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Radio Station Emulator
======================
First of all, since you are reading this at most probably the web/internet, let
me clarify that the "radio station" part is referring to a webradio station, a
station that resembles the classic "radio" that plays on the FM/AM and other
bands which instead of transmitting signal to the airwaves, it actually streams
data over the internet.
Secondly, the "emulator" part means that the particular radio station we are
going to talk about it has mainly pre-recorded shows to play on its program.
Live programs are also possible in this emulator by extending the core idea but
to keep it simple and trully emulator we will only consider the pre-recorded
shows, for ease and to not create a hybrid emulator, in the sense that sometimes
is an emulator, some other times is not, cause it actually plays live.
The main goal is to eliminate the streaming of data in its synchronous form and
make it asynchronous. One of the main problems moving from streaming the data
the audience is supposed to hear is that with no synchronous streaming, we would
be unable to synchronize the audience in the same way radio stations are doing
this.
At the current time this is getting written, the link to the website
https://radio.arching-kaos.com will land you to the implementated idea we are
here to talk about.
While being analytical to this point, the solution to the problem won't be of
the same degree of analysis. For this, a thesis paper is being developed but I
am eager to share the news about it and talk about how the emulator works.
Assume the pre-recorded shows and that these shows are played on after another
on a radio station. If new content is not added, the list of these shows is
repeated from the beggining.
To make the asynchronous part, we need to have each show ready to be transfered
to the audience. For convenience and for further expanding of the project, we
would be having some metadata files, describing somethings about each show and,
also, point the audience to the actual show. These metadata files, would need to
let the audience about some key elements for later use. The most important parts
are:
1. date of publishing,
2. duration,
3. pointer to the show,
4. the format of data that the show is stored in.
The third and fourth parts are for the audience to be able to play the shows.
The first and second ones, we will need them later for calculations.
Now, think that these metadata files are referenced from another file that holds
the list:
of them, with to more elements:
1. date and time of first appearance of this list and
2. total duration of the list.
To make the asynchronous, synchronous, we will need to calculate how much time
has passed since the playlist started playing for the first time. Subtracting
these two timestamps, we would get the number of seconds that have passed
since.
Timestamp(now) - Timestamp(playlist) = SecondsPassed
Dividing the SecondsPassed with the total duration of the list we would now the
times the list was fully played (the integer part of the outcome) and a ratio
of how many seconds have passed since the latest start from the beggining of the
list (the decimal part).
SecondsPassed / TotalDuration = TimesFullyPlayed + K
where TimesFullyPlayed is an integer/natural number
K = SecondsPassedSinceLastStart / TotalDuration where 0<=K<1 which also means
that SecondsPassedSinceLastStart > TotalDuration
Finding the TimesFullyPlayed + K part would be easily calculated if for the
ratio SecondsPassed/TotalDuration we would keep the integer part of the outcome
and subtract it from the actual ratio. This would leave us with K which to
convert back to seconds, we would multiply it by the TotalDuration which would
be the amount of seconds passed since the last repeatition of the list.
Knowing this amount of seconds, we would manage, knowing the durations of each
show, to calculate which show is already played, which is not and which is the
one that the audience is supposed to hear and the moment of tuning in.
This part could be achieved by looking for each show in the list, effectively
iterating until the point that the SecondsPassedSinceLastStart is greater than
the summary of the durations, that we have already iterated in our process.
When this condition is met, we get the current iterated show and load it.
Finally, we sync on that show, by subtracting the summary of the previous shows'
durations from the SecondsPassedSinceLastStart and we start playing the current
show starting at the amount of seconds we just calculated.
And we are back in synchronicity!
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