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what is "True random shuffle "

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MarkGaleck:
The Wikipedia article about Rockbox says it has the feature "True random shuffle".  Anybody knows whether this statement has meaning?  For example, what could "true" mean?  It is not possible to have a theoretically mathematically random shuffle in a deterministic device, is it?  Or is the "randomness" work much better than the original firmware(s)? 

Thank you

Llorean:
For example, the iRiver "shuffle" feature, when provided the same list of songs, played them in the exact same "shuffled" order each time. Rockbox has a good pseudorandom function, and generates a fresh randomly shuffled playlist every time you launch a playlist in shuffled mode, or every time a playlist repeats with the shuffle-on-repeat feature enabled.

Eriol:

--- Quote from: Llorean on August 17, 2006, 05:07:34 PM ---For example, the iRiver "shuffle" feature, when provided the same list of songs, played them in the exact same "shuffled" order each time. Rockbox has a good pseudorandom function, and generates a fresh randomly shuffled playlist every time you launch a playlist in shuffled mode, or every time a playlist repeats with the shuffle-on-repeat feature enabled.
--- End quote ---
For any player with a clock you'd think this'd be pretty trivial to do (I know my X5 has one at least), just re-seed the rand() function with the current time every time you do the re-shuffle.

For ones without a clock... re-feed the current shuffle's output into the randomness function (not exactly random, but possible if you keep a running copy of the "last random" sequence, or some representation to feed back into a generator)?  Read in some noise from a microphone/line in if either exists (very random)?  Time (clock tics) between button presses perhaps (the user input itself causes the randomness, which should be pretty random, and good for a user-centric devices like for this purpose)?

What's being done now?  I'm curious.  ;)

RotAtoR:

--- Quote from: Eriol on August 17, 2006, 05:16:02 PM ---What's being done now?  I'm curious.  ;)

--- End quote ---

It's general practice to seed it with the current (processor) clock tick, which for all devices so far is 1/100ths of seconds since rockbox was booted. A RTC is not necessary at all.

bk:
I wrote that line in the article. Llorean is correct, it refers to the fact that Rockbox shuffle is much more 'random' than iriver fw shuffle (back when I wrote it the iriver port was the only functional non-Archos port).

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