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When my playlist with 200+ songs stops shuffling through the same 20 and plays a song I haven't heard in 5 years (lemmy.world)
submitted 1 month ago by to c/memes@lemmy.world
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[–] 1 point 1 month ago (3 children)

I bet it's possible to make a function that given a song in a list it returns the next song (or previous) in such a way that it's random but for a given song the previous/next one are always the same, depending on some parameter. That way the only two things the program has to remember is the current song and the parameter used to compute the next one. Then each time shuffle is enabled a new "seed" parameter is rolled.

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  • [–] 2 points 1 month ago (2 children)

    I'm not sure how you would ensure that the songs only show up once in that list, unless you do weird shit like re-rolling the seed until you find one where this happens to be true.

    But also, that's a lot harder than just storing the shuffled list. 😅

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  • [–] 2 points 1 month ago (1 child)

    You don't have to do anything fancy, I don't think. Initialise your RNG with the seed that you have stored, shuffle the list, and then rotate the list to get to the 'first song'. Every RNG seed will give a correct result.

    If you shuffle using eg. Durstenfeld/Knuth shuffle, which is O(n), then you can make a note of the 'first song's position' and do the rotation at the end of shuffling straight to the first song, in a single pass.

    You'll still get a repeatable ordering if songs are added or removed from the playlist - the order will be different, of course - and it takes a lot less storage to write down the seed and the ID of the 'first song', which might matter if you're using a crappy old music player with very limited storage space.

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