58 rivejä
2,5 KiB
ReStructuredText
58 rivejä
2,5 KiB
ReStructuredText
EventFilters
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================
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What is an event filter? It is a mechanism to filter songs before adding them to the playlist.
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Why is it any useful? To implement something better than a priority system!
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Real world example: you have many events. Some are very long ("shows"), some are short ("jingle"). If you
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have a long show of 2hours, and a jingle every 15minutes, then at the end of your jingle you'll find 8 jingle
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stacked. That's bad! How to fix it? There are many solutions, none of them is very general or suits every
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need. EventFilter is a mechanism to have multiple filters running serially to find a reason to exclude an
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event.
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Using an event filter
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-----------------------
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larigira provides some basic filter. A simple example can be "maxwait". The principle is just "don't
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add new events if the current playing song still needs more than X seconds to finish". Setting this to, for
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example, 15 minutes, would have found only one jingle in the previous example. Great job!
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However, it wouldn't be very kind of long shows. If you have two long shows, each 2h long, scheduled let's say
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at 8:00 and 9:30. Now the second show won't start, because there is 30min remaining, and the maxwait is set
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to 15min. If you have this solution, maybe *percentwait* will better suit your needs. Set this to 200%, and
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a jingle can wait up to twice its own duration. This is like setting maxtime=4hours for the long shows, but
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maxtime=1minute for jingles. Nice!
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Examples
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----------
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Fixed wait
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~~~~~~~~~~~~~~~
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This snippet will configure larigira to wait a maximum of 5 minutes::
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LARIGIRA_EVENT_FILTERS='["maxwait"]'
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LARIGIRA_EF_MAXWAIT_SEC=300
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(60*5 = 300seconds). This will basically cancel any event that finds a currently playing audio not at its end.
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It can be recommended if you have very accurate timing or don't care about "losing" shows because the one
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preceding it lasted for too long.
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Relative wait
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~~~~~~~~~~~~~~~~
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This will configure larigira so that a 1-minute jingle can wait for a maximum of 4minutes, while a 20minutes
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event can wait up to 1h20min::
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LARIGIRA_EVENT_FILTERS='["percentwait"]'
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LARIGIRA_EF_MAXWAIT_PERC=400
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In fact, ``400`` means 400%, that is 4 times the lenght of what we're adding
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Write your own
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----------------
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You probably have some very strange usecase here. Things to decide based on your custom naming convention,
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time of the day, moon phase, whatever. So you can and should write your own eventfilter. It often boils down
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to very simple python functions and configuration of an entrypoint for the `larigira.eventfilter` entrypoint.
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