the intervals between buffering resets were long to where
it wasn't even noticeable while streaming/recording.
Ideally when decoding frames (such as from those devices), frame
dropping should be used to ensure playback doesn't incur extra delay,
although this sort of hard limit on the frame cache should still be
implemented regardless just as a safety precaution. For DirectShow
encoded devices I should just switch to faruton's libff for decoding and
enable the frame dropping options. It would probably explain why no
one's ever reported it for the media source, and pretty much only from
DirectShow device usage.
Found via UBSan, actual errors (addresses not pruned for illustrative purposes):
"runtime error: store to misaligned address 0x7f9a9178e84c for type
'size_t' (aka 'unsigned long'), which requires 8 byte alignment"
"runtime error: load of misaligned address 0x7f9a9140f2cf for type
'size_t' (aka 'unsigned long'), which requires 8 byte alignment"
The screen index returned from XDefaultScreen is 0-based, and we were
decrementing it before the check to see if it had reached 0 rather than
after, so in the default_screen function it would always end up getting
either the wrong screen or no screen.
When xcb_query_pointer and xcb_query_pointer_reply was called with no
valid screen, it would fail with an error, thus making it so that the
mouse buttons could not be properly captured as hotkeys.
Implements exponential backoff for consecutive reconnects, which is
useful to prevent too many connections from trying to reconnect back to
a service at once over a short period of time in the case of potential
service downtime. Exponential backoff causes each subsequent reconnect
attempt to double its timeout duration.
This optionally allows the front-end to know what the current timeout
value in seconds is set to for the reconnection without having to call
an extra API function to find that out.
Implement the log_processor_info function on bsd and add ifdefs to only
build the implementation specific to the platform.
Also add an ifdef around the call to that function to make sure it will
only be called on platforms where it is actually implemented.
Split the function logging the processor information on nix into two
parts. The part logging the number of logical cores is portable and
works on all systems that support POSIX.1 while the other part is
specific to linux.
Add the relevant header file needed on FreeBSD and utilize yet another
ifdef to call pthread_set_name_np as the function name differs from
those on the other platforms.
Add definition on FreeBSD to enable getline in stdio, as it is not
(yet ?) available by default. According to the manpage getline was a
GNU extension but was standardized in POSIX.1-2008.
